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Nature's clean-up crew: Quantifying ecosystem services offered by a migratory avian scavenger on a continental scale
Abstract
Despite its importance for ecosystem and human health, the cleaning service provided by scavenging birds is frequently disregarded. We evaluated this ecosystem service provided by a migratory species at a continental scale, estimating the amount of annual organic material removal, and the cost of artificially replacing the service. Road surveys conducted between 2005 and 2011, indicated an abundance of Turkey Vultures (Cathartes aura) of nearly 9,000 birds along 27,658 km (22,127 km2), suggesting that the total global population could approximate 13 million birds. The calculated individual food intake (252 g/day) suggests that the surveyed population remove 1,000 tons of organic material per year –a monetized service of more than 500,000 USD, that could reach 700 million USD per year for the global population. Movement data from 22 tagged birds showed that the ecosystem service is maximized at the breeding and wintering areas, where Turkey Vultures spend most of the year (74–92% of time). The huge amount of organic material removed by Turkey Vultures at a continental scale, and the economic relevance of their service, highlight the importance of widespread and abundant populations of scavenging birds and their significant role in protecting the health of the environment and human wellbeing.
... This reduces not only sources of dangerous pathogens, which could be of importance for disease regulation , but also gases produced by rotting organic material. Moreover, this ecosystem service has the financial benefit of reducing the cost of using alternative disposal methods to remove carcasses (Grilli et al., 2019;Morales-Reyes et al., 2015). Vultures arrive and feed quickly on animals that have recently died, the consumption of a medium-sized carcass possibly taking only few minutes when many birds are present Carrete et al., 2010;Houston, 1986;Ogada et al., 2012b). ...
... For this, we considered that vultures feed as much as they can to cover their daily caloric requirements. We computed the daily food intake (FI) of each vulture species following the methodology of Grilli et al. (2019). Briefly, we estimated daily food intake as: ...
... Ranges of population estimates for each vulture species were obtained from Birds of the World Database and from IUCN Red List (IUCN, 2021; Table 2). In the case of the turkey vulture (Cathartes aura) we used the global population estimates from Grilli et al. (2019). The population abundances used should be taken with caution since several are rough estimates, and populations may have changed. ...
Dead animals release greenhouse gases to the atmosphere through natural decomposition or because they have to be processed by disposal methods such as composting or rendering. Obligate scavenging birds (vultures) consume dead animals and are among the most efficient terrestrial scavengers. They may therefore contribute to a considerable reduction in sources of greenhouse gases. Here, we quantify the global contribution of vultures in reducing greenhouse gas emissions by consuming organic material. First, we evaluated a scenario where all the dead animals that can be consumed by vultures every year have to be disposed of by composting, anaerobic decomposition (e.g., burial), anaerobic digestion or rendering. Second, we assessed a scenario in which dead animals are left to decompose in the environment. Current vulture populations (~134-140 million individuals) may reduce emissions of 3.03-60.70 Tg CO 2 eq. per year, depending on the disposal method implemented, without considering carcass transport to disposal plants. Alternatively, they may reduce emissions of 13.02 Tg CO 2 per year if dead animals remain in the environment. Over recent years a decline in vulture populations worldwide has led to a decrease of a 30 % in their capacity to mitigate greenhouse gases emissions. A few abundant vulture species reduce almost 98 % of the maximum emissions potentially removed worldwide by all extant vulture species over one year. This ecosystem service contributed by vultures to humans and nature cannot easily be replaced by other species, including humans. Moreover, supplanting this contribution with alternative carcass disposal methods is expensive and harmful to the environment due to emissions generated in the process. Our results highlight an important service that vultures provide worldwide, which is relevant in the current context of global warming.
... South American cool-temperate migration; Joseph 1997), following one of the shortest routes known for any Turkey Vulture population in America. Of the individuals tagged in northwestern Argentine Patagonia, one migrated short distance towards Uruguay, also using the South American cool-temperate migration system (see Graña Grilli et al. 2017Grilli et al. , 2019. Conversely, the remaining tagged individuals migrated northward as far as Bolivia, Brazil, and even Colombia (see Graña Grilli et al. 2017Grilli et al. , 2019, crossing the tropic of Capricorn (i.e. ...
... Of the individuals tagged in northwestern Argentine Patagonia, one migrated short distance towards Uruguay, also using the South American cool-temperate migration system (see Graña Grilli et al. 2017Grilli et al. , 2019. Conversely, the remaining tagged individuals migrated northward as far as Bolivia, Brazil, and even Colombia (see Graña Grilli et al. 2017Grilli et al. , 2019, crossing the tropic of Capricorn (i.e. South American temperate-tropical migration ;Joseph 1997). ...
Bird migration in the Neotropics is complex and highly diverse. Indeed, for many taxa, basic questions such as where they go are still relevant. Satellite-tracking studies of Turkey Vulture (Cathartes aura) migration have revealed extensive variability in their movement strategies, contributing to their widespread distribution. However, South American migratory populations are still among the least explored. By integrating five years of satellite-tracking data, citizen science databases and classical raptor monitoring techniques, we present a case study reporting a hitherto unknown nonbreeding area for the Turkey Vulture subspecies ruficollis. Specifically, we document that a minor proportion of the population that breeds in northwestern Argentine Patagonia migrates northwards to central Chile at the beginning of the austral autumn. Our findings improve our basic knowledge of the Turkey Vulture migration within the Neotropics and establish a baseline to study the movement strategies of the migratory ruficollis populations breeding in high latitudes of South America.
... Obligate scavenger birds have large home ranges (Alarcón and Lambertucci, 2018), so may spread the virus to distant terrestrial areas. For example, Andean condors can travel up to 350 km per day (Lambertucci et al., 2014) and turkey vultures are migratory birds that can travel thousands of kilometers during their migration in the Americas (Grilli et al., 2019). In Peru, condors move regularly between the coastline and the Andean region (Gamarra-Toledo et al., 2023b), which could favor the spread of HPIV to terrestrial environments in the mountains. ...
... Wild birds affected in Peru and the surrounding countries are (Patrial et al., 2011;Vinueza-Hidalgo et al., 2015). Finally, turkey vultures can move between several South American countries such as Argentina, Chile, Bolivia, Peru, Uruguay and Brazil (Billerman et al., 2022;Grilli et al., 2019;Kirk and Mossman, 2020). Future work should therefore focus on mitigation action and early detections in affected sites and sites potentially affected in the future, based on the birds' movements. ...
The recent panzootic of Highly Pathogenic Avian Influenza (HPAI) A (H5N1) has affected hundreds of thousands of wild birds around the world. Here, we analyze the outcomes of the first H5N1 outbreak in wild birds of Peruvian protected areas. The first detection of H5N1 was confirmed in dead Peruvian pelicans (Pelecanus thagus) on 13 November 2022; the outbreak then rapidly spread to diverse areas along the Peruvian coast. By mid-March 2023, the species affected and number of dead individuals found was alarming: we found at least 100,485 wild birds belonging to 24 species (some of them threatened), which died due to this virus. The number of bird species and individuals affected by this disease in Peru is of conservation concern due to the severe effect of this virus on these populations and the ecosystem services they provide. This emerging pathogen killed, for instance, around 20 % of the pelican population inhabiting marine protected areas in Peru. We call on authorities and conservation managers in South America to be alert and implement actions such as rapid removal of infected carcasses and epidemiological surveillance to limit the spread of this virus and its consequent impact on wildlife. We must prevent this pathogen spreading to other regions in South America and Antarctica, where many potentially susceptible species live and need to be preserved. Since this emerging pathogen has produced high bird mortality worldwide, it should be addressed as a new threat to the survival of several bird species around the world.
... Vultures and other terrestrial scavengers are often described as important components of ecosystems, and as ES providers (O'Bryan et al. 2018). Vultures (family: Accipitridae and Cathartidae) are able to consume, and thus recycle, substantial amounts of organic waste (Grilli et al. 2019). This ecosystem function, when put in action, translates into ecosystem services, such as decomposing waste, which represent nature's actual contribution to people (Gangoso et al., 2013). ...
... Vultures are capable of consuming large quantities of organic material (Mateo-Tomás et al., 2017). Such disposal service was recently quantified for the total population of one vulture species, the Turkey vulture Cathartes aura, and could reach up to 700 million USD per year in economic value to humans (Grilli et al. 2019) in the Americas. Carcass consumption by vultures also reduces the release of green-house gas emissions through avoided carcass transportation and incineration (Morales-Reyes et al. 2015). ...
Nature’s contribution to people (i.e. ecosystem services) is becoming integral to conservation science and policy, yet our knowledge is restricted to only a few services and taxa. Vultures (family: Accipitridae and Cathartidae), most of which are threatened with extinction, have been touted for delivering regulation and maintenance services via their capacity to rapidly consume organic matter. As such, their appellation as “nature’s clean-up crew” has become very popular. However, a comprehensive evaluation of the supporting evidence for such appellation was absent from the published literature. We performed a systematic review and evidence assessment to quantify the global contribution of vultures towards over 20 ecosystem services and disservices. Our analysis determined a critical imbalance in the scope and focus of published research. In contrast to the birds’ popularised image as cleaners of the environment, we found only weak evidence to support any regulation and maintenance services for vultures. Moreover, studies on regulation and maintenance disservices were prominent. The only ecosystem services supported by strong evidence were cultural, although even these were evidenced by a limited number of studies. Finally, we unveil major knowledge gaps in the ecosystem service and disservice literature on a taxonomic and spatial scale related to vultures. Our analysis highlights the urgent need to quantify the net contribution of vultures to people.
... Vultures are the only obligate scavengers among all terrestrial vertebrates, and have potential to deliver critical ecosystem services, such as organic waste decomposition and sanitation, climate change mitigation and ecotourism, among others (Buechley and Ş ekercioglu, 2016;Grilli et al., 2019). Therefore, conserving vultures has wide-reaching implications for ecosystem health and human wellbeing (Buechley and Ş ekercioglu, 2016;Santangeli et al., 2019). ...
... While such a crisis could be imminent in this region, we do not have the knowledge base to detect it in a timely manner, not to mention address it before it is too late. As obligate scavengers, vultures provide critical nature's contributions to people, benefitting human societies throughout the Americas with their waste disposal services (Grilli et al., 2019). Failure to conserve them will represent a severe cost to societies, both financially and culturally (Buechley and Ş ekercioglu, 2016). ...
Proactive approaches are typically more cost-effective than reactive ones, and this is clearly the case for biodiversity conservation. Research and conservation actions for Old World vultures typically followed large population declines, particularly in Asia and Africa. These are clear examples of reactive intensive conservation management. We here contend that there are signs of a potential upcoming continental vulture crisis in the New World. New Word vultures share many of the threats that have decimated their Old World counterparts, such as toxicosis from poisoning and lead. At the same time, we show that quantitative data on key demographic and conservation action aspects are largely lacking for many New World vultures, particularly those restricted to the Neotropics. This knowledge gap prevents us from quantifying population declines, and in turn, to design effective management actions to mitigate and prevent further declines. Essentially, if the current knowledge gaps are not filled rapidly, we will miss the opportunity to apply proactive conservation. We here propose a set of actions to prevent a potential vulture crisis in the Americas.
... The advantages related to these sanitation services, both economic and environmental, have not been quantified in Africa, although they may be deduced from studies conducted elsewhere. The global population of Turkey Vultures (estimated at about 13 million birds) render clean-up services valued at $700 million per year across this species' range in North and South America (Grilli et al. 2019). In developed countries such as Spain, the industrial destruction of carcasses averages approximately $85-123 per metric ton but vultures may remove 9.9 million tons of carcasses per year, saving farmers approximately $26 per animal (Margalida and Colomer 2012). ...
... The extent of global travel and the ability of many EIDs to disperse rapidly (as is evident from the recent coronavirus disease of 2019 pandemic), highlight the need for robust early identification systems (Miller et al. 2013), and the global importance of protecting disease-regulating species, especially in countries where early identification systems are lacking. Indeed, the massive and perpetually increasing production of organic waste, driven by unchecked human population growth, will only increase the functional significance of vultures in the developing world (Grilli et al. 2019). ...
Vultures are a key component of an effective scavenger guild and have evolved a number of adaptations that allow them to locate and dispose of carcasses quickly and efficiently. The continuing decline of African vultures is threatening the stability of the African scavenger guild, which may result in increased carcass decomposition times and thus, more rapid development of pathogenic bacteria. The absence of competitive regulation by these apex scavengers may also result in changes in the composition of the vertebrate scavenger guild, with an increase in mammalian scavengers giving rise to increased contact rates at carcasses, which may increase the risk of viral disease transmission to humans, livestock, and other wildlife. Although the economic value of vultures in terms of the sanitation services they provide has been evaluated, their contribution to the economics of human health and veterinary care remains to be quantified. Efforts to do so are hampered by lack of data, as well as a number of confounding factors that may mask causality, such as improved disease prevention and surveillance systems. However, the circumstantial nature of the link between vultures and disease prevention should not deter efforts to conserve them, as their regulation of mammalian scavengers and the sanitation services they provide place them firmly within the sphere of One Health, thereby warranting their urgent protection. The restoration of vulture populations and the ecosystem services they provide will benefit the welfare of all humans, but particularly those who are most vulnerable to economic instability and the spillover of disease at the human-wildlife-livestock interface.
... In the northern hemisphere (mainly the USA and Europe), facultative terrestrial scavengers decrease their home range as the level of human impact increases (Main et al., 2020), potentially affecting the carrion consumption services (Table 1). On the contrary, flying scavengers such as vultures continue long-distance movements despite increased terrestrial fragmentation (Dodge et al., 2014;Grilli et al., 2019). In this way, they maintain WEF such as disease spread control and carrion removal (Table 1). ...
... Vultures maintain long-distance movement and consumption of carrion despite terrestrial fragmentation (Dodge et al., 2014;Grilli et al., 2019;Gutiérrez-Cánovas et al., 2020). Deceleration of nutrient cycling (Hill et al., 2018;Morales-Reyes et al., 2017) and rise in disease transmission (Markandya et al., 2008;Plaza et al., 2020). ...
Land use change alters wildlife critical animal behaviours such as movement, becoming the main driver threatening wildlife ecological functions (WEF) and nature’s contribution to people (NCP) provided by terrestrial species. Despite the negative impacts of current rates of terrestrial fragmentation on WEF, many ecological processes can be still occurring through aerial habitats. Here, we propose and discuss that the movement capabilities of aerial species, as well their functional redundancy with non-flying wildlife, are the mechanisms by which some ecological processes can be still occurring. We show examples of how the movements of aerial wildlife may be masking the loss of important functions and contributions by compensating for the lost ecosystem functions previously provided by terrestrial wildlife. We also highlight the implications of losing aerial wildlife in areas where that functional redundancy was already lost due to the impacts of land use change on terrestrial wildlife. We suggest to consider flying wildlife as a biological insurance against the loss of WEF and NCP due to terrestrial fragmentation and proposed some aeroconservation measures.
... Consequently, their distribution of carcass biomass via scat deposition fertilizes soil across much larger distances than any other non-avian scavenger (Ganz et al. 2012;Beasley et al. 2019). The global economic benefit of carcass removal and potential disease mitigation by vultures remains unquantified as we lack a full understanding of the services they provide (Carucci et al. 2022; but see Grilli et al. 2019). ...
Carcass consumption by scavengers plays a critical role in wildlife and human health by providing services that maintain ecosystem functioning and potentially mitigate disease spreading. Vultures are particularly efficient scavengers, but their populations have sharply declined in Europe, Asia and Africa, raising concerns about similar declines in the comparatively less studied species of the Americas. While the effects of vulture absence on other vertebrate scavengers have been examined, the impact on invertebrate scavengers and their role in carrion decomposition remains unexplored. To determine the effects of vulture decline, specifically neotropical cathartid vultures, we experimentally excluded this functional group from domestic pig carcasses (Sus scrofa) in Costa Rica, under different habitat conditions (grassland and forest) and across seasons with the aim to assess the impact of vulture exclusion on carrion decomposition and insect abundance. Vulture exclusion halved carcass decomposition rates relative to control carcasses without exclusion. Accordingly, vulture abundance at control carcasses was positively correlated with carcass decomposition rate. Vulture exclusion doubled fly abundance at carcasses relative to controls but did not significantly impact dung beetle abundance at carcasses. These findings suggest that neotropical vultures are instrumental in rapid carrion decomposition, a service that invertebrates alone cannot fully compensate for, underscoring the potential ecological and public health risks associated with neotropical vulture declines and increased flies at carrion sites. Further research is needed to understand the broader implications of vulture loss on ecosystem services and zoonotic disease transmission in the Neotropics.
