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Birds of Prey in Agricultural Landscapes: The Role of Agriculture Expansion and Intensification

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Abstract

The introduction of agricultural activity (including livestock farming) in natural environments affects all the natural processes occurring there, from individual behavior and population dynamics to communities’ composition and flows of matter and energy, and from local to landscape scales.

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... The importance of these threats to birds and other wildlife globally has also been highlighted by previous reviews (BirdLife International, 2013;Joppa et al., 2016;Tilman et al., 2017). With some notable exceptions (Buij et al., 2013;Murgatroyd et al., 2016;Grande et al., 2018), raptors tend to be victims of global expansion of agriculture and logging (Foley et al., 2011;Laurance et al., 2014;Grande et al., 2018). 'Ecosystem Conversion and Degradation' is listed as a Medium or High impact stress for 2.6 times as many raptor species than 'Species Mortality,' although threats causing mortality can have acute effects on raptor populations (e.g., Buechley and Şekercioğlu, 2016;Oaks et al., 2004;Ogada et al., 2016). ...
... The importance of these threats to birds and other wildlife globally has also been highlighted by previous reviews (BirdLife International, 2013;Joppa et al., 2016;Tilman et al., 2017). With some notable exceptions (Buij et al., 2013;Murgatroyd et al., 2016;Grande et al., 2018), raptors tend to be victims of global expansion of agriculture and logging (Foley et al., 2011;Laurance et al., 2014;Grande et al., 2018). 'Ecosystem Conversion and Degradation' is listed as a Medium or High impact stress for 2.6 times as many raptor species than 'Species Mortality,' although threats causing mortality can have acute effects on raptor populations (e.g., Buechley and Şekercioğlu, 2016;Oaks et al., 2004;Ogada et al., 2016). ...
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Raptors provide critical ecosystem services, yet there is currently no systematic, global synthesis of their conservation status or threats. We review the International Union for the Conservation of Nature's Red List to examine the conservation status, distributions, threats, and conservation recommendations for all 557 raptor species. We further assess the significance of Important Bird and Biodiversity Areas (IBAs) for raptor conservation. We also determine which countries contain the most species listed under the Memorandum of Understanding on the Conservation of Migratory Birds of Prey in Africa and Eurasia (Raptors MoU). Raptors, especially Old World vultures, are more threatened than birds in general. Eighteen percent of raptors are threatened with extinction and 52% of raptors have declining global populations. South and Southeast Asia have the highest richness and the largest number of threatened raptor species. By country, Indonesia has the highest richness of raptor species (119) and most declining species (63). China and Russia contain the most Raptors MoU species, although they are not yet signatories to the agreement. Raptor species that require forest are more likely to be threatened and declining than those that do not. Agriculture and logging are the most frequently identified threats, although poisoning is especially detrimental to Old World vultures. Of the 10 most important IBAs for raptors, six are in Nepal. Highest priority conservation actions to protect raptors include preventing mortality and conserving key sites and priority habitats. Improved long-term monitoring would allow for conservation to be appropriately targeted and effectiveness of interventions to be assessed.
... Land use intensification creates regions that may include a continuum of environmental conditions (Marzluff et al. 2001) from "wildlands" to rural, suburban and urban environments (Chapman & Reiche 2007), in which native vegetation is displaced and the species richness of wildlife is reduced (Cam et al. 2000;Fraterrigo and Wiens 2005). Urbanization affects species diversity and the composition of avian communities in natural areas surrounding urbanized zones (Chace and Walsh Grande et al. 2018, Kettel et al. 2018, Mak et al. 2021. ...
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Raptor conservation programs should be based on knowledge of the birds’ ecology in both natural and urban habitats, justifying the inclusion of ecological studies in suburban zones into regional planning initiatives. The objective of this study was to determine the use of diurnal raptors within the habitats of a suburban area of a city in southern Chile. We characterize the different zones into five types of environment, and assess their raptor diversity for consideration in territorial planning. Acoustic surveys were conducted in auditory stations in addition to observations from fixed transects and trails. From a total of 161.39 h of survey, we obtained 664 sightings corresponding to ten species of diurnal raptors. The richest environment was dense forest (eight species), followed by grassland (six species), native forest regeneration (five species), shrubs (four species) and exotic tree plantations (three species). We discuss the relationship between the richness of diurnal raptors, the types of environment in the study area, and the spatial location of the sites, as well as the implications for territorial planning to support the conservation of birds of prey in the suburban zone studied.