... Vultures are the clean-up crew of the ecosystem (Grilli et al. 2019), preventing the accumulation of decaying matter (Gutiérrez-Cánovas et al. 2020). Their highly acidic stomachs make them uniquely effective at halting the spread of diseases (Van Den Heever et al. 2021). ...
Vultures are highly effective scavengers but face numerous threats that increase their extinction risk. Globally, vulture populations are declining due to various anthropogenic factors that impact their abundance and distribution. Despite large declines, most populations of vultures remain unassessed, especially in Africa. We assessed the abundance and spatial distribution of the critically endangered Hooded Vulture (Necrosyrtes monachus) across urban and rural areas of the Cape Coast metropolis in southern Ghana. We conducted Hooded Vulture counts at verified permanent roosts and feeding sites simultaneously during the wet and dry seasons. We found an average of 50 ± 10 (SD) and 50 ± 13 vultures in the dry and wet seasons, respectively, at the selected study areas. Vulture counts did not vary with season, but did differ by age. Adults outnumbered immature birds in the study area by a ratio of 3:1, suggesting possible population viability issues in the future. We investigated spatial distribution using past and present vulture occurrences from the Global Biodiversity Information Facility dataset and observations from this study. Using maximum entropy modeling, we investigated the influence of eight environmental variables on spatial distribution. Distance to food sources and roads—key proxies and indicators of human activity—were the most important factors influencing vulture distribution. We also found five permanent roosts and eight feeding sites in the study area. This study provided valuable baseline data for future conservation and monitoring. We recommend additional research and focused conservation initiatives, particularly targeting stakeholders around sites of the local vulture populations.
... The Andean Condor Vultur gryphus is an obligate avian scavenger distributed along the Andes from Venezuela to Argentina (Ferguson-Lees and Christie 2001). Like other vulture species, it plays a critical role in maintaining ecological balance, public health, and sustainable development (Grilli et al. 2019;Ogada et al. 2012;Santangeli et al. 2024). Furthermore, it is a species of great cultural significance and is considered a unique symbol of the Andes (Ibarra et al. 2012;Santangeli et al. 2024). ...
Andean Condor Vultur gryphus populations are particularly low in the northern Andes. The species is considered nearly eradicated from Venezuela and listed as “Endangered” in Ecuador and “Critically Endangered” in Colombia. Even though it is severely endangered, the size of the Colombian condor population remains unknown. Using a citizen science-based approach, we conducted the first Andean Condor count for Colombia with the help of 207 observers at 84 simultaneous observation points. We used N-mixture models for spatially replicated counts to estimate the condor population. The total number of condors recorded simultaneously was 63 individuals, and we estimated a population size of 175–269 individuals using a maximum likelihood approach and 165–222 and 172–229 for the two best models using the Bayesian approach. Adults were observed more frequently than juveniles (1:0.43), a common pattern among raptors related to the higher mortality rates of immature birds, which is a prominent conservation concern due to the status of the species and the threats it currently faces throughout the northern Andes. Our citizen science-based study made it possible to gather, for the first time in Colombia, consolidated information on the status of the Andean Condor population using a standardised methodology to provide a reference for future counts and conservation actions, both at the national level and throughout the geographical range of the species.
... Vultures are essential to ecology because they clean up dead carcasses and give healthy habitats for other living beings, and because of this they are also known as "nature's cleanup crew" (1) . From a human perspective, vultures are the large birds of prey, nature's most successful obligate avian scavengers, providing us with an array of economic, https://www.indjst.org/ ...
Objective: The present study aimed to investigate the distribution and characteristics of nesting sites of Long-billed Vultures in the Barmer district of Rajasthan. The scientific study will be added to the conservation of the Indian Vulture, commonly known as the Long-billed Vulture (LBV) for saving the environment, ecological balance, and sustainability on a global platform. Methods: We investigated the distribution and nesting sites of LBV in the Barmer district by using direct or headcount methods (Supported by photographic and videographic counting). Findings: During the study period, a total of 12 sites were recorded, out of 7 nesting sites of LBV were observed with 14 nests recorded, and the characteristic nesting site was seen in hilly areas. In Barmer district 43 individuals of LBV were recorded in 12 sites with an average of 3.58 ± 2.57. Novelty: This study provides better zoological observational data on LBV about population and nesting sites in respective study areas. The finding of new nesting sites and nests in the hilly region of Barmer district (Aadupura Hills, Jhanpura, Bhilo ki Dhani, Gogaji Temple Hills, Juna Patrasar, Viratra Mata Hills, and Balera) is relevant to scholarly research. As we conclude the earlier studies suggest a higher population of LBV in the study area, but the present investigation reports a much smaller population than that reported earlier. The suggested study is fully relevant to the environment, ecological balance, and sustainability. Keywords: Long-billed Vulture, Distribution, Nesting sites, Hilly region, Barmer
... For every dollar that these farmers spend on nest boxes for kestrels, they save an estimated $84 to $357 in cherries (Shave et al. 2018). Scavenging raptors also perform the important service of carrion removal (Ogada et al. 2012, Buechley and Şekercioğlu 2016, Grilli et al. 2019, Plaza et al. 2020). The importance of vultures was highlighted during the 'Asian Vulture Crisis' in the late 1990s and early 2000s when vulture species across South Asia nearly went extinct due to veterinary use of diclofenac (Oaks et al. 2004, Pain et al. 2008. ...
Many of the world’s raptors, or birds of prey, are experiencing declines and are increasingly threatened with extinction. The State of the World’s Raptors provides a novel approach for setting priorities for the conservation of raptors across the globe. Biologists from The Peregrine Fund, the US Geological Survey, and the Zoological Society of London divided the world into 14 raptor conservation regions. They then determined priorities for raptor conservation based on the evolutionary distinctiveness and extinction risk of the species that occur in each region. Priorities for each raptor conservation region were documented in separate chapters, each of which was led by local raptor experts. The State of the World’s Raptors thus provides regional perspectives on global priorities to save raptors from extinction.
... Our results show that increased exposure can have a negative effect on livestock producers' perceived intangible benefits of black vultures such as consumption of carrion and control and reduction of the spread of diseases (Grilli et al., 2019). This may, in part, be due to perceived increase of black vulture populations. ...
Increasing wildlife tolerance (i.e., "the willingness of an individual to absorb the extra potential or actual costs of living with wildlife") can reduce human-wildlife conflict (HWC). Previous research shows how socio-cultural and psychological factors shape HWC, focusing on carnivores and charismatic species. Less-charismatic species, particularly non-mammals, have received less attention from both the scholarly and policy-making communities even though they may be socially, culturally, and ecologically important. This paper applies the Wildlife Tolerance Model (WTM) to examine livestock producers' interactions with a less-charismatic avian species, black vultures (Coragyps atratus), in the Midwestern USA, as an example of an emerging HWC in an agricultural landscape. We collected usable survey data from 168 livestock producers in Indiana and Kentucky and used a partial-least squares structural equation model to assess potential drivers of their tolerance of black vultures. Intangible costs (i.e., negative emotions associated with black vultures), utilitarian wildlife value orientations (WVOs), and tendency towards using more severe management actions were significantly associated with reduced tolerance. Intangible benefits (i.e., "non-monetary factors such as stress and fear") and mutualistic WVOs were significantly associated with increased tolerance. Importantly, tangible costs (i.e., "estimated economic costs associated with livestock losses due to wildlife predation") were not a significant predictor of black vulture tolerance. This paper highlights the importance of socio-cultural and psychological factors, rather than economic factors, in shaping people's tolerance of a less-charismatic avian species. It demonstrates the utility of WTM as a framework for assessing the economic, socio-cultural, and psychological drivers of less-charismatic avian species.
... Old and New World vultures play a crucial role in maintaining the ecosystem's health (Berlinguer et al 2021;Craig et al. 2018;Gangoso et al. 2013;Grilli et al. 2019;Morales-Reyes et al. 2018;Mateo-Tomás et al. 2017;Plaza et al. 2020;Santangeli et al. 2019). Being the only obligate scavengers among vertebrates, they efficiently remove carrion, curbing disease spread and reducing the potential for pathogen proliferation impacting both wildlife and domestic animals (Berlinguer et al. 2021;Plaza et al. 2020). ...
In the Anthropocene, recognising nature’s role in human well-being is pivotal for biodiversity conservation. Despite their significance, knowledge gaps persist regarding ecosystem services, even for well-studied species like vultures. Our study focuses on the Griffon Vulture Gyps fulvus in Sardinia, Italy, exploring their cultural and regulating services, including carcass disposal and resulting greenhouse gas (GHG) mitigation. Through surveys of natural reserve visitors and data on carcass provision and GHG emissions, we assess public perception, economic value, and environmental impacts associated with vultures. The public perception of Griffon Vultures is predominantly positive, with a strong acknowledgment of their role in disease prevention and carcass disposal, highlighting their contribution to regulation services. Furthermore, vultures are widely recognised as a key element characterising the agropastoral landscapes of Sardinia, underscoring their cultural importance. The economic evaluation, through willingness to pay for vulture-watching and photography opportunities, indicates a significant appreciation of these birds, with almost three-quarters of respondents willing to pay an entrance fee at vulture observation sites. We also show that supplanting the disposal role of vultures at studied feeding sites (during 2017–2022) would result in the emission of 96 tons of CO 2 equivalent, which highlights the critical role of vultures in climate mitigation. This study not only sheds light on the ecological and cultural significance of Griffon Vultures in Sardinia but also underscores the economic and environmental benefits of their conservation. It emphasises the need for continued efforts in vulture conservation, integrating ecological, cultural, and economic perspectives to foster a sustainable coexistence between humans and wildlife.
... roadkill), or due to lethal pest control (Englefield et al., 2018). Research into carcass use in Australia has focused primarily on defining and understanding intricate scavenger guilds that act as 'cleanup crews' (Grilli et al., 2019) across differing bioregions (Bragato et al., 2022;Vandersteen et al., 2023). Within these bioregions, several species-specific studies have examined in-depth spatiotemporal scavenging dynamics and behaviours of dominant scavenging taxa including corvids (Bragato et al., 2022) and dingoes (Spencer et al., 2021) (Canis dingo). ...
Brushtail possums (Trichosurus vulpecula) are becoming increasingly recognized as key members of local scavenger guilds in Australia. Yet, our understanding of the spatiotemporal scavenging dynamics of this mainly herbivorous marsupial species remains limited. We investigated abiotic and biotic factors influencing possum carcass use across an alpine and temperate bioregion in Australia. Using camera traps set on experimentally placed kangaroo carcasses , we first examined the influence of both open and closed canopy habitats and warm and cool seasons on possum scavenging behaviour across both bioregions. While scavenging was minimal in open habitats across both biore-gions-likely a reflection of possums being an arboreal species-seasonality did significantly influence possum activity. Possums scavenged on carcasses in temperate regions entirely during cooler months. Scavenging was recorded year-round in the alpine region, but with total possum feeding time on carcasses 5.9 times higher in cooler months. A more detailed 12-month study in the alpine region confirmed this strong seasonal influence on possum scavenging, with possums up to 5.4 times more likely to discover carcasses in winter and spend up to 6.7 times longer feeding on carcasses during this season. The variability in possum scavenging behaviour between bioregions and seasons highlights the spatiotemporal complexity of possum scavenging behaviour and the importance of considering abiotic and biotic factors to understand the behaviours of scavengers more broadly. Recognizing primarily herbivorous animals as important yet often overlooked members of local scavenger guilds can help advance our understanding of complex scavenging networks and the intricate pathways through which energy flows in ecosystems, both in Australia and in other systems. Improving our understanding of the spatiotemporal scavenging dynamics of typically herbivorous species may also help to inform more nuanced and effective wildlife management strategies, where supplementary foraging on atypi-cal food resources poses conservation concerns. K E Y W O R D S abiotic and biotic factors, carrion, herbivore, mesoscavengers, scavenger
... Moreover, EMV of ESs-NC meaningfulness relies on its capability of revealing the often unsuspected value of Nature, allowing us to assess what is "apparently invisibly" valuable or traditionally viewed as not valuable. Examples include the seagrass sanitation effect that promotes human health (Ascioti et al., 2022), the carrions' scavengers that help keep zoonosis under control (Grilli et al., 2019;Frank and Sudarshan, 2023), and the substantial reduction of deforestation that may prevent or minimize the impacts of zoonotic pandemics (Bernstein et al., 2022), the natural predators capable of controlling edible fruits' pests (Daniels et al., 2017), the many forests' hidden services (Cavender-Bares et al., 2022), and a plethora of others (Zhang, 2019 and the references quoted therein). Furthermore, EMV of ESs-NC may show what is not genuinely economically convenient once "externalities" are appropriately accounted for (TrueCost-TEEB 2013) and how globally significant the impacts of natural and/or human-induced hazards are (Turberlin et al., 2023). ...
... Among the raptors that consume carrion, including Accipitriformes, Cathartiformes, and Falconiformes, research on carrion removal services has primarily focused on facultative scavengers within the Accipitriformes (Table SM1). The relative lack of studies on vulture carrion removal in urban ecosystems compared to rural ones (DeVault et al. 2003;Grilli et al. 2019) may stem from their lower populations due to the high sensitivity of obligate scavengers to intense human impact, prevalent in the urban studies reviewed, although they benefit from moderate human impact as seen in some African countries (Buechley et al. 2018;Sebastián-González et al. 2019;McPherson et al. 2021a). These obligate scavengers, characterized by their large bodies and wingspans (DeVault et al. 2003), do not possess the traits typically associated with "archetypal urban raptors", such as caused by expanding human populations and urban areas in the countryside of Africa and Asia, it would be logical to expect a greater proportion of studies on negative interactions between humans and raptors in these continents. ...
In an increasingly urbanized world, some raptors successfully colonize and thrive in urban environments, leading to more frequent interactions with humans. These interactions can be either positive, such as providing ecosystem services, or negative, resulting in human-wildlife conflicts. Despite growing literature on these interactions, a comprehensive review focusing on urban environments has been lacking. This study aimed to address this gap by conducting a systematic review using Google Scholar and the Scopus bibliographic database. A total of 45 studies met the search criteria, with a predominant prevalence of the northern hemisphere. Accipitriformes was the most studied order of raptors (50%), followed by Strigiformes (37%), Falconiformes (8%), and Cathartiformes (2%). Positive interactions studied included cultural services, pest control, positive perception, carrion removal, while negative interactions involved safety damage, property damage, negative perception, disease transmission, livestock damage, nuisance and superstitions. Pest control and cultural services were supported by the evidence, although only for specific orders. Carrion removal and aggressiveness appear to decrease with urbanization, although more studies are needed to verify this premise. Both positive and negative perceptions were evident, influenced in part by the knowledge or closeness that people had towards urban raptors. We discuss how the interactions studied influence the daily lives of citizens and, in turn, how human activities shape and influence these interactions. Finally, given that cities are socio-ecological systems, we advocate for methodologies that integrate the social aspects of human-predator interactions along with ecological ones to promote coexistence.
... Poaching due to human conflicts over wildlife, actual or perceived, is an important threat to large raptors worldwide 9,64-68 , such as Crowned Eagles 69 , Harpy Eagles (Harpia harpyja) 70 , and Andean Condors (Vultur gryphus) 65,66 , even resulting in species extinction 67 . Raptors provide important ecosystem services by controlling pests in crops and urban areas and cleaning the environment of organic material [71][72][73] . Local population extinction and decline of predators due to anthropogenic threats may result in trophic cascades, with severe consequences for human well-being 14,15,[74][75][76] . ...
Conflicts between rural people and the Endangered Black-and-chestnut Eagle (Spizaetus isidori) are a prominent conservation concern in the northern Andes, as at least 60 eagles were poached between 2000 and 2022 in response to poultry predation. Here, we conducted direct observations to analyze the Black-and-chestnut Eagle diet and evaluated how forest cover affects the feeding habits of the species during nestling-rearing periods in 16 nests located in different human-transformed Andean landscapes of Ecuador and Colombia. We analyzed 853 prey items (46 species) delivered to nestlings. We used Generalized Linear Models to test whether the percent forest cover calculated within varying buffer distances around each nest and linear distances from the nest to the nearest settlement and pasture areas were predictors of diet diversity and biomass contribution of prey. Forest cover was not a factor that affected the consumption of poultry; however, the eagle regularly preyed on chickens (Gallus gallus) (i.e., domestic Galliformes) which were consumed by 15 of the 16 eagle pairs, with biomass contributions (14.57% ± 10.55) representing 0.6–37% of the total prey consumed. The Black-and-chestnut Eagle is an adaptable generalist able to switch from mammalian carnivores to guans (i.e., wild Galliformes) in human-dominated landscapes, and eagles nesting in sites with low forest cover had a less diverse diet than those in areas with more intact forests. Management actions for the conservation of this avian top predator require studies on the eagle’s diet in areas where human persecution is suspected or documented, but also maintaining forest cover for the wild prey of the species, development of socio-economic and psychological assessments on the drivers behind human-eagle conflicts, and the strengthening of technical capacities of rural communities, such as appropriate poultry management.
... These unique traits allow vultures to play multifunctional roles in the ecosystem (Bildstein, 2022). For example, vultures have been labelled as "nature's clean-up crew" because they can consume significant amounts of organic material (i.e., carrion), making them essential recyclers in nature (Chen et al., 2023;Grilli et al., 2019). Further, consumption of carrion by vultures is likely to disrupt the transmission of diseases from infected animals to humans, thus playing a pivotal public health role via disease control (Jalihal et al., 2022;Van Den Heever et al., 2021). ...
Environmental factors, such as climate change and anthropogenic activities, constitute the principal drivers behind the global decline of avian scavengers. In this context, understanding and predicting the impact of environmental factors on species distribution at different geographic scales is essential for identifying priority areas with significant suitable habitats for conservation. Using ensemble Species Distribution Modelling (eSDM) with georeferenced occurrence records from Ghana, this study shows that area of suitable habitats for the critically endangered Hooded Vulture (Necrosyrtes monachus) will decline under specific future climate scenarios (2060, 2080, and 2100). In particular, declines will be much higher and more rapid under fossil-fuelled development (SSP585) than in the middle of the road (SSP245) and sustainable (SSP126) climate scenario pathways, which will experience a relative increase in suitable habitats. Land use (specifically, urban areas/sparse vegetation) and precipitation in the wettest month (bio13) are the most important contributors to Hooded Vulture spatial distribution. eSDM predictions suggest that suitable habitats will contract in the South and shift up North under future climate scenarios. Further, a substantial proportion of suitable habitats (approximately 78%) lie outside the country’s protected area network, with the few represented expected to decline by the turn of the century. The approach of this study and the results appear valuable for identifying, monitoring, and intensifying conservation planning efforts in priority areas by scientists and decision-makers toward the protection of the threatened Hooded Vulture in Ghana.
... comm.). The value of their ecosystem services is much greater; for example, the economic value of the sanitation services provided by Turkey Vultures Cathartes aura has been estimated at US$700 million per annum (Grilli et al. 2019). Although the contribution of vultures to the economics of human health and veterinary care has not yet been quantified in Africa, efforts to conserve vultures should not be deterred ( Van den Heever et al. 2021). ...
We report how an extreme weather event in Freetown, Sierra Leone, on 24 May 2023, destroyed an iconic Cotton Tree or Kapok Ceiba pentandra and resulted in the mass slaughter of c. 100 Hooded Vultures Necrosyrtes monachus. Rain soaked, grounded birds were caught by hand, slaughtered and prepared for human consumption. One bird was rescued and subsequently released. The Cotton Tree formed the focal point around which Freetown was founded in 1792, and this contributes to the underlying issues of mythology and symbolism associated with the event. We suggest that awareness campaigns are required to communicate the valuable clean-up services provided by Hooded Vultures in urban environments in Sierra Leone and across West Africa.
... Turkey Vultures are efficient foragers, relying on a highly sensitive sense of smell to locate food items across a range of landscapes (Grigg et al. 2017), where they have been documented consuming a variety of food items: carcasses of terrestrial mammals (including domestic mammals), birds (including domestic birds), reptiles, amphibians, fish, and arthropods (Paterson 1984, Hiraldo et al. 1991, Buckley 1996, Ballejo et al. 2018. In ,1% of their distribution, they are responsible for removing 1,000 tons of organic material per year (Grilli et al. 2019), and thus provide a vital ecosystem service. Turkey Vultures also feed at anthropogenic sites such as landfills (Torres-Mura et al. 2015, Augé 2017, Noreen and Sultan 2021, so increasing human development could have a positive effect on Turkey Vultures (de Araujo et al. 2018). ...
... According to Margalida and Colomer (2012), the Spanish vulture population removes on average 134-201 metric tonnes of bones and 5551-8326 metric tonnes of flesh every year, saving at the very least $1.19 million to $1.94 million. Similarly, Turkey Vultures (Cathartes aura) removed 1000 t of organic material every year, a monetized service worth more than US$ 500,000, which may amount to US$ 700 million per year for the entire world's Turkey Vultures population (Grilli et al., 2019). In our study area, we did not encounter any major scavenging moments by vultures, as once we encountered red-headed vulture scavenging on nilgai carcasses (Panda et al., 2023a). ...
In human-dominated landscapes, quantifying ecosystem services in terms of economic benefits could contribute to establishing peaceful coexistence between humans and large carnivores. In this study, we estimated the monetary value of scavenging benefits provided by striped hyenas (Hyaena hyaena) in an anthropogenic landscape in the semi-arid region of Rajasthan, India. We converted the value of domestic livestock carcasses consumed by striped hyenas from opportunity costs to quantify the value of this important ecosystem service to local people.
We determined the monetary value of carcass disposals using two methods, including (1) electric cremation, and (2) pyre burning of animal carcasses. To determine the minimum number of striped hyenas, present in the study area, we employed a photo-capture approach, and we used scat analysis to determine the livestock consumed by striped hyenas. We estimated that striped hyenas removed 23.13 tons (4.4 %) of livestock carcass waste from the
total of 525.68 tons of waste generated per year in the Intensive Study Area (ISA). The annual monetary value of livestock carcass waste removal by striped hyenas in the ISA was estimated to be ~US 49,665 for pyre burning. Our study demonstrates the economic benefit of scavenging services provided by striped hyenas in areas where anthropogenic food is abundant. In such areas, as hyenas scavenge anthropogenic food, local communities benefit from waste management. Using alternative carcass disposal methods
without striped hyenas would be expensive and likely environmentally damaging.
... Carcass mass is also highly relevant to medicolegal death investigation as human decedents of all sizes can undergo decomposition. Ultimately, the consideration of CDIs and their role in the function of terrestrial ecosystems [5,88,89] is crucial to the development of forensic taphonomy as a discipline, and it is hoped that the current observations will help stimulate continued research into carrion ecology [22,[90][91][92]. Fig. 7. Cadaver Decomposition Island (CDI) characteristics of decomposing pig (Sus scrofa domesticus) carcasses at a tropical taphonomy facility in Honolulu, HI, USA. ...
Decomposition studies have been conducted in several regions of the world, but relatively few have investigated taphonomy in tropical environments. Even fewer have explored carcass decomposition during multiple tropical seasons, leaving the relationships between season and decomposition in tropical environments poorly understood. Ten decomposition studies using 30 carcasses were conducted in Honolulu, Hawaii, USA to start addressing this knowledge gap. These studies show that some postmortem processes were observed regardless of season. Carcass temperature and chemistry were spatiotemporally variable. Fly larval masses were consistently observed within 3 days (∼75 ADD) postmortem and carcasses lost 60%–90% of mass by 10 days (∼250 ADD) postmortem (Total Body Score ∼26). Season had a significant effect on decomposition, yet the warmest and most humid seasons did not always result in the most rapid and extensive decomposition. Seasonal variation appears to be less pronounced than at other tropical decomposition sites.
... The ecosystem services of birds, and in particular birds of prey, have recently garnered increasing attention (Donázar et al. 2016;Peisley et al. 2017;Graña Grilli et al. 2019), not least because bird-ecosystem interactions were often neglected or only cursorily treated in the past, for instance due to mammal-oriented research agendas. This 'mammal bias' is perhaps especially pronounced in palaeoecology and Pleistocene zooarchaeology, where scholars traditionally focused on ungulates and proboscideans since these animals allegedly constituted the primary source of calories and raw materials for early hominins (cf. ...
Of all avian groups, birds of prey in particular have long been a prominent subject of fascination in many human societies. This book demonstrates that the art and materiality of human engagements with raptors has been significant through deep time and across the world, from earliest prehistory to Indigenous thinking in the present day. Drawing on a wide range of global case studies and a plurality of complementary perspectives, it explores the varied and fluid dynamics between humans and birds of prey as evidenced in this diverse art-historical and archaeological record.
From their depictions as powerful beings in visual art and their important roles in Indigenous mythologies, to the significance of their body parts as active agents in religious rituals, the intentional deposition of their faunal remains and the display of their preserved bodies in museums, there is no doubt that birds of prey have been figures of great import for the shaping of human society and culture. However, several of the chapters in this volume are particularly concerned with looking beyond the culture–nature dichotomy and human-centred accounts to explore perspectival and other post-humanist thinking on human–raptor ontologies and epistemologies. The contributors recognize that human–raptor relationships are not driven exclusively by human intentionality, and that when these species meet they relate-to and become-with one another. This ‘raptor-with-human’-focused approach allows for a productive re-framing of questions about human–raptor interstices, enables fresh thinking about established evidence and offers signposts for present and future intra-actions with birds of prey.
... One of the key ecosystem functions that ravens and other scavengers provide is the fast consumption of carrion (Mateo-Tomás et al., 2017;Grilli et al., 2019), thereby reducing disease transmission (Szcodronski and Cross, 2021). It has been suggested that scavengers in the GYE reduce the risk of brucellosis transmission from livestock to elk by quickly consuming infected aborted biological materials (Szcodronski and Cross, 2021). ...
Anthropogenic food subsidies can alter ecosystem processes, such as competition, predation, or nutrient transfer, and may strongly affect protected areas. Increasing recreation and ecotourism often create food subsidies, especially in the surrounding lands through fast-growing gateway communities. How the effects of these subsidies extend into protected areas when animals move across boundaries remains largely unexplored. We addressed this question by studying the movement and foraging of common ravens ( Corvus corax) , opportunistic scavengers that are well known to feed on predator kills and on anthropogenic food subsidies. We analyzed spatiotemporal data from 57 global positioning system (GPS)-tagged ravens, trapped within or close to Yellowstone National Park, to study their seasonal use of natural and anthropogenic food sources. Although Yellowstone National Park contains a full suite of native predators and ravens can be observed at virtually every kill site, we show that anthropogenic subsidies were utilized to a much greater extent than other natural resources, especially during winter. Important subsidies included gut piles of harvested game animals left by hunters, fat present on wastewater settling ponds, roadkill, and waste from agricultural and urban activities. These subsidies were distributed over vast areas beyond Yellowstone National Park. During fall/winter, ravens traveled longer distances (21.9 vs. 13 km) and spent more time outside Yellowstone National Park (73% of GPS points outside), mostly feeding on anthropogenic subsidies, than in spring/summer (42% of GPS points outside). This difference between seasons was more pronounced for individuals holding territories within the protected area than for those without territories. The large area over which ravens used anthropogenic food subsidies (within more than 100 km of Yellowstone National Park) affects the park’s raven population and the scavenging services they provide. We suggest that the scale of resource use must be considered by managers seeking to control expanding raven populations elsewhere.
... For example, abundance and diversity of raptors (sensu McClure et al. 2019) is associated with increased biodiversity (Sergio et al. 2005(Sergio et al. , 2006. Raptors are often used as indicators of environmental health (Sergio et al. 2008), and provide cultural and ecosystem services (Markandya et al. 2008, Donázar et al. 2016, O'Bryan et al. 2018, Grilli et al. 2019, Aguilera-Alcalá et al. 2020. ...
Potential extinction of raptor species is especially important given their outsized roles in ecosystems and human cultures. We examined Red List data for raptor species listed as critically endangered by the International Union for the Conservation of Nature. Our goal was to highlight the plight of these critically endangered raptor species while identifying the reasons for their imperiled status, the most important countries for their conservation, and the actions needed for their persistence. We categorized the 17 critically endangered raptor species into two groups—Accipitrid vultures and species with small populations. Accipitrid vultures had relatively large populations and ranges, and were listed under Criterion A due to precipitous population declines. The threat listed for the most Accipitrid vultures was “pollution,” reflecting poisoning as the principal cause of declines. Conversely, the small population species were listed under Criteria C and D and were most threatened by “agriculture and aquaculture.” Countries in Africa and south Asia were hotspots of critically endangered raptors. The conservation action listed for the most species was “education and awareness” followed by “land protection” and “law and policy.” The most-listed monitoring category was “population trends.” The Multi-species Action Plan to Conserve African-Eurasian Vultures should be implemented to prevent extinction of Accipitrid vultures. Conversely, species with small populations are generally isolated and must be managed individually. Conservation of the world's most imperiled raptor species is an important facet of assuaging the sixth mass extinction.
... However, scavenging is present in many taxa, from obligate and facultative large vertebrate scavengers capable of consuming a whole carcass in one feeding event (Mateo-Tomás et al. 2017), to invertebrate scavengers that can aggregate around carrion in the thousands (Forbes and Carter 2015). Together, these species form scavenger guilds which, in addition to acting as 'natures clean-up crew' (Grilli et al. 2019), also support critical linkages, structure, and stability in food webs (Wilson and Wolkovich 2011); distribute nutrients within and among ecosystems; and provide economic and human health benefits related to carcass disposal and sanitary measures (Beasley et al. 2019). ...
Context
Carrion is a high-energy and nutrient-rich resource that attracts a diverse group of vertebrate scavengers. However, despite the carrion pool being highly seasonal in its availability, there is little understanding of how scavengers utilise carcasses across all four seasons.
Aim
To assess how season influences carcass-detection times by vertebrate scavengers and their rates of scavenging.
Methods
We used remote cameras to monitor vertebrate scavenging at 15 eastern grey kangaroo (Macropus giganteus) carcasses in four consecutive seasons (summer, autumn, winter, and spring; total 58 carcasses) in the Australian Alps.
Key results
In total, 745 599 remote-camera images were captured, within which 34 vertebrate species were identified, nine of which were recorded to actively scavenge. Time to first detection of carcasses by vertebrate scavengers was 5.3 and 9.6 times longer during summer (average 144 h) than during spring (average 34 h) and winter (average 24 h) respectively. Rates of vertebrate scavenging were highest in winter and spring, with brushtail possums (Trichosurus vulpecula) accounting for 78% of all scavenging events during winter, and ravens (Corvus spp.) accounting for 73% during spring. High rates of carcass use by these mesoscavengers may reflect a scarcity of other food sources, the demands of their breeding season, or a relative absence of scavenging by larger dominant species such as dingoes (Canis dingo) and wedge-tailed eagles (Aquila audax).
Conclusions
These findings demonstrate the highly seasonal nature of vertebrate scavenging dynamics in an alpine ecosystem, and that mesoscavengers, not apex scavengers, can dominate the use of carcasses.
Implications
Accounting for the effects of season is integral to understanding the way animals utilise carcasses in alpine and other strongly seasonal environments; and for developing further our knowledge of ecosystem processes linked to decomposition.