... Changes also embrace the alteration of crop species composition (e.g. the growing popularity of oilseed rape Brassica napus) (Panek and Hušek 2014). These changes in farmland habitats throughout the EU began to threaten birds living or foraging in these sites (BirdLife International 2004, Mirski 2009, Grande et al. 2018, including bird species like the Lesser Kestrel Falco naumani (Donázar et al. 1993), Little Owl Athene noctua (Šálek and Schröpfer 2008) and predicted for the Montagu's Harrier Circus pygargus and references therein). Lithuania accessed the EU in 2004; between 1990 and 2010, its arable lands increased by 27.7%, but at the same time, its grasslands and natural pastures declined by 59.4%. ...
Article
Environmental changes are expected in Europe due to ongoing timber harvesting in forests and changes in agriculture practices in cultivated areas. This study aimed to determine whether the nest site characteristics of the Common Buzzard Buteo buteo – a generalist raptor – have changed over time due to ongoing changes in forests and agricultural areas that are highly important for its breeding. A comparison of Common Buzzard nest sites occupied in 2002–2004 with nest sites occupied in 2017–2018 in commercially managed forests indicated certain changes. Common Buzzards preferred to nest in more mature stands with the higher proportion of deciduous trees in composition of the first tree layer. The location of stands in regard to agricultural areas did not shape habitat choice. The oak was most important nests tree. The nest sites of the Common Buzzard remained similar in terms of location within the landscape, however, age of stands used for nest significantly increased. In summary, these results suggest that Common Buzzard nest site selection pattern was driven by stand level decisions, but were not shaped by the landscape features. These findings indicate that behavioural plasticity typically assumed for this ubiquitous raptor may not necessarily act at the all levels of nest site selection process, which may further indicate species potential sensitivity to the changes in forest utilisation intensity. Keywords: habitat selection, raptor, forestry impact
... Where human populations were studied to better understand behavior and belief and value systems, residents and farmers (which we acknowledge are not the most descriptive categories) were the populations most frequently studied. We found this focus to be logical, since a focus on residents in an area with prevalent raptor persecution is important to understanding that persecution, and agriculture is the most common threat identified for global raptor populations [35,36]. However, we note an overfocus on general and broadly defined behavioral or sociocultural concepts such as attitudes and values-which is also a trend among general human dimensions of conservation research [37]-as opposed to other concepts that may be closer antecedents to behavior, such as experience, intentions, mortality, risk perception, and emotions. ...
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Global raptor conservation relies on humans to establish and improve interaction and coexistence. Human–wildlife interaction research is well-established, but tends to focus on large-bodied, terrestrial mammals. The scope and characteristics of research that explores human–raptor interactions are relatively unknown. As an initial step toward quantifying and characterizing the state of applied, cross-disciplinary literature on human–raptor interactions, we use established systematic map (scoping reviews) protocols to catalog literature and describe trends, identify gaps and biases, and critically reflect on the scope of research. We focus on the peer-reviewed (refereed) literature germane to human–raptor interaction, conflict, tolerance, acceptance, persecution and coexistence. Based on 383 papers retrieved that fit our criteria, we identified trends, biases, and gaps. These include a majority of research taking place within North America and Europe; disproportionately few interdisciplinary and social research studies; interactions focused on indirect anthropogenic mortality; and vague calls for human behavior changes, with few concrete steps suggested, when management objectives are discussed. Overall, we note a predominant focus on the study of ecological effects from human–raptor interactions rather than sociocultural causes, and suggest (as others have in various conservation contexts) the imperative of human behavioral, cultural, and political inquiry to conserve raptor species.
... Where human populations were studied to better understand behavior and belief and value systems, residents and farmers (which we acknowledge are not the most descriptive categories) were the populations most frequently studied. We found this focus to be logical, since a focus on residents in an area with prevalent raptor persecution is important to understanding that persecution, and agriculture is the most common threat identified for global raptor populations [35,36]. However, we note an overfocus on general and broadly defined behavioral or sociocultural concepts such as attitudes and values-which is also a trend among general human dimensions of conservation research [37]-as opposed to other concepts that may be closer antecedents to behavior, such as experience, intentions, mortality, risk perception, and emotions. ...