... Although scavengers provide ecosystem services by removing decomposing carcasses (Grilli et al., 2019;Markandya et al., 2008), in some circumstances, scavengers also might act as pathogen vectors by transporting infectious materials to other areas. For example, though vultures are thought to be particularly well-suited to inhibit disease spread when consuming carrion by utilizing highly acidic stomach secretions that destroy nearly all microbes (Houston & Cooper, 1975) and might greatly reduce the chance of infection from a decomposing carcass (Ogada, Keesing, & Virani, 2012), some microbes can survive the vulture digestive tract and be regurgitated or passed through feces (Houston & Cooper, 1975). ...
Scavenging plays a vital role in maintaining ecosystem health and contributing to ecological functions; however, research in this sub-discipline of ecology is underutilized in developing and implementing wildlife conservation and management strategies. We provide an examination of the literature and recommend priorities for research where improved understanding of scavenging dynamics can facilitate the development and refinement of applied wildlife conservation and management strategies. Due to the application of scavenging research broadly within ecology, scavenging studies should be implemented for informing management decisions. In particular, a more direct link should be established between scavenging dynamics and applied management programs related to informing pharmaceutical delivery and population control through bait uptake for scavenging species, prevention of unintentional poisoning of nontarget scavenging species, the epidemiological role that scavenging species play in disease dynamics, estimating wildlife mortalities, nutrient transfer facilitated by scavenging activity, and conservation of imperiled facultative scavenging species. This commentary is intended to provide information on the paucity of data in scavenging research and present recommendations for further studies that can inform decisions in wildlife conservation and management. Additionally, we provide a framework for decision-making when determining how to apply scavenging ecology research for management practices and policies. Due to the implications that scavenging species have on ecosystem health, and their overall global decline as a result of anthropic activities, it is imperative to advance studies in the field of scavenging ecology that can inform applied conservation and management programs.
... In addition to increasing our understanding of vulture species, behavioural studies on vultures can also yield useful information for conservation marketing, whereby social-marketing strategies are applied to conservation issues with the aim of influencing people's behaviour to benefit biodiversity conservation (Ryan et al. 2020). For example, numerous studies have highlighted the ecological importance of vultures (Ogada et al. 2012b;Hill et al. 2018;Van den Heever et al. 2021), their cultural value (Craig et al. 2018;Boakye et al. 2019;Mashele et al. 2021b) and the economic worth of the ecosystem services vultures provide (Becker et al. 2005;Markandya et al. 2008;Grilli et al. 2019). However, little attention has been paid to the behavioural repertoire of vultures, such as the 'exceptional' copulatory behaviour of certain vulture species (Donázar et al. 1994), the parental care displayed by adult vultures (Maphalala and Monadjem 2017), and how vultures may defend their nest sites against competitors (Thompson et al. 2019). ...
Most vulture species worldwide are in decline and of conservation concern. Despite the growing attention to vultures, relatively few studies have focused on their breeding behaviour. Understanding all aspects of a species’ behaviour and its behavioural needs could help to inform conservation efforts. Behavioural studies can be enhanced with the use of an ethogram that clearly defines and describes distinct behaviours. We present the first ethogram detailing the nesting and breeding behaviours of the Critically Endangered Hooded Vulture Necrosyrtes monachus, compiled from over 400 000 nest camera photographs and from hours of direct personal observations at nests in north-eastern South Africa. We describe 28 behaviours that Hooded Vultures exhibited in and around their nests, and these fell into five discrete categories: Movement, Resting, Body Care, Social, and Nesting. We also present 34 camera trap images depicting behaviours from within each category, and discuss the uses and limitations of behaviour-recording technologies. Many of these behavioural elements may be common across vulture species, and so this ethogram may be a useful starting point for other researchers studying vultures globally.
... These ecosystems are communities involving biotic and abiotic interactions, all parts of which are necessary for ecosystem functionality, as well as providing ecosystem services (e.g. pollination of crops, pest control and biomass production) to humans (Semmens et al., 2018;Grilli, Bildstein & Lambertucci, 2019;Wotton et al., 2019). Importantly, migratory animals may have significant roles in ecosystems thousands of kilometres apart, where they reside for several hours to several months (L opez-Hoffman et al., 2017). ...
Global movement patterns of migratory birds illustrate their fascinating physical and physiological abilities to cross continents and oceans. During their voyages, most birds land multiple times to make so‐called ‘stopovers’. Our current knowledge on the functions of stopover is mainly based on the proximate study of departure decisions. However, such studies are insufficient to gauge fully the ecological and evolutionary functions of stopover. If we study how a focal trait, e.g. changes in energy stores, affects the decision to depart from a stopover without considering the trait(s) that actually caused the bird to land, e.g. unfavourable environmental conditions for flight, we misinterpret the function of the stopover. It is thus important to realise and acknowledge that stopovers have many different functions, and that not every migrant has the same (set of) reasons to stop‐over. Additionally, we may obtain contradictory results because the significance of different traits to a migrant is context dependent. For instance, late spring migrants may be more prone to risk‐taking and depart from a stopover with lower energy stores than early spring migrants. Thus, we neglect that departure decisions are subject to selection to minimise immediate (mortality risk) and/or delayed (low future reproductive output) fitness costs. To alleviate these issues, we first define stopover as an interruption of migratory endurance flight to minimise immediate and/or delayed fitness costs. Second, we review all probable functions of stopover, which include accumulating energy, various forms of physiological recovery and avoiding adverse environmental conditions for flight, and list potential other functions that are less well studied, such as minimising predation, recovery from physical exhaustion and spatiotemporal adjustments to migration. Third, derived from these aspects, we argue for a paradigm shift in stopover ecology research. This includes focusing on why an individual interrupts its migratory flight, which is more likely to identify the individual‐specific function(s) of the stopover correctly than departure‐decision studies. Moreover, we highlight that the selective forces acting on stopover decisions are context dependent and are expected to differ between, e.g. K−/r‐selected species, the sexes and migration strategies. For example, all else being equal, r‐selected species (low survival rate, high reproductive rate) should have a stronger urge to continue the migratory endurance flight or resume migration from a stopover because the potential increase in immediate fitness costs suffered from a flight is offset by the expected higher reproductive success in the subsequent breeding season. Finally, we propose to focus less on proximate mechanisms controlling landing and departure decisions, and more on ultimate mechanisms to identify the selective forces shaping stopover decisions. Our ideas are not limited to birds but can be applied to any migratory species. Our revised definition of stopover and the proposed paradigm shift has the potential to stimulate a fruitful discussion towards a better evolutionary ecological understanding of the functions of stopover. Furthermore, identifying the functions of stopover will support targeted measures to conserve and restore the functionality of stopover sites threatened by anthropogenic environmental changes. This is especially important for long‐distance migrants, which currently are in alarming decline.
... The Griffon Vulture is an obligate scavenger, exclusively feeding on carcasses of livestock and wild ungulates (Cramp & Simmons 1980), thus providing critical ecosystem services (Pain et al. 2003, Grilli et al. 2019. It relies on food resources, which are spatially and temporally unpredictable. ...
The spatial ecology of the Eurasian Griffon Vulture (Gyps fulvus) has been a subject of scientific interest for long due to its conservation status, critical ecosystem role, gregarious lifestyle and complex foraging behavior. The trans-border Eastern Rhodope Mountain in Bulgaria and Greece holds an increasing population of the species and one of the largest on the Balkan Peninsula. We used high-frequency GPS data from 13 Griffon Vultures from this population to study their movements, home range size and its seasonal or age specific dynamics. The overall foraging home range (95% kernel) was 3,204 km2 and the core area of activity (50% kernel) was 256.5 km2. We found high seasonal variation of the home range size. Vultures were foraging over larger areas in the summer and spring but their activity was limited to four times smaller areas in winter. We found no age specific variation in the home range sizes but the non-adult vultures showed tendency to conduct exploratory movements far from the breeding colony. Our results can be used for planning conservation efforts in the areas of high importance for the species.
... Cultural keystone species are plants and animals that can be used to measure human health and well-being, because of their vital link to a particular culture (Cristancho and Vining, 2004;Garibaldi and Turner, 2004). Vultures are recognized worldwide for the ecosystem services (cleaning, nutrient cycling, cultural) they provide (Gangoso et al., 2013;Grilli et al., 2019;Morales-Reyes et al., 2019), for their aesthetic value (Becker et al., 2005;Morelli et al., 2015;Aguilera-Alcalá et al., 2020), and for their important roles in African traditional medicine . The use of African vultures as cultural keystone species could bridge gaps between ecological and socio-cultural systems that undermine current vulture conservation efforts (Horgan et al., 2021). ...
African vulture populations are rapidly declining, yet funding and other resources available for their conservation are limited. Improving our understanding of which African vulture species could best serve as an umbrella species for the entire suite of African vultures could help conservationists save time, money, and resources by focusing
their efforts on a single vulture species. Furthermore, improving our understanding of the suitability of African vultures as biomonitors for detecting environmental toxins could help conservation authorities to detect changes in ecosystem health. We used a systematic approach based on criteria selected a priori to objectively evaluate the
potential of each of the 10 resident African vulture species as (i) an umbrella species for all of the African vulture species, and (ii) an avian biomonitor. For each criterion, we scored the respective African vulture species and summed the scores to determine which species was best suited as an umbrella species and as an avian biomonitor.
Our results showed that, overall, certain aspects of vulture ecology (large population sizes, large body sizes, long lifespans, and their ability to be monitored over numerous seasons) support their suitability as biomonitors, while other ecological traits, including
their diets and the public’s perceptions of vultures, could diminish their suitability. The White-backed Vulture (Gyps africanus) was the best fit of the 10 vulture species in our assessment as both an avian biomonitor and an umbrella species for all African vulture species. Meanwhile, significant knowledge gaps for other species inhibit their
utility as biomonitors. Due to their large home-range sizes, African vultures may only be useful as biomonitors at a regional scale. However, there could be value in using the White-backed Vulture as an umbrella species, as an aid to conserve the entire suite of African vulture species.
... Vultures are among the most threatened avian groups in the world 46,47 , and face not only threats such as poisoning with pesticides 37,48 and lead contamination 49,50 , but also persecution, trading of parts and food shortage 47 . This is a cause for concern given the important regulating ecosystem services that these species provide, removing organic material from the environment, which in turn could be important for public health and economy 51,52 . Most of the named threats are triggered by conflict between vultures and livestock producers 19,30,37 . ...
Content published on social media may affect user’s attitudes toward wildlife species. We evaluated viewers’ responses to videos published on a popular social medium, focusing particularly on how the content was framed (i.e., the way an issue is conveyed to transmit a certain meaning). We analyzed videos posted on YouTube that showed vultures interacting with livestock. The videos were negatively or positively framed, and we evaluated viewers’ opinions of these birds through the comments posted. We also analyzed negatively framed videos of mammalian predators interacting with livestock, to evaluate whether comments on this content were similar to those on vultures. We found that the framing of the information influenced the tone of the comments. Videos showing farmers talking about their livestock losses were more likely to provoke negative comments than videos not including farmer testimonies. The probability of negative comments being posted on videos about vultures was higher than for mammalian predators. Finally, negatively framed videos on vultures had more views over time than positive ones. Our results call for caution in the presentation of wildlife species online, and highlight the need for regulations to prevent the spread of misinformed videos that could magnify existing human-wildlife conflicts.
... For instance, by removing carcasses and other organic material from the environment they may limit the increase and spread of microorganisms, thereby providing disease regulation services (Plaza et al., 2020; Figure 2). The removal of carcasses by vultures saves millions of dollars globally and prevents greenhouse gas emissions produced by artificial carcass collection, transport and incineration (Grilli, Bildstein, & Lambertucci, 2019;Morales-Reyes et al., 2015). In addition, by consuming carcasses they may regulate populations of mesocarnivores and opportunistically scavenging pest species (Markandya et al., 2008 Vultures also provide income from tourism as people travel to many places in the world to see them. ...
Vultures and condors are among the most threatened avian species in the world due to the impacts of human activities. Negative perceptions can contribute to these threats as some vulture species have been historically blamed for killing livestock. This perception of conflict has increased in recent years, associated with a viral spread of partial and biased information through social media and despite limited empirical support for these assertions. Here, we highlight that magnifying infrequent events of livestock being injured by vultures through publically shared videos or biased news items negatively impact efforts to conserve threatened populations of avian scavengers. We encourage environmental agencies, researchers, and practitioners to evaluate the reliability, frequency, and context of reports of vulture predation, weighing those results against the diverse and valuable contributions of vultures to environmental health and human well‐being. We also encourage the development of awareness campaigns and improved livestock management practices, including commonly available nonlethal deterrence strategies, if needed. These actions are urgently required to allow the development of a more effective conservation strategy for vultures worldwide.
... Vultures are obligate scavengers which provide important ecosystem services. By consuming carcasses, they contribute to waste disposal, nutrient cycling and limit the spread of diseases (Pain et al. 2003;Markandya et al. 2008;Grilli et al. 2019). In Europe, changes in livestock husbandry practices, improvement of veterinary care and sanitary regulations dealing with animal by-products' disposal have caused reduction in the availability of food for vultures (Tella 2001;Olea and Mateo-Tomas 2009). ...
Full text available here: https://rdcu.be/cfxJS.
Supplementing vulture populations with carcasses disposed at feeding stations is a common management and conservation practice worldwide. However, there is a lack of knowledge on the dependence of large vultures on the supplementary feeding stations (SFS) in areas with high abundance of natural food. We tagged 11 Griffon Vultures (Gyps fulvus, Hablizl 1783) with GSM/GPS transmitters in the Eastern Rhodopes, Bulgaria and studied the seasonal dynamic of feedings at SFS and at occasional carcasses found in the field. We used combination of remote sensing and field inspections to identify the vulture feeding events. Our results show that most of the feeding events occurred at occasional carcasses found in the wild (77.4%), whereas only 22.6% were at SFS, but high seasonal variation was observed. Vulture’s reliance on feeding stations was lowest in summer (19.82 ± 7.8%) and highest in winter when 56.5 ± 16.1% of the feedings were at the SFS. Griffon Vultures travelled longer daily distances in days feeding in the wild compared to days when they were not feeding or were visiting SFS. Our study indicates that in habitats with high abundance of natural food (free-range livestock and game), vultures tend to actively forage and use feeding stations as supplemental sources of food, mostly during long periods of adverse weather or in winter when foraging conditions are worse and natural food is less abundant.
... Old World vultures are one of the most threatened avian guilds and have experienced a rapid decline over the past few decades, especially in Africa and Asia (Chaudhary et al. 2012, Ogada et al. 2015, Buechley & Şekercioğlu 2016. As the only obligate vertebrate scavengers, vultures provide crucial ecosystem services (Ogada et al. 2012, Moleon et al. 2014, Grilli et al. 2019. Their extinction would negatively affect the natural processes in the ecosystems and entail substantial financial costs and increased greenhouse gas emissions from transportation and incineration of carcasses (Buechley & Şekercioğlu 2016, Morales-Reyes et al. 2015. ...
Capsule
The Eurasian Griffon Vulture Gyps fulvus is an obligate scavenger relying on spatially and temporally unpredictable food resources. We demonstrate how high-frequency telemetry data can be efficiently used to identify vultures’ feeding locations in the wild and study their diet.
Aims
To study the Griffon Vulture diet composition, seasonal variations, and bathing frequency in an area with high natural food availability.
Methods
We used a remote-sensing technique based on GPS and accelerometry data to identify the feeding locations, and ground-truthing to identify the carcass species and investigate the causes of mortality.
Results
We identified 13 taxa in the diet of Griffon Vultures. Cattle comprised 48.5% of the diet, followed by sheep (24.3%), while wild animals were 13.1%. We observed seasonal variation in the proportion of small stock and game species in the diet. Predation was reported as the main cause of mortality (60.2%) for prey species, while natural causes accounted for 37.6%. Vultures were mainly feeding in areas south of their breeding colonies in Bulgaria and Greece. Natural springs and fountains were regularly used by the Griffon Vultures for bathing and drinking, especially in the summer.
Conclusions
Free-ranging livestock creates favourable feeding conditions for vultures, especially in areas with rugged terrain and a high density of predators. An increase in the number of wild ungulates can potentially buffer the fluctuations in livestock numbers and be beneficial for vultures, especially in the autumn and winter months. Lead ammunition must be substituted with non-toxic alternatives to reduce the exposure of vultures and other scavengers to lead poisoning.
... Indeed, declines in raptor populations during the mid-20th century highlighted the dangers of organochlorine pesticides (e.g., Hickey 1969, Grier 1982, Henny et al. 2010, and population levels of raptors can indicate areas of high biodiversity (Sergio et al. 2005(Sergio et al. , 2006. Turkey Vultures (Cathartes aura) consume roughly 1,000 tons of carrion per year-providing ecosystem services valued at up to 700 million USD annually (Grilli et al. 2019). Monitoring of raptor populations, therefore, helps to understand and manage raptors and their ecosystems. ...
Examination of population trends for raptors is a research priority, especially given recent concern for their conservation status. Road counts—in which raptors are counted from a motorized vehicle moving along the ground—might be an effective method to expand the monitoring of raptor populations and estimation of trends. Here, we review past methods used to perform road counts of raptors and present revised recommendations to aid collaboration, data transfer, and interpretation of results across monitoring programs. We performed a standardized keyword search of online literature databases to obtain 148 past road count studies. The number of studies employing road counts increased per year since the 1970s. Most of these studies occurred in North America. The times of day during which road counts were conducted ranged from sunrise to sunset, and maximum speeds ranged from 10 to 113 km hr–1. The number of observers ranged from 1 (the driver) to 5. Most (93) of the studies used unlimited-width transects and fixed-width transects ranging from 0.02 to 2.50 km wide. Sixteen percent of studies calculated or corrected for the probability of detection. Such broad variation in the methodology used during road counts, coupled with infrequent correction for detection, hampers the interpretation of results across road survey programs. We suggest that road count practitioners should emphasize the collection of data, such as speed, number of observers, and distance to observed raptors, which would allow for the calculation of detection-corrected estimates. Such correction would likely improve trend estimation. Recent technology, including mobile apps, allows researchers to collect such data relatively easily, conducting their own studies while contributing to a broader raptor monitoring initiative. Road counts will likely become more useful as statistical analysis of road count data improves and researchers pool their data in a global effort to monitor raptors.
Vertebrate scavengers play a critical role in ecosystem functioning worldwide. Through the cascading effects of their ecological role, scavengers can also alleviate the burden of zoonotic diseases on people. This importance to human health fuels a growing need to understand how vertebrate scavengers and their ecosystem services are faring globally in the Anthropocene. We reviewed the conservation status of 1,376 vertebrate scavenging species and examined the implications for human health. We uncovered that 36% of these species are threatened or decreasing in population abundance and that apex (large-bodied or obligate) scavengers are disproportionately imperiled. In contrast, mesoscavengers (small-bodied or facultative) are thriving from anthropogenic food subsidies and ecological release. We posit that this global shift in scavenger community structure increases carrion persistence enabling zoonotic pathogens to propagate. Our analysis also indicates that the release of mesoscavengers is associated with reservoir host proliferation, potentially further exacerbating human disease burdens. Urgently tackling the key threats to scavengers—intensive livestock production, land use change, wildlife trade, and the interactions among them—is critical to securing the long-term public health benefits of the world’s diverse scavenger communities.
The objective of the research work was to study the “sanitary” role of necrophagous birds (Gyps fulvus, Aegypius monachus, Gypaetus barbatus, Neophron percnopterus) in the Azerbaijani part of the Lesser Caucasus. For this purpose, monitoring was conducted in the Korchay State Nature Reserve and adjacent territories in June 2013. During this period, we identified carcasses of animals that had died from various causes, including those carrying infectious diseases. In total, 28 carcasses of domestic (n=5) and wild (n=5) mammals were found. Among these, 13 carcasses were associated with six infectious diseases: rabies (five cases), toxoplasmosis (one case), brucellosis (two cases), equine adenitis (two cases), tuberculosis (one case), and canine disease (two cases). Echinococcus was identified in four animals. Notably, the number of sick animals included eight domestic and nine wild specimens. The primary causes of death for sick domestic animals were predation by mammals in pastures, old age, weakness, and hunger. Among wild animals, mortality was predominantly observed in young individuals, attributed to their inexperience and underdeveloped adaptive responses, which led them to venture into populated areas for food, making them vulnerable to hunting, traps, and transportation hazards.
In a rapidly changing world, the loss of global biodiversity presents a
significant challenge. While sustainability has become a guiding
principle for balancing the protection of the environment along with
economic development and human well-being, its implementation can
often be disjointed across various sectors. The incoherence in the
integration of environmental policies can lead to unintended negative
impacts on biodiversity, particularly for vulnerable species like vultures
and the environmental services they provide. Vultures, as a highly
threatened group of birds, are especially vulnerable to poisoning, but
also to new circular economy and renewable energy policies such as the
closure of landfills and wind energy. Thus, it is imperative to evaluate
the mechanisms and demographic responses of vulture species to these
new paradigms. My thesis examines the demography of the griffon
vulture Gyps fulvus in northeast Iberian Peninsula, using long-term data
to provide a comprehensive understanding of the population dynamics
in response to a changing environment. In Chapter 1, we studied how
the local griffon vulture population in Central Catalonia responded to
reduced organic matter in an open landfill due to European sanitary
measures aimed at closing landfills. Using the robust Schwarz and
Arnason Jolly-Seber model, we estimated the vultures' apparent survival
probability and annual abundance. We found that the available organic
matter in the landfill significantly declined after a waste treatment
centre was established, negatively impacting apparent survival. However,
local abundance remained stable, with an increase attributed to the
growth of the Catalonian breeding population. This suggests that local
waste management measures had limited impact on vultures, as their
high dispersal capacity allows them to find alternative food sources. In
Chapter 2, we used a Bayesian hierarchical Cormack-Jolly-Seber model to
analyze the age-specific demographic response of the local vulture
population at the landfill, estimating apparent survival and permanent
emigration probabilities under three scenarios of organic matter
availability: no reduction, substantial decrease, and drastic decrease. We
found a notable increase in transients among newly captured immatures
and adults. Apparent survival in juveniles declined, while in immature
residents increased and adult residents decreased. The results
suggested that intensified intraspecific competition due to reduced food
increased permanent emigration. However, resident immatures showed
resilience, indicating that high-quality individuals persisted despite food
scarcity. In Chapter 3, we used a multi-site Integrated Population Model
(ms-IPM) to examine the dynamics of griffon vulture populations in
Catalonia, Aragon, and the Valencian Community. We aimed to
understand demographic processes and inform site-specific
conservation strategies. We observed different trends: steady growth in
Catalonia, stabilization in the Valencian Community after an initial
increase, and a decline with a slight recovery in Aragon. Key growth
factors varied by region: adult survival in Aragon, floater-to-breeder
ratio and immigration in the Valencian Community, and all three factors
in Catalonia. Density dependence affected the floater-to-breeder ratio
and immigration in Catalonia and the Valencian Community, with higher
emigration to the other two sites in the vultures of Valencian
Community, likely due to nearing carrying capacity. Populations in
Aragon and the Valencian Community are stable, while Catalonia is
growing. Maintaining adult survival in Aragon is crucial, given its lower
rate and potential non-natural mortality sources. This study highlights
the value of ms-IPMs for understanding complex population dynamics
and the need for targeted conservation strategies. In conclusion, by
applying demographic models, including the ms-IPM, and addressing
data heterogeneity and uncertainty, in this thesis we gained a deeper
understanding of griffon vulture population dynamics. This approach
helped identify key demographic drivers, identify possible
environmental impacts, and inform conservation strategies, highlighting
the need for cohesive policies across regions to effectively conserve
vulnerable species like vultures.
The ecosystem services framework is essential for biodiversity conservation, emphasizing the role of nature in achieving sustainable development goals (SDGs). This study offers a global view on vulture-associated ecosystem services and their SDG contributions, based on insights from 206 experts. The findings reveal global consensus on the importance of vultures in regulation and maintenance services, such as waste recycling and disease control. Cultural services attributed to vultures are moderate and vary regionally. Provisioning services are consistently rated low across all regions. Experts’ views on vultures' key ecosystem roles are often biased toward well-known services and may not align with all scientific evidence. The study emphasizes vultures’ role in achieving SDGs, particularly impacting life on land and health, and calls for reevaluating their contribution to sustainable practices. It stresses the need to customize conservation to regional values and perceptions, recognizing vultures’ critical role in ecological balance, public health, and sustainable development.
A nonlinear dynamical model is developed in this paper that depicts interactions among vultures, human, animals and their carcasses. Diseases such as plague, anthrax and rabies are spreading due to the cascade impact caused by the catastrophic drop in the vulture population, particularly in Africa and Asia. The built model is theoretically studied using qualitative differential-equation theory to demonstrate the system’s rich dynamical features, which are critical for maintaining the ecosystem’s equilibrium. According to the qualitative findings, depending on the parameter combinations, the system not only displays stability of many equilibrium states but also experiences transcritical and Hopf bifurcations. By keeping an eye on the variables causing the decline of the vulture population, the model’s outputs may assist in maintaining balance with the prevention of the spread of disease through carcasses. Hopf-bifurcation results in the bifurcation of the limit cycle through the threshold, supporting the idea that interactions between humans and vultures may also be periodic.
Black and turkey vultures inhabit all environs of Kentucky, yet nest sites are seldom reported. In this study, 44 nest locations of black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) were recorded in north-central and south-central Kentucky, U.S.A., between 1999 and 2022. Black vultures comprised 65% of the nests found. For both species combined, 64% of the nests were in artificial structures. Artificial structures represented 82% of the black vulture nests and 31% of the turkey vulture nests. Black and turkey vulture nests averaged 481 and 987 m from human dwellings or activity. However, black vultures nested within 91 m, and turkey vultures had a nest 27 m from human activity. Abandoned houses and barns may provide a competitive advantage for black vultures over turkey vultures regarding nesting opportunities.
Raptors are powerful avian keystone species who shape the phenomenal worlds of human societies with whom they share the landscape. The material culture of Late Pleistocene and early Holocene foragers in Europe and the Eastern Mediterranean indicates that raptors attracted considerable human attention in early prehistory, yet previous work has mainly examined the role of these predatory birds as resources for food and ornamentation or the 'cognitive' implications of raptor products such as suspended talons. This chapter takes a different view and develops a comparative perspective on how such material culture participates in systems of human-raptor co-habitation, and how changing intersections and contexts of multispecies engagement precipitate a diversity of raptor-oriented practices of meaning-making. I argue that the key to understanding raptor significances in the deep past is to belabour agricentric preconceptions and to explore varying modes of human-raptor companionship in non-analogous landscapes under different human and nonhuman regimes of agency and ecosystem interaction.
Conservation of predators and scavengers should take advantage of the application of interdisciplinary approaches that connect both ecosystem processes/services and con icts/disservices. Despite this, there is an overall lack of interdisciplinary research on ecosystem processes/services and con icts/disservices provided by aerial predators and scavengers like raptors. Our speci c goals here are: i) to assess the experts' viewpoints on ecosystem processes/services and con icts/disservices provided by raptors to people and ii) to know the main intervention strategies that experts consider effective for managing raptor populations. Through an online survey we obtained 87 surveys for four raptor groups: hawks and eagles (40%), vultures (29%), owls (16%), and falcons (15%). Experts agreed that many ecosystem processes/services and only a few con icts/disservices are provided by raptors to society. Experts indicated that four ecosystem processes/services were provided by all raptor groups (i.e., vultures, falcons, hawks and eagles, and owls), and another one was provided by all the predator groups (i.e., all but vultures). In contrast, no con ict/disservice was considered to be produced by all groups of raptors. According to experts, hawks and eagles were involved in only three con icts/disservices, vultures and owls in one, and falcons in none. Experts agreed that ve strategies are effective for raptor management. Raptor conservation experts' viewpoints were mismatched with evidence from raptor literature and, as we expected, this mismatch was higher when considering con icts/disservices produced than ecosystem processes/services provided by raptors to people. To successfully promote policies and practices for raptors conservation, experts need to base their viewpoints on raptor literature.
Humans benefit from processes/services provided by predators and scavengers in ecosystems while at the same time they may suffer conflicts/disservices from them. Therefore, the conservation of predators and scavengers can benefit from applying interdisciplinary approaches that consider and connect the processes/services and conflicts/disservices that humans may receive from these animals. Although that approach has already been used quite a bit with terrestrial predators and scavengers, there is very little interdisciplinary research on flying predators and scavengers such as raptors. This thesis seeks to explore the socio-ecological factors that affect human-raptor relationships, evaluating the particular case of the Black-and-chestnut Eagle (Spizaetus isidori) throughout its distribution, in order to propose specific conservation measures.
The first specific goal (Chapter 1) was to assess viewpoints of the experts in raptor conservation about the main ecosystem processes/services and conflicts/disservices that raptors provide to humans and to know the main strategies that experts consider effective for management these species in the wild. For this, we conducted an online survey among raptor conservation experts from which we obtained 87 responses from six continents (i.e. North America, South America, Africa, Asia, Europe and Australia). We found that the viewpoints of the experts in raptor conservation around the world are biased towards the acceptance of processes/services rather than the acceptance of conflicts/disservices that raptors provide to humans. Nocturnal raptors (i.e. owls) were considered the species that provide most ecosystem processes/services (73%, 8 of 11), followed by vultures and condors (55%, 6 of 11), finally hawks and eagles and falcons (45%, 5 of 11 each one). According to experts, hawks and eagles were involved in the highest number of conflicts/disservices (37.5%, 3 of 8), vultures and condors and owls were involved in only one (12.5%, 1 de 8), respectively, while falcons were not involved in conflicts/disservices. Additionally, experts agreed on five management strategies that they believe are effective for promoting the conservation of raptors in the wild: two of these consider the participation of several social actors (i.e. bottom-up governance) and the rest are measures taken by governments (i.e. top-down governance).
The second specific goal (Chapter 2) was to assess the home range, mortality and habitat selection of the Black-and-chestnut-Eagle during natal dispersal in fragmented landscapes of tropical and subtropical Andean Montane Forests. We captured six fledglings in four nests (three in Colombia and one in Argentina) of three populations of the species, which were equipped with GPS transmitters with data download via GSM cell phone network (i.e. GPS/GSM loggers). From 20 months of age, mortality was very high (67%, 4 of 6), so we restricted the analyses to the first year of natal dispersal (i.e. between 8 and 20 months of age). We found that the home range of juveniles in the first year of natal dispersal is large (media ~996 km2; DE ± 606; rango = 294-2130 km2). During the process of natal dispersal, juveniles move through fragmented landscapes where, they consistently selected areas with a higher percentage of forest cover, higher slopes and medium altitudes with respect to availability. Although juveniles show some level of tolerance for moving through fragmented habitat, the mortality rate was very high. It is therefore suggested that in order to maintain viable populations and the key ecosystem processes/services provided by this top predator in the tropical and subtropical Andean forests of South America, we need to mitigate the causes of non-natural mortality.
The third specific goal (Chapter 3) was to examine the socio-ecological context that exacerbates the human-eagle conflict in rural communities of the eastern Andes of Colombia. We conducted 172 surveys in 20 rural communities and estimated the proportion of forest cover on each rural community (i.e. amount of remaining native forest), human density, and annual losses of domestic birds due to the Black-and-chestnut Eagle, among other socio-demographic parameters (i.e. economic activity, domestic fowl ownership, age, education, gender, etc.). We found that tolerance decreases when forest cover, human density, and annual losses of domestic birds are greater. This can make the Black-and-chestnut Eagle more vulnerable to extirpation in rural communities where forest remnants are larger. The integration of socio-ecological information allowed us to identify the rural communities with higher human-eagle conflict and thus where the conservation measures should be implemented.