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Global raptor conservation relies on humans to establish and improve interaction and coexistence with raptor species. Human-wildlife interaction research is well-established, but tends to focus on large-bodied, terrestrial mammals. The scope and characteristics of research that explores human-raptor interactions is relatively unknown. As an initial step toward quantifying and characterizing the state of applied, cross-disciplinary literature in human-raptor interactions, we use established systematic map protocols to catalog the literature and describe trends, identify gaps and biases, and critically reflect on the state of the literature. We focus on peer-reviewed literature germane to human-raptor interaction, conflict, tolerance, acceptance, and coexistence. Based on the 383 papers retrieved from the literature that fit our criteria, we identified trends, biases, and gaps. These include a majority of research taking place within North America and Europe; disproportionately few interdisciplinary and social research studies; interactions focused on indirect anthropogenic mortality (poisons and wind turbine collisions); and vague calls for human behavior changes, with few concrete steps suggested, when management objectives are discussed. Overall, we note a predominant focus on the study of ecological effects from human-raptor interactions rather than sociocultural causes and suggest (as others have in various conservation contexts) the imperative of human behavioral, cultural, and political inquiry to conserve raptor species.
... Birds, including raptors, are highly influenced by human-induced landscape alterations as they are sensitive to environmental changes (Cooper et al. 2021;McCabe, 2018). Prey diversity and habitat heterogeneity among other factors play an important role in the distribution, status, and diversity of raptors in an ecosystem (Grande et al. 2018;Sanchez-zapata and Colvo, 1999). Urban and suburban landscapes act as suitable habitats for raptors by providing their key requirements such as food resources, nesting habitats, and breeding grounds (Natsukawa, 2021;Palomino and Carrascal, 2007;Chettri et al. 2005). ...
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Despite their significance in food webs, little is known about the spatial ecology of raptors in urban areas and their habitat use in wetland-associated habitats is scarcely investigated. This research aimed to study the distribution of raptors and habitat use in a wetland that is under anthropogenic influence. Occurrence, diversity, and habitat use of raptors were investigated in three different habitat types: vegetated, edge, and open water. Nine raptor species representing nearly 33% of all raptors in Sri Lanka were found to be inhabiting the wetland where the family Accipitridae had the highest diversity. Edge habitats supported the highest species diversity. This study serves both to highlight the importance of urban wetlands as a home for raptors and to emphasize the contribution of anthropogenic habitat alterations toward increased raptor diversity in edge habitats.
... Birds of prey are top predators and a key part of ecosystems, as they modulate through cascading effects lower trophic levels, thus structuring prey communities and affecting positively biodiversity (Duffy 2002). Moreover, given their low natural abundances and their large spatial requirements, birds of prey have shown they can be particularly sensitive to large changes in ecosystems, such as those produced by agricultural expansion and intensification (Sergio et al. 2005, Grande et al. 2018. The replacement of natural habitats by crops and the intensification of agricultural practices in areas already farmed traditionally can completely alter food availability for raptors, affecting raptors foraging by eliminating the ecological niches for some of their prey, by the decrease in the carrying capacity of the environment for the prey species that remain (Cardador et al. 2012) or by altering the possibility of raptors to access these prey, for example by changes in vegetation structure (Preston 1990, Rodríguez et al. 2014. ...
... Habitat destruction and alteration via agricultural expansion and logging is the most prominent cause of declining population of raptors (Bildstein 2006;Goriup and Tucker 2007;McClure et al. 2018;Grande et al. 2018). It was observed during the survey that the lower reaches of the Proc Zool Soc study area have sizeable agricultural activity and human habitations than the upper reaches. ...