The fourth specific goal (Chapter 4) was to analyze how the contributions of the Black-and-chestnut Eagle to people (perceived and real) and governance (national and local) affect the human-top predator conflict with this species in the Neotropics. The ultimate goal of governance is to manage individual behaviors and collective actions for the sustainable use of natural resources through environmental management. For this reason, this is a factor of great importance to managing human-predator conflicts. We conducted 282 surveys in rural communities around 27 nesting sites of the species in Colombia and Ecuador. We found that people's tolerance towards the eagle was negatively related to detriments (perceived and real) and disapproval of governance at the local level, but there was no influence of governance at the country level. Less than a half (40%) of interviewees disapproved of governance management at the local level. A high percentage of people showed high tolerance towards the eagle (41.13%), followed by people with a neutral position (35.46%) and finally those who indicated a low tolerance (23.41%). However, we documented human persecution of the Black-and-chestnut Eagle in most of the sampled nests (59%, 16 of 27) and in all of the assessed geographic jurisdictions. Our results suggest that systems with poor governance in other Neotropical countries, could also be negatively affecting human-predator conflicts there.
In general, each thesis chapter sought to address different socio-ecological factors that affect human-raptor relationships. These factors have historically been best known to terrestrial predators but are very little known in raptors. Therefore, the main contribution of this thesis is to provide new evidence on the importance of implementing interdisciplinary approaches to address conflicts involving raptors as the main aerial predators and scavengers in terrestrial systems. These approaches, considering the multiplicity of socio-ecological factors that interact in human-raptor relationships, increase our ability to inform decision-making and implementation of management measures, therefore, they are essential if we are to develop and implement effective conservation policies for these species in the Anthropocene.
Many apex scavenger species, including nearly all obligate scavengers, are in a state of rapid decline and there is growing evidence these declines can drastically alter ecological food webs. Our understanding of how apex scavengers regulate populations of mesoscavengers, those less‐efficient scavengers occupying mid‐trophic levels, is improving; yet, there has been no comprehensive evaluation of the evidence around the competitive release of these species by the loss of apex scavengers. Here we present current evidence that supports the mesoscavenger release hypothesis, the increase in mesoscavengers and increase in carrion in the face of declining apex scavengers. We provide two models of scavenger dynamics to demonstrate that the mesoscavenger release hypothesis is consistent with ecological theory. We further examine the ecological and human well‐being implications of apex scavenger decline, including carrion removal and disease regulation services.
Despite global conservation crises,widespread and poorly regulated toxic pesticides still cause preventable tragedies. Carbofuran, a carbamate pesticide, is the most implicated globally. In January,the latest and most shocking known poisoning incident in South America took place in Argentina, where a single Carbofuran baited sheep carcass set out by ranchers to combat mammalian predators killed 34 Andean condors (Vultur gryphus), a threatened, emblematic species of the Andes. This incident raised the number of Andean Condors poisoned in Argentina to at least 66 in the past 13 months. We must take urgent action to prevent future poisoning incidents.
Populations of the White-rumped Vulture Gyps bengalensis, Indian Vulture G. indicus and Slender-billed Vulture G. tenuirostris declined rapidly during the mid-1990s all over their ranges in the Indian subcontinent because of poisoning due to veterinary use of the non-steroidal antiinflammatory drug diclofenac. This paper reports results from the latest in a series of road transect surveys conducted across northern, central, western and north-eastern India since the early 1990s. Results from the seven comparable surveys now available were analysed to estimate recent population trends. Populations of all three species of vulture remained at a low level. The previously rapid decline of White-rumped Vulture has slowed and may have reversed since the ban on veterinary use of diclofenac in India in 2006. A few thousand of this species, possibly up to the low tens of thousands, remained in India in 2015. The population of Indian Vulture continued to decline, though probably at a much slower rate than in the 1990s. This remains the most numerous of the three species in India with about 12,000 individuals in 2015 and a confidence interval ranging from a few thousands to a few tens of thousands. The trend in the rarest species, Slenderbilled Vulture, which probably numbers not much more than 1,000 individuals in India, cannot be determined reliably.
Although there is a diversity of concerns about recent persistent declines in the abundances of many species, the implications for the associated delivery of ecosystem services to people are surprisingly poorly understood. In principle, there are a broad range of potential functional relationships between the abundance of a species or group of species and the magnitude of ecosystem-service provision. Here, we identify the forms these relationships are most likely to take. Focusing on the case of birds, we review the empirical evidence for these functional relationships, with examples of supporting, regulating, and cultural services. Positive relationships between abundance and ecosystem-service provision are the norm (although seldom linear), we found no evidence for hump-shaped relationships, and negative ones were limited to cultural services that value rarity. Given the magnitude of abundance declines among many previously common species, it is likely that there have been substantial losses of ecosystem services, providing important implications for the identification of potential tipping points in relation to defaunation resilience, biodiversity conservation, and human well-being.
Vultures provide an essential ecosystem service through removal of carrion, but globally, many populations are collapsing and several species are threatened with extinction. Widespread declines in vulture populations could increase the availability of carrion to other organisms, but the ways facultative scavengers might respond to this increase have not been thoroughly explored. We aimed to determine whether facultative scavengers increase carrion consumption in the absence of vulture competition and whether they are capable of functionally replacing vultures in the removal of carrion biomass from the landscape. We experimentally excluded 65 rabbit carcasses from vultures during daylight hours and placed an additional 65 carcasses that were accessible to vultures in forested habitat in South Carolina, USA during summer (June–August). We used motion-activated cameras to compare carrion use by facultative scavenging species between the experimental and control carcasses. Scavenging by facultative scavengers did not increase in the absence of competition with vultures. We found no difference in scavenger presence between control carcasses and those from which vultures were excluded. Eighty percent of carcasses from which vultures were excluded were not scavenged by vertebrates, compared to 5% of carcasses that were accessible to vultures. At the end of the 7-day trials, there was a 10.1-fold increase in the number of experimental carcasses that were not fully scavenged compared to controls. Facultative scavengers did not functionally replace vultures during summer in our study. This finding may have been influenced by the time of the year in which the study took place, the duration of the trials, and the spacing of carcass sites. Our results suggest that under the warm and humid conditions of our study, facultative scavengers would not compensate for loss of vultures. Carcasses would persist longer in the environment and consumption of carrion would likely shift from vertebrates to decomposers. Such changes could have substantial implications for disease transmission, nutrient cycling, and ecosystem functioning.
A major challenge today and into the future is to maintain or enhance beneficial contributions of nature to a good quality of life for all people. This is among the key motivations of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), a joint global effort by governments, academia, and civil society to assess and promote knowledge of Earth's biodiversity and ecosystems and their contribution to human societies in order to inform policy formulation. One of the more recent key elements of the IPBES conceptual framework (1) is the notion of nature's contributions to people (NCP), which builds on the ecosystem service concept popularized by the Millennium Ecosystem Assessment (MA) (2). But as we detail below, NCP as defined and put into practice in IPBES differs from earlier work in several important ways. First, the NCP approach recognizes the central and pervasive role that culture plays in defining all links between people and nature. Second, use of NCP elevates, emphasizes, and operationalizes the role of indigenous and local knowledge in understanding nature's contribution to people.
In agricultural landscapes, the Turkey Vulture Cathartes aura feeds mainly on carcases of domestic animals. In spring 2017, data on 214 flocks of Turkey vultures were collected in a road survey in Cuba (in total 2384 km). Turkey Vultures were found to be common accross Cuba, but flock size varied between habitats, reaching a maximum of 43 in valleys and 31 in agricultural landscapes with domestic animal farms. Vultures were active throughout the day, but the time of day did not significantly affect flock size. This study corroborates previous studies which suggested that carrion resources located in agricultural habitats and river valleys is crucial for the continued survival of this still abundant species. Changes in Cuba’s socio-political system in the near future will likely impact agricultural practices, and this in turn will likely affect Turkey Vultures. Our study may serve as a baseline against which future population changes and flocking behaviour of Turkey Vultures can be compared.
Animals that share resources tend to use different foraging strategies in order to decrease potential competition. Scavenging birds using the same nutritional resources can segregate into different space and time scales. However, it has been suggested that when the species do not co-evolve to achieve such segregation competition may result. Our aim was to study the trophic niche overlap between three species of obligate scavengers, the Andean Condor Vultur gryphus , Turkey Vulture Cathartes aura and American Black Vulture Coragyps atratus , which are the main avian consumers of carcasses in north-western Patagonia. Black Vultures arrived in the area relatively recently, have expanded their distribution following human activities, and have been suggested to compete with the threatened condor. We collected pellets in communal roosts of the three species to determine their diet, and to estimate the diversity (Shannon Index) and diet similarity (Pianka overlap index). We found that the Turkey Vulture has greater niche breadth and, apart from domestic livestock, it incorporates smaller items such as fish, reptiles and a great number of birds, carnivores and mice. Although the Black Vulture diet includes arthropods, they feed primarily on introduced ungulates, overlapping more with condor diet when roosting far from urban centres. As these latter two species share the same food resource, human activities that positively affect the abundance of the Black Vulture could increase competition among them, with possible implications for the conservation of the Andean Condor.
Human-wildlife conflicts currently represent one of the main conservation problems for wildlife species around the world. Vultures have serious conservation concerns, many of which are related to people's adverse perception about them due to the belief that they prey on livestock. Our aim was to assess local perception and the factors influencing people's perception of the largest scavenging bird in South America, the Andean condor. For this, we interviewed 112 people from Valle Fértil, San Juan province, a rural area of central west Argentina. Overall, people in the area mostly have an elementary education, and their most important activity is livestock rearing. The results showed that, in general, most people perceive the Andean condor as an injurious species and, in fact, some people recognize that they still kill condors. We identified two major factors that affect this perception, the education level of villagers and their relationship with livestock ranching. Our study suggests that conservation of condors and other similar scavengers depends on education programs designed to change the negative perception people have about them. Such programs should be particularly focused on ranchers since they are the ones who have the worst perception of these scavengers. We suggest that highlighting the central ecological role of scavengers and recovering their cultural value would be fundamental to reverse their persecution and their negative perception by people.
A socio-ecological approach to biodiversity conservation has recently been encouraged. We examined farmer perceptions of ecosystem services provided by scavenging vertebrates in Spain through face-to-face surveys with farmers in seven large extensive livestock systems. Scavenging services (i.e., carrion consumption) was the most perceived benefit whereas the role of some scavengers as predators was the most recognized damage. The most beneficial scavengers perceived were vultures. Overall, we detected a “Dr. Jekyll and Mr. Hyde” paradox as the same species and species within the same guild can be dually perceived as beneficial or harmful. Our findings provide evidence that traditional extensive farming linked to experience-based and local ecological knowledge drives positive perceptions of scavengers and their consideration as ecosystem services providers. Research on social perceptions can contribute to the conservation of scavengers by raising awareness about the ecosystem services provided by this functional group.
Human activities provide food resources for animals that are predictable in space and/or time. These resources, sometimes referred to as predictable anthropogenic food subsidies (PAFS), can be either the result of human-generated waste or provided intentionally, sometimes as a conservation measure. Some PAFS, including landfills, are used by common species. However, little information exists about the effects that these feeding points have on rarer species that feed there, some of which are of conservation concern. This study focuses on the influence of PAFS and their spatial location on the distribution of territories of the endangered Egyptian Vulture Neophron percnopterus. We analysed a population in the NE Iberian Peninsula that has in recent decades expanded its range. We used both null model and linear model analyses to ascertain the effect of PAFS and other covariates on the occupancy of territories by the study species. PAFS appeared to play an important role in territory selection by Egyptian Vultures, as occupied territories were nearer landfills than expected by chance. Furthermore, the distance from PAFS (landfills and vulture feeding stations, or 'restaurants') played an important role in the probability of territory occupancy by Egyptian Vultures, in addition to other environmental variables such as surface areas of rocky south-facing slopes, human settlement and the proximity of conspecifics. However, recent EU legislation aims to phase out open-air landfills to reduce the negative environmental effects of these facilities. This could have an undesired impact on the endangered species that use these feeding points. We recommend management measures that can control abundant pest species but, in the long term, other measures as supplementary feeding should be considered to counteract the probable negative effect of the disappearance of landfills on endangered species.
Effective nature conservation in human-dominated landscapes requires a deep understanding of human behaviors, perceptions and values. Human-wildlife conflicts represent relatively well-studied, global-scale conservation challenges. In Africa, vulture populations are collapsing as they fall victim to poison used by livestock farmers to kill predators, but our understanding of the prevalence of this practice is still very poor. We gathered data on the prevalence of poison use in Namibia by means of questionnaires completed by commercial farmers. The data were collected and analyzed with ad-hoc quantitative methods.We quantified prevalence of poison use, determined factors associated with this practice and derived a map of its prevalence. We found that 20% of commercial farmers in Namibia used poison; farmers that owned high numbers of small stock and on large farms, and those who had suffered high livestock losses to predators, were most likely to admit to using poison. We pinpoint areas of high prevalence of reported poison use, which are largely concentrated in the south of the country. Furthermore, we report a generally positive perception of commercial farmers towards vultures, which may indicate future potential to implement bottom-up approaches for vulture conservation. Overall, the findings have important implications for prioritizing efforts to effectively tackle the African vulture crisis and preserve healthy ecosystems for the wellbeing of humans and wildlife.
Both wing size and wing shape affect the flight abilities of birds. Intra and inter-specific studies have revealed a pattern where high aspect ratio and low wing loading favour migratory behaviour. This, however, have not been studied in soaring migrants. We assessed the relationship between the wing size and shape and the characteristics of the migratory habits of the turkey vulture (Cathartes aura), an obligate soaring migrant. We compared wing size and shape with migration strategy among three fully migratory, one partially migratory and one non-migratory (resident) population distributed across the American continent. We calculated the aspect ratio and wing loading using wing tracings to characterize the wing morphology. We used satellite-tracking data from the migratory populations to calculate distance, duration, speed and altitude during migration. Wing loading, but not aspect ratio, differed among the populations, segregating the resident population from the completely migratory ones. Unlike it has been reported in species using flapping flight during migration, the migratory flight parameters of turkey vultures were not related to the aspect ratio. By contrast, wing loading was related to most flight parameters. Birds with lower wing loading flew farther, faster, and higher during their longer journeys. Our results suggest that wing morphology in this soaring species enables lower-cost flight, through low wing-loading, and that differences in the relative sizes of wings may increase extra savings during migration. The possibility that wing shape is influenced by foraging as well as migratory flight is discussed. We conclude that flight efficiency may be improved through different morphological adaptations in birds with different flight mechanisms. This article is protected by copyright. All rights reserved.
Declines in raptor populations often result from the transformation of natural habitats to anthropogenic land uses, but the rate of population change can vary greatly among species. Declines associated with land transformation have been linked to loss of foraging habitat, prey resources and nest sites due to expanding cultivation, overgrazing and disturbance of nests and persecution by humans.
We combined extensive road‐survey counts of raptors, large‐scale GIS data sets and a single‐visit conditional likelihood N ‐mixture model to generate biome‐scale projections of abundance as a function of environmental covariates while correcting for detection error and other forms of zero inflation. This approach was employed to investigate how land‐use transformations in the threatened Cerrado savannas and Pantanal wetlands in Brazil have affected the populations of raptors on a large scale (>300 000 km ² ). We predicted that predominance of land uses with fewer or less accessible prey and scarcer nesting sites would sustain smaller raptor populations.
Twelve species were encountered sufficiently to estimate abundance, while 20 others were encountered too infrequently to permit abundance estimation. Detection of all 12 species was influenced by time of day, with variable species‐specific effects that followed expectations based on foraging and flight behaviour.
Abundance of most species was negatively influenced by conversion of natural habitats to pastures, an effect that held even for generalist species considered poor indicators of habitat quality, but was not universally impacted by urbanization and soya beans, sugarcane and Eucalyptus plantations, confirming the expectation that some species may tolerate these habitats. Spatial projections of abundance appeared realistic for most species.
Synthesis and applications . Protection of the remaining natural habitats is essential to prevent further decline of raptor populations in the Brazilian Cerrado and Pantanal, and restoration of unproductive pastures into natural habitat could prove an efficient strategy to recover diminished raptor populations. The conditional likelihood single‐visit approach is a valid and useful tool for measuring population size and for making detection‐corrected inferences of abundance over large geographical scales with sensible research budgets. Incorporating the approach into a multispecies framework would allow future studies to make important inferences for entire communities.
F ood webs developed under classical theoretical models often depict simplistic interactions among trophic levels linked by predation (Hair-ston et al. 1960). As a result, extensive research efforts have been devoted to studying predator-prey interactions, often ignoring the contribution of scavenging in food-web dynamics. However, recent advancements in food-web theory have recognized the widespread and critical role that scaveng-ing plays in stabilizing food webs in ecosystems throughout the world, thus suggesting that previous models may have greatly underestimated the importance of scavenging in food web research (Wilson and Wolkovich 2011; Barton et al. 2013). Such disregard for the importance of scavenging likely stems from a number of factors, such as human aversion to decomposing matter, difficulties in identifying scavenged versus depredated materials, and the fact that most species utilize carrion opportunistically (DeVault et al. 2003). Nonetheless, recent population declines of a number of obligate scavengers (e.g., vultures) have drawn international attention to this important group of species, and have sparked a renaissance in research on scavenging
Plastic pollution is becoming an increasing issue for wildlife throughout the world. Even remote areas with relatively little human activity are affected. The Falkland Islands are a South Atlantic archipelago with a small human population (<3000), mostly concentrated in one town, Stanley. One hundred regurgitated pellets from turkey vultures (Cathartes aura) were collected in Stanley in July and August 2015 to investigate the diet and amount of anthropogenic debris (human-made artificial products) ingested. The frequency of occurrence of anthropogenic debris was 58 % of pellets for plastic, 25 % for glass, 23 % for paper, 21 % for aluminium and 3 % for fabric. Aside from anthropogenic debris, the majority of pellets were made of sheep wool (on average 29 % of the volume), feathers (19 %) and vegetation (18 %). On average, when present, anthropogenic debris corresponded to 16.1 % of the mass of each pellet, equivalent to 1.6 g. The turkey vultures are known to feed in the open-air rubbish dump near the town. This study highlights that they ingest significant amounts of anthropogenic debris. Further investigations should be undertaken to monitor and identify potential health effects. Other birds also use the dump and may be affected. Even in such remote sparsely populated islands, pollution may be a significant issue. Rubbish management could be put in place to limit birds from feeding at the dumps. A low human population density may not indicate low pollution impacts on wildlife and the environment and should be investigated further in the Falkland Islands and at other remote islands.
Birds of prey have been, in comparison to other avian groups, an uncommon study model, mainly due to the limitations imposed by their conservative life strategy (low population density and turnover). Nonetheless, they have attracted a strong interest from the point of view of conservation biology because many populations have been close to extinction and because of their recognised role in ecosystems as top predators and scavengers and as flagship species. Today, after more than a century of persecution, and with the exception of some vultures still very much affected by illegal poisoning, many populations of birds of prey have experienced significant recoveries in many regions of Spain and the European Mediterranean. These changes pose new challenges when addressing the conservation of raptors in the coming decades. On this basis, and from a preferentially Mediterranean perspective, we have focused our attention on the need of describing and quantifying the role of these birds as providers of both regulating (rodent pest control and removal of livestock carcasses) and cultural ecosystem services. Moreover, we revisited persisting conflicts with human interests (predation of game species) and call attention to the emergence of new conflicts with a strong social and media component such as the predation on live cattle by vultures. Also, the rampant humanization of the environment determines the need for new solutions to the growing, yet scarcely explored, problem of accidents in new infrastructures such as mortality in wind farms. Finally, we explored in depth the ecological response of birds of prey to large-scale habitat changes such as urbanisation and abandonment of marginal lands that are also expected to increase in the near future. We urgently need more scientific knowledge to provide adequate responses to the challenge of keeping healthy populations of avian predators and scavengers in a rapidly changing world.
Unmanned aircraft systems (UAS) - also called unmanned aerial vehicles (UAVs) or drones - are an emerging tool that may provide a safer, more cost-effective, and quieter alternative to traditional research methods. We review examples where UAS have been used to document wildlife abundance, behavior, and habitat, and illustrate the strengths and weaknesses of this technology with two case studies. We summarize research on behavioral responses of wildlife to UAS, and discuss the need to understand how recreational and commercial applications of this technology could disturb certain species. Currently, the widespread implementation of UAS by scientists is limited by flight range, regulatory frameworks, and a lack of validation. UAS are most effective when used to examine smaller areas close to their launch sites, whereas manned aircraft are recommended for surveying greater distances. The growing demand for UAS in research and industry is driving rapid regulatory and technological progress, which in turn will make them more accessible and effective as analytical tools.
Causes of admission to rehabilitation centers can provide valuable information about factors that cause mortality in the wild. We studied causes of admission to a rehabilitation center for 108 Andean Condors (Vultur gryphus) in Chile. Seventy-nine, 28, and one condor came from central, south, and northern Chile, respectively. From central Chile, an area with high human population, the majority of condors received were adults. The most frequent causes of admission to the rehabilitation center were poisoning (52%) and collisions with power lines (13%). Seventy-two percent of the radiographed birds showed ammunition in their bodies. Almost all the condors (85%) were received during the wintering period, when condors use the lowlands, thus increasing the probability of interaction with humans. The condors admitted from southern Chile, an area with low human pressure, were mainly juveniles. The most frequently admitted birds in the south were young birds that were trapped just after fledging (68%), which made up only 4% of the cases in central Chile. There were no poisonings or collisions with power lines. Only 25% of the radiographed birds were positive for ammunition. No seasonal variation in admissions was observed, indicating that risk factors in the southern zone did not operate on a seasonal basis. The sample of birds admitted from central Chile had similar sex and age structure as the wild population, with some bias toward juveniles, in contrast with the sample from southern Chile, in which young birds dominated. In conclusion, we observed an important anthropogenic effect on causal and temporal patterns of admissions to a rehabilitation center for Andean Condors; for the segment of the population in central Chile, the mortality pressure is apparently higher than expected under natural conditions, which could promote a demographic sink in this region.
Recent increases in Black Vulture (Coragyps atratus) and Turkey Vulture (Cathartes aura) numbers, particularly in urban-suburban settings, have led to more frequent human-vulture interactions, including vulture-aircraft strikes. This problem highlights the need for vulture management strategies, including determining habitat use by these species in urban settings. We investigated the effects of structures and landscape features on habitat use by Black and Turkey vultures in and around the city of Manaus in central Amazonian Brazil. We repeatedly surveyed 80 sites (3-9 visits per site in 2009-2010) and used detection histories to derive maximum-likelihood estimates of (1) vulture occurrence and detection probabilities and (2) environmental covariate effects on occupancy. Hierarchical logistic models showed that Black Vultures were associated with urban features such as open garbage containers and streams, but Turkey Vultures were associated with forest fragments. These results suggest that Black Vultures select environments where the food supply is abundant, whereas Turkey Vultures may avoid sites that attract Black Vultures in favor of forest remnants, a habitat for which they have specific foraging adaptations. Black Vulture management should focus on reducing the amount of food waste available to the birds in urban open garbage containers and streams, but Turkey Vulture management could be improved through removal of animal carcasses, and perhaps also removal of nests and roosts from forest remnants, especially near airfields.
The California Condor (Gymnogyps californianus; hereafter “condor”; Fig. 1) has long been symbolic of avian conservation in the United States. Its large size, inquisitiveness, and association with remote places make it highly charismatic, and its decline to the brink of extinction aroused a continuing public interest in its plight. By 1982, only 22 individuals remained of this species whose range once encompassed much of North America. The last wild bird was trapped and brought into captivity in 1987, which rendered the species extinct in the wild (Snyder and Snyder 1989). In the 1980s, some questioned whether viable populations could ever again exist in the natural environment, and whether limited conservation funds should be expended on what they viewed as a hopeless cause (Pitelka 1981). Nevertheless, since that low point, a captive-breeding and release program has increased the total population by an order of magnitude, and condors fly free again in California, Arizona, Utah, and Baja California, Mexico (Fig. 2). At this writing (summer 2009), more than 350 condors exist, 180 of which are in the wild (J. Grantham pers. comm.). The free-living birds face severe challenges, however, and receive constant human assistance. The intensive management applied to the free-living populations, as well as the ongoing monitoring and captive-breeding programs, are tremendously expensive and become more so as the population grows. Thus, the program has reached a crossroads, caught between the financial and logistical pressures required to maintain an increasing number of condors in the wild and the environmental problems that preclude establishment of naturally sustainable, free-ranging populations.
Recognizing this dilemma, in November 2006, Audubon California requested that the American Ornithologists’ Union (AOU) convene an independent panel to evaluate the California Condor Recovery Program. The National Audubon Society (NAS) and the AOU have a long history of interest and involvement in condor recovery. The NAS helped fund Carl Koford’s pioneering studies of condor biology in the 1940s (Koford 1953). A previous panel jointly appointed by the NAS and AOU examined the plight of the condor in the late 1970s, and their report (Ricklefs 1978) laid the groundwork for the current conservation program. The NAS was a full partner with the U.S. Fish and Wildlife Service (USFWS) in the early days of the program, from 1980 through 1988. Ricklefs (1978) recommended that the program “be reviewed periodically by an impartial panel of scientists,” and this was done annually by an AOU committee for several years after the release of the report, but the condor program has not been formally and thoroughly reviewed since the mid-1980s. Audubon California believed that the recovery program was operating with a recovery plan (USFWS 1996) widely acknowledged to be outdated, and that issues that were impeding progress toward recovery needed outside evaluation in order for the USFWS, which administers the program, and other policy makers to make the best decisions about the direction of the program (G. Chisholm pers. comm.). Such an evaluation would also help funding organizations better invest in the program.
Turkey Vultures are one of the most widely distributed carrion feeders throughout the Americas. We analyzed their regurgitated pellets from two localities in the Atacama Desert of Chile. Natural foods included dogs, sea lions, and feathers present in 17% of the pellets. We also found that 78% of pellets from coastal sites and 83% of pellets from inland sites contained plastic material. Plastic was likely ingested because vultures scavenge in plastic bags disposed as garbage along roads and beaches. Plastic ingestion has been documented in marine birds but only occasionally in raptors. Seabirds are vulnerable to the effects of ingested plastics because of their inability to regurgitate this material. Although vultures can regurgitate plastic, we do not know the physiological effects related to ingestion of the material. The availability of food from garbage bags could partly explain the widespread distribution of these vultures in the desert, but the inclusion of these items in their diet likely provides little to no energy. Turkey Vultures patrol roads in search of animals hit by vehicles, which facilitates finding carrion and garbage. Garbage in plastic bags has increased as more roads have been built in these areas; in the future, it will be important to study the effects of ingested plastics on these birds.
Ecosystem services are those aspects of the earth that benefit humans. The Millennium Ecosystem Assessment of the United Nations identified four classes of ecosystem services: provisioning services such as food, water, timber, and fiber; regulating services that affect climate, floods, disease, wastes, and water quality; cultural services that provide recreational, aesthetic, and spiritual benefits; and supporting services such as soil formation, photosynthesis, and nutrient cycling. Interest in both the positive and negative roles of birds spurred development of Economic Ornithology, which investigated the food, habits, and migrations of birds in relation to both insects and plants. Although the discipline was initially greeted enthusiastically, criticism of methods and skepticism regarding conclusions grew in the early 20th century. Keeping in mind the eventual demise of Economic Ornithology in the early 20th century, efforts to revitalize the field today must be rigorous, repeatable, with a focus on tangible measures of plant yield in managed systems and plant fitness in natural systems. Cost-benefit analysis may permit evaluation of bird contributions to ecosystem service and disservice with respect to alternative mechanisms that are available (e.g., bird predation versus pesticides for pest control). Efforts that permit scaling up from experimental plots to entire ecosystems are critical.
Humans affect biological diversity and species distribution patterns by modifying resource availability and generating novel environments where generalist species benefit and specialist species are rare. In particular, cities create local homogenization while roads fragment habitat, although both processes can increase food availability for some species that may be able to take advantage of this new source. We studied space use by birds of prey in relation to human construction, hypothesizing that these birds would be affected even in poorly populated areas. We worked in Northwestern Patagonia, Argentina, which is experiencing a high population growth, but still having very large unpopulated areas. We related the presence of raptors with different sources of human disturbance and found that both the abundance and richness of these birds were positively associated with anthropogenic environments. These results are driven mostly by a strong association between the medium-sized generalist species and these novel environments (mainly roads and cities). This may create an imbalance in intra-guild competitive abilities, modifying the normal structures of top carnivore hierarchies. Indeed, the structure of raptor communities seems to be changing, even in poorly populated areas, with anthropogenic constructions seemingly producing changes in wild areas more promptly than thought, a cause for concern in ecosystems conservation issues.
Human–wildlife conflict is emerging as an important topic in conservation. Carnivores and birds of prey are responsible for most conflicts with livestock and game but since the mid 1990s a new conflict is emerging in south-west Europe: the presumed killing of livestock by griffon vultures Gyps fulvus. Lack of scientific data and magnification of the problem by the media are increasing alarm amongst the public, and political pressures to implement management decisions have not been based on scientific evidence. We compiled information on 1,793 complaints about attacks by griffon vultures on livestock, lodged with Spanish authorities from 1996 to 2010. Spain is home to the majority (95%) of griffon vultures and other scavengers in the European Union. Most of the cases occurred in areas of high livestock density, affected principally sheep (49%) and cows (31%), and were associated with spring birthing times (April–June). On average 69% of the complaints made annually were rejected because of a lack of evidence about whether the animal was alive before being eaten. The total economic cost of compensation was EUR 278,590 from 2004 to 2010. We discuss possible ways to mitigate this emerging human–wildlife conflict. These need to include the participation of livestock farmers, authorities, scientists and conservation groups.
Global warming due to human-induced increments in atmospheric concentrations of greenhouse gases (GHG) is one of the most debated topics among environmentalists and politicians worldwide. In this paper we assess a novel source of GHG emissions emerged following a controversial policy decision. After the outbreak of bovine spongiform encephalopathy in Europe, the sanitary regulation required that livestock carcasses were collected from farms and transformed or destroyed in authorised plants, contradicting not only the obligations of member states to conserve scavenger species but also generating unprecedented GHG emission. However, how much of this emission could be prevented in the return to traditional and natural scenario in which scavengers freely remove livestock carcasses is largely unknown. Here we show that, in Spain (home of 95% of European vultures), supplanting the natural removal of dead extensive livestock by scavengers with carcass collection and transport to intermediate and processing plants meant the emission of 77,344 metric tons of CO2 eq. to the atmosphere per year, in addition to annual payments of ca. $50 million to insurance companies. Thus, replacing the ecosystem services provided by scavengers has not only conservation costs, but also important and unnecessary environmental and economic costs.
Inference and estimates of abundance are critical for quantifying population dynamics and impacts of environmental change. Yet imperfect detection and other phenomena that cause zero inflation can induce estimation error and obscure ecological patterns.
Recent statistical advances provide an increasingly diverse array of analytical approaches for estimating population size to address these phenomena.
We examine how detection error and zero inflation in count data inform the choice of analytical method for estimating population size of unmarked individuals that are not uniquely identified. We review two established ( GLM s and distance sampling) and nine emerging methods that use N ‐mixture models (Royle–Nichols model, and basic, zero inflated, temporary emigration, beta‐binomial, generalized open‐population, spatially explicit, single visit and multispecies) to estimate abundance of unmarked populations, focusing on their requirements and how each method accounts for imperfect detection and zero inflation.
Eight of the emerging methods can account for both imperfect detection and additional variation in population size in the forms of non‐occupancy, temporary emigration, correlated detection and population dynamics.
Methods differ in sampling design requirements (e.g. count vs. detection/non‐detection data, single vs. multiple visits, covariate data), and their suitability for a particular study will depend on the characteristics of the study species, scale and objectives of the study, and financial and logistical considerations.