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Raptors are high in trophic level and play an essential role in the functioning of an ecosystem, yet not much information about their distribution and abundance is available from the Indian Himalayan region. The present study was conducted in the Indian part of the Kailash sacred landscape, Western Himalayas, between February 2015–December 2017, documenting the distribution and abundance status of raptors in the landscape. Altogether, 320 km of trails were walked, and 1162 km of the vehicular survey were conducted through different habitats. A total of 506 individuals of 25 species belonging to three families were recorded. Nine Globally Threatened/Near Threatened species and eight migrant species were observed from the landscape. Himalayan vulture Gyps himalayensis was the most abundant and widely distributed raptor, followed by Black-eared kite Milvus migrans lineatus and Steppe eagle Aquila nipalensis. The population of raptors is declining worldwide, and in the Kailash landscape, this lesser-known group should be monitored regularly and protected by ensuring the availability of suitable and undisturbed habitat, control on forest fire, and uncontaminated food.
... Álvarez et al. (1996) also reported the killing of Collared Forest-Falcons that prey on domestic poultry in humanmodified rainforests of Venezuela. Increased percent of open or disturbed habitats in territories of Collared Forest-Falcons in low forest-cover landscapes may increase their risk of mortality from other anthropogenic causes such as collision with power lines, fences, and human-made structures (Bird et al. 1996, Grande et al. 2018. This is of particular concern given that forest-dependent raptor species are at greater conservation risk than other species, where agriculture expansion and forest loss are the main threats for conservation of these raptors (McClure et al. 2018). ...
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The availability of habitat determines patterns of habitat use and selection by raptors, and habitat loss in human-modified landscapes may influence habitat use by individual raptors. This is important for tropical forest-dependent species, which face an accelerated rate of habitat loss worldwide. I evaluated habitat use and selection by Collared Forest-Falcons (Micrastur semitorquatus) in the fragmented rainforest of the Los Tuxtlas Biosphere Reserve, state of Veracruz, Mexico. I conducted vantage point and transect observations combined with playbacks to survey Collared Forest-Falcons in March–June 2012 and 2013. I estimated habitat use and selection by forest falcons that inhabit low forest-cover and high forest-cover landscapes. In general, Collared Forest-Falcons selected primary forest and included higher proportions of this habitat within their territories and core areas. Even though the falcons avoided cattle pastures, individuals inhabiting low forest-cover landscapes included a higher proportion of this land cover within their territories, probably as a response to low forest availability in the landscape. Results from this study demonstrate that Collared Forest-Falcons preferentially selected primary rain forests but also used secondary forests in Los Tuxtlas Biosphere Reserve. Low forest-cover in the landscape may be influencing habitat use patterns of falcons, forcing them to use a higher amount of the suboptimal habitat, and increasing their risk of mortality with potential consequences for population dynamics.
... Álvarez et al. (1996) also reported the killing of Collared Forest-Falcons that prey on domestic poultry in humanmodified rainforests of Venezuela. Increased percent of open or disturbed habitats in territories of Collared Forest-Falcons in low forest-cover landscapes may increase their risk of mortality from other anthropogenic causes such as collision with power lines, fences, and human-made structures (Bird et al. 1996, Grande et al. 2018. This is of particular concern given that forest-dependent raptor species are at greater conservation risk than other species, where agriculture expansion and forest loss are the main threats for conservation of these raptors (McClure et al. 2018). ...
... In agroecosystems, raptor distributions are influenced by the availability of perches and prey abundance, with raptor abundances typically declining as agriculture becomes more intensive (Boano and Toffoli 2002, Filloy and Bellocq 2007, Butet et al. 2010, Grande et al. 2018. Although artificial nest boxes and perches can improve raptor habitat quality in agricultural landscapes (Fargallo et al. 2009, Paz et al. 2012, Shave and Lindell 2017, artificial perches are not commonly available and there is no organized network of nest boxes in our study area (Zagorski and Swihart 2020). ...