Most emerging methods were developed over the past decade, so their efficacy is still under study, and additional statistical advances are likely to occur.
Vultures are scavengers that fill a key ecosystem niche, in which they have evolved a remarkable tolerance to bacterial toxins in decaying meat. Here we report the first deep metagenomic analysis of the vulture microbiome. Through face and gut comparisons of 50 vultures representing two species, we demonstrate a remarkably conserved low diversity of gut microbial flora. The gut samples contained an average of 76 operational taxonomic units (OTUs) per specimen, compared with 528 OTUs on the facial skin. Clostridia and Fusobacteria, widely pathogenic to other vertebrates, dominate the vulture's gut microbiota. We reveal a likely faecal-oral-gut route for their origin. DNA of prey species detectable on facial swabs was completely degraded in the gut samples from most vultures, suggesting that the gastrointestinal tracts of vultures are extremely selective. Our findings show a strong adaption of vultures and their bacteria to their food source, exemplifying a specialized host-microbial alliance.
Livestock contributes directly to the livelihoods and food security of almost a billion people and affects the diet and health of many more. With estimated standing populations of 1.43 billion cattle, 1.87 billion sheep and goats, 0.98 billion pigs, and 19.60 billion chickens, reliable and accessible information on the distribution and abundance of livestock is needed for a many reasons. These include analyses of the social and economic aspects of the livestock sector; the environmental impacts of livestock such as the production and management of waste, greenhouse gas emissions and livestock-related land-use change; and large-scale public health and epidemiological investigations. The Gridded Livestock of the World (GLW) database, produced in 2007, provided modelled livestock densities of the world, adjusted to match official (FAOSTAT) national estimates for the reference year 2005, at a spatial resolution of 3 minutes of arc (about 5×5 km at the equator). Recent methodological improvements have significantly enhanced these distributions: more up-to date and detailed sub-national livestock statistics have been collected; a new, higher resolution set of predictor variables is used; and the analytical procedure has been revised and extended to include a more systematic assessment of model accuracy and the representation of uncertainties associated with the predictions. This paper describes the current approach in detail and presents new global distribution maps at 1 km resolution for cattle, pigs and chickens, and a partial distribution map for ducks. These digital layers are made publically available via the Livestock Geo-Wiki (http://www.livestock.geo-wiki.org), as will be the maps of other livestock types as they are produced.
Variation is key to the adaptability of species and their ability to survive changes to the Earth's climate and habitats. Plasticity in movement strategies allows a species to better track spatial dynamics of habitat quality. We describe the mechanisms that shape the movement of a long-distance migrant bird (turkey vulture, Cathartes aura) across two continents using satellite tracking coupled with remote-sensing science. Using nearly 10 years of data from 24 satellite-tracked vultures in four distinct populations, we describe an enormous amount of variation in their movement patterns. We related vulture movement to environmental conditions and found important correlations explaining how far they need to move to find food (indexed by the Normalized Difference Vegetation Index) and how fast they can move based on the prevalence of thermals and temperature. We conclude that the extensive variability in the movement ecology of turkey vultures, facilitated by their energetically efficient thermal soaring, suggests that this species is likely to do well across periods of modest climate change. The large scale and sample sizes needed for such analysis in a widespread migrant emphasizes the need for integrated and collaborative efforts to obtain tracking data and for policies, tools and open datasets to encourage such collaborations and data sharing.
Roadside raptor surveys were conducted in November 1991 along 1224 km in the northern Argentinean Patagonia. Twelve species and 477 individuals were observed. The most common species were Chimango Caracaras (Milvago chirnango) (N = 243) and Black Vultures (Coragyps atratus) (N = 72). Raptor abundance and diversity index were highest in lowland valleys and in grassy hills near the Andean cordillera. Shrubsteppe zones near other habitats had higher raptor abundance and lower diversity than inner steppe areas. The Andean woodlands had the lowest raptor abundance. We suggest that deforestation of Andean woodlands and other human-induced alterations may have had positive effects on raptor open land abundance.
In parallel with economic and social changes, mutualism in human-vulture relations has virtually disappeared worldwide. Here, we describe the mutualis-tic relationship between humans and the globally threatened Egyptian vulture in Socotra, Yemen. By analyzing both the spatial distribution of vultures and the amount of human byproducts they consume, we show that human activ-ities enable the maintenance of the densest population of this rare scavenger, whereas vultures provide a key regulating service by disposing of up to 22.4% of the organic waste annually produced in towns. Globalization is impacting the archipelago, and therefore policies that better integrate societal needs and biodiversity conservation are urgently needed. We propose a win-win solution that relies on the restructuring of the mutualism, shifting from regulating ser-vices toward cultural services. Our study highlights the necessity of reconciling trade-offs between biodiversity conservation and economic development in a framework of global change affecting Middle Eastern countries.
The Neotropics host breeding or non-breeding populations of 104 of the 109 species of New World raptors (i.e., members of the suborder Falconides and the subfamily Cathartinae), including 4 com- plete migrants, 36 partial migrants, 28 irregular or local migrants, and 36 presumed non-migrants. Stan- dardized counts of visible migration initiated in the 1990s, together with a focused literature search provide an emerging picture of raptor migration in the region. Here I describe the movements of the prin- cipal species of migrants, and detail migration geography in the Neotropics. The Mesoamerican Land Cor-
Black Vulture: The available evidence suggests that black vultures act as typical predators by seeking and disabling vulnerable animals prior to overwhelming and killing them (Gluesing et al., 1980). These birds take the path of least resistance and eat carrion when it is available. Black vultures are opportunists, however, and when the chance arises, they will attack and eat defenseless live animals. Defenseless does not necessarily mean sick or injured. Healthy newborn livestock are defenseless, especially if the mother is exhausted or otherwise not able to care for and protect the offspring. In assessing the role of black vultures as livestock predators, it is difficult to obtain objective, unbiased information because direct observations of black vulture attacks on livestock are uncommon. Usually, the investigator arrives at the feeding site after the prey animal is dead and the chain of events leading to the demise of the animal is speculative. The fact that black vultures are feeding on a carcass is not evidence that the birds killed the animal. Some animals are stillborn and others die for reasons unrelated to black vultures. Female livestock, especially young and inexperienced ones, sometimes suffer mortal injuries while giving birth. If vultures attack and kill such mortally injured animals, they are eliminating individuals that are already doomed. As the black vulture population increases and its range continues to expand, depredations to livestock are likely to increase. To resolve these conflicts, research is needed to understand more fully the population dynamics of this species and to determine factors that contribute to the birds’ preying on livestock. In particular, it will be important to know why some livestock operations incur vulture damage while other ranches are not affected. Research is currently underway specifically to address these data gaps. Golden Eagle: Golden eagle populations are increasing in western states with sheep production. It is unknown whether increased eagle numbers translates into increases in livestock depredations. It is important for livestock producers to understand that management techniques for golden eagles are limited. The combination of human-like scarecrows, harassment and increased human activity is the most feasible means of protecting lambing bands from golden eagles. As potential new avian management techniques evolve, an effort should be made to evaluate their effectiveness to reduce livestock depredation from golden eagles.
Assessing the non-market value of biodiversity conservation is crucial to justify it economically. Using a choice experiment on wetland restoration in Hokkaido, northern Japan, we assessed the willingness of citizens to pay for different ecological statuses of a flagship species (absence, occasional occupancy, permanent occupancy, and breeding) and other principal conservation targets (establishment of a birdwatching station and wetland sizes). The results showed that the fundraising potential of the flagship species surpassed those of other conservation targets, irrespective of its ecological status, highlighting the superior publicity generated by charismatic species. We also showed that upgrading ecological status from occupancy to breeding did not result in additional financial support. Our study emphasizes that, although publicizing ecologically important statuses such as breeding is critical for successful conservation efforts, focusing much effort on flagship species rather than other conservation targets may be important to increase the economic value of conservation practices if such species are available.
This cutting-edge title is one of the first devoted entirely to the issue of carbofuran and wildlife mortality. It features a compilation of international contributions from policy-makers, researchers, conservationists and forensic practitioners and provides a summary of the history and mode of action of carbofuran, and its current global use. It covers wildlife mortality stemming from legal and illegal uses to this point, outlines wildlife rehabilitation, forensic and conservation approaches, and discuss global trends in responding to the wildlife mortality. The subject of carbofuran is very timely because of recent parallel discussions to withdraw and reinstate the insecticide in different parts of the world. Incidences of intentional and unintentional wildlife poisonings using carbofuran are undeniably on the rise, especially in Africa and India and gatherings of stakeholders are being organized and convened on a global basis. There is still a need to consolidate information on the different experiences and approaches taken by stakeholders. Carbofuran and Wildlife Poisoning is a comprehensive overview of global wildlife mortality, forensic developments and monitoring techniques and is a definitive reference on the subject. It comprises of historical and current perspectives, contributions from key stakeholders in the issue of global wildlife poisonings with carbofuran, people on the ground who deal with the immediate and long-term ramifications to wildlife, those who have proposed or are working towards mitigative measures and solutions, those in contact with intentional or unintentional 'offenders', those who have adapted and developed forensic methodology and are gathering evidence. "Carbofuran and Wildlife Poisoning is a collection of meticulously researched papers from all around the world that provide shocking facts about the effects of a deadly insecticide on wildlife. The book discusses the hundreds of thousands of animals, from elephants to fish, that are poisoned each year, the efforts to rehabilitate those which have been rescued, and the often heroic efforts to ban or reduce the use of the deadly chemical. This book is a must for all those concerned with the problem." -Jane Goodall, PhD, DBE, Founder - the Jane Goodall Institute & UN Messenger of Peace, October 2011.
Vultures, which are the only obligate vertebrate scavengers, have experienced the most rapid decline in conservation status of any group of birds over the past decade and comprise the most threatened avian functional guild in the world. Of the 22 vulture species, nine are critically endangered, three are endangered, four are near threatened, and six are least concern. Meanwhile, the vast majority of avian facultative scavenger species, such as corvids and gulls, have stable or increasing populations. We analyze the causes of this stark contrast in status and evaluate what ecological factors contribute to extinction risk for all 106 avian scavenger species. A random forest model shows that diet breadth, proportion scavenged diet, geographic realm, body mass, clutch size and taxonomy are leading predictors of extinction risk. Meanwhile, dietary toxins – most notably poisons and the veterinary drug diclofenac – are by far the most important anthropogenic threat to avian scavengers, comprising the leading cause of decline for 59% of threatened avian scavenger species and 88% of threatened vulture species. Currently, 73% of vulture species are extinction-prone (near threatened, vulnerable, endangered, critically endangered and extinct) and 77% have declining populations, while only 13% of avian facultative scavenger species are extinction-prone and 70% have stable or increasing populations. As vultures decline, populations of many facultative scavengers are growing, causing trophic cascades from increased predation, competition, and invasion. Furthermore, vultures' highly specialized digestive systems efficiently eradicate diseases when consuming carrion, whereas facultative scavengers are more susceptible to contract and transmit diseases among themselves and to humans. We urge immediate action, particularly by regulating lethal dietary toxins, to prevent the extinction of vultures and loss of respective ecosystem services.
Damage by black (Coragyps atratus) and turkey (Catharates aura) vultures increased annually since 1990, when 2 complaints were reported, and peaked at 207 complaints in 1995. Black vultures are associated with depredations of livestock and pets and damage to real and personal property. Congregations of mixed flocks of black and turkey vultures are associated with health concerns, property damage, and nuisance complaints. Turkey vultures are infrequently identified as a problem compared to black vultures and mixed flocks. Vulture damage was reported in 55 counties and 2 cities in Virginia from October 1994 to 1996. Black vultures were reported to kill cattle or calves in 32 counties, with 76% of statewide livestock predation reported from Southwestern Ridge and Valley and Southern Piedmont physiographic regions. Eleven counties reported black vultures killing other livestock, including farm-raised deer. Twelve counties reported black vultures killing, injuring, and harassing pets. While there is a range of nonlethal techniques to alleviate black vulture predation on livestock - including harassment with pyrotechnics or center-fire rifles, removing carrion, moving expectant cattle to alternate pastures, relocating nearby vulture roosts by harassment with pyrotechnics, and monitoring livestock several times a day - these techniques frequently were ineffective. The lethal method recommended to reduce or stop black vulture predation on livestock was shooting a few vultures to supplement harassment. New research is needed to develop control methods to alleviate vulture damage and develop vulture population models.
Birds are conspicuous, ubiquitous, and arguably the best studied group of vertebrates on the planet. Birds are also observed by millions of passionate birdwatchers worldwide. Birds engage in numerous and important ecosystem functions. Birds plant forests, devour pests, pollinate flowers, and scavenge carrion. Investigation of these ecosystem functions directly as ecosystem services has grown immensely over the last two decades. The services provided by birds are crucial to understand their importance for ecosystems and for the people that benefit from them. The chapters in this volume describe in detail many of the ecosystem services provided by birds. The examples throughout this book suggest that birds’ ecological roles, and, therefore, ecosystem services are critical to the health of many ecosystems and to human well-being. With understanding and valuing bird services we may assess the environmental consequences of bird declines and extinctions and communicate these findings to the public and policy makers. Thus we may support the conservation of birds and their habitats.
http://press.uchicago.edu/ucp/books/book/chicago/W/bo23996771.html
A series of baits was used to study the scavenging efficiency of Turkey Vultures (Cathartes aura) in tropical forest. These birds were found to rely almost entirely on their sense of smell to locate food. They could not easily find animals that had died recently, were efficient at locating one-day-old carcasses, and tended to reject meat that was rotten. Estimates of the amount of food taken from the baits showed that Turkey and Black vultures removed about 90% of the provided food supply.
We investigated spatial and temporal differences in the habitat associations of five New World vulture taxa (family Vulturidae auct. Cathartidae) in the Llanos of central Venezuela. Overall numbers of vultures were higher over open or semi-open savanna habitats than closed canopy riverine gallery forest. Black Vultures Coragyps atratus brasiliensis and Lesser Yellow-headed Vultures Cathartes burrovianus foraged principally in open habitats at all times. Although King Vultures Sarcoramphus papa were counted mainly over gallery forest they also sometimes foraged outside the forest area. During the wet season, resident Turkey Vultures Cathartes aura ruficollis foraged in all habitats but highest densities occurred over gallery forest, east of the main highway. This indicated that, to some extent, vulture species were ecologically segregated by habitat. During the dry season, a larger, dominant, migratory race of Turkey Vulture, C. a. meridionalis, coexisted with the resident subspecies. Migrants foraged at highest densities over open and semi-open habitats, but they also occurred in low numbers over gallery forest. When sympatric with these migrants, resident Turkey Vultures foraged almost exclusively in closed gallery and semi-deciduous tropical forest to the east of the highway, and, in contrast to the wet season, avoided open habitats. At the end of the dry season (March to April), migrant Turkey Vultures departed for North America to breed, resulting in a dramatic reduction in densities of Cathartes vultures. Despite the absence of migrants, densities of Cathartes vultures remained higher in open and semi-open savanna habitats than the gallery forest area. Support for a possible niche shift came from the proportion of carcasses visited in different habitats by resident Turkey Vultures, habitat sightings of wing-tagged birds and radiotracking studies.
In parallel with economic and social changes, mutualism in human-vulture relations has virtually disappeared worldwide. Here, we describe the mutualistic relationship between humans and the globally threatened Egyptian vulture in Socotra, Yemen. By analyzing both the spatial distribution of vultures and the amount of human byproducts they consume, we show that human activities enable the maintenance of the densest population of this rare scavenger, whereas vultures provide a key regulating service by disposing of up to 22.4% of the organic waste annually produced in towns. Globalization is impacting the archipelago, and therefore policies that better integrate societal needs and biodiversity conservation are urgently needed. We propose a win-win solution that relies on the restructuring of the mutualism, shifting from regulating services toward cultural services. Our study highlights the necessity of reconciling trade-offs between biodiversity conservation and economic development in a framework of global change affecting Middle Eastern countries.