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The populations of many species of raptors that forage in agroecosystems have declined as agriculture has intensified. Cover crops are a recent trend in areas of intensive row-crop agriculture in the Midwestern United States that could positively affect raptors by increasing the abundance and distribution of raptor prey. We assessed the habitat use of two raptors, American Kestrel (Falco sparverius) and Red-tailed Hawk (Buteo jamaicensis), and tested for use of areas near cover-cropped fields. We conducted 1184 km of roadside transects in 2018 and 2019 in west-central Indiana and recorded 191 detections of our focal species. We constructed resource selection functions within a use-availability design to evaluate raptor habitat use with a series of weighted logistic regression models. For each species, we fitted models at two scales (transect and landscape) and with two definitions of available points (completely random and random subject to perch constraints). American Kestrels were strongly associated with cover-cropped agricultural fields. Red-tailed Hawks were strongly associated with woodlots. Scale did not greatly affect the inclusion of habitat variables into top models for either species. Random models identified potential perch sites, whereas constrained random models identified more subtle habitat preferences not included in the random models. For American Kestrels, constrained models revealed reduced use of woodland perches and increased use of perches near cover-cropped and conventional agricultural fields. For Red-tailed Hawks, constrained models revealed habitat associations, particularly reduced use of utility lines and human development, that were absent or de-emphasized in random models. Modeling resource selection with constrained random availability will work best for well-studied species with discrete, easily mapped habitat features. If damage to commodity crops by rodents in cover-cropped fields is a concern, raptor management should focus on kestrels and could include erection of artificial perches, nest boxes, and enhancement of permanent herbaceous habitats for hunting.
... In order to make effective decisions on future raptor conservation efforts, and to optimize the use of the limited economic resources, a more comprehensive knowledge of the socio-ecological contexts in which these human-raptor conflicts occur is necessary. As in the case of the BC Eagle populations, other forest raptor species of the Neotropical region are declining primarily due to an increase in HWC (Barbar et al., 2016;Gusmão et al., 2016;Muñiz-López, 2017;Restrepo-Cardona et al., 2020;Sarasola and Maceda, 2006) associated with processes of habitat loss and fragmentation due to agriculture expansion (Grande et al., 2018a;McClure et al., 2018). The mechanisms by which habitat loss and fragmentation, and human persecution in the context of Box 1: Socio-ecological system approach applied to human-wildlife conflicts, adapted from Carter et al. ...
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Fragmentation of the world's most intact forest landscapes will likely increase the severity of Human Wildlife Conflict (HWC). The way these threats affect top predators involves a series of complex social and ecological relationships, which are not completely understood, and thus require socio-ecological studies. The aim of this study is to examine the socio-ecological factors that affect the tolerance of local people towards the endangered Black-and-chestnut Eagle (Spizaetus isidori) in rural villages of the eastern Andes of Colombia. We conducted 172 interviews in 20 rural villages and estimated the proportion of forest cover (i.e. amount of remaining native forest), human density, the yearly losses of domestic fowl by the Black-and-chestnut Eagle, and socio-demographic parameters (i.e. economic activity, domestic fowl ownership, age, education, gender). The likelihood of villagers being tolerant towards the Black-and-chestnut Eagle decreased when the forest cover, human density and yearly losses of domestic fowl were higher. The integration of socio-ecological information allowed us to identify key areas with increasing HWC. Our findings were in consonance with the most recent evidence indicating that declines of top predator populations, as well as other vertebrate biodiversity, can be severely affected by the exacerbation of HWC on the border of intact native habitat and deforested areas.
Thesis
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DETERMINING AND MONITORİNG OF THE CINEREOUS VULTURE POPULATİON İN THE KÖROĞLU MOUNTAINS FOREST MSC THESIS ŞAFAK ARSLAN BOLU ABANT İZZET BAYSAL UNIVERSITY INSTITUTE OF THE GRADUATE STUDIES WILDLIFE ECOLOGY AND MANAGEMENT (SUPERVISOR: DOÇ.DR. CİHANGİR KİRAZLI) BOLU, AUGUST 2020 Cinereous vulture Aegypius monachus L. is a primary scavenger with a decreasing global population categorized as Near Threatened (NT). It is a species of conservation priority; therefore, the determination of new nesting areas, nesting and reproducing area preferences, reproduction success rates and the threats against the species is of utmost importance in order to ascertain the connection points of the Cinereous Vulture populations and to conserve the species. To that end, 37 field studies were conducted regarding the species in 2018 and 2019 in the Köroğlu Mountains, which set the border between the Central Western Black Sea and the Central Anatolia regions. The aims of these field studies were set as determining the new nesting areas and monitoring the breeding success, determining the nest and nest site preferences and the threats against the species. In the Koroglu Mountains, 83 nests belonging to the species were found, and it was seen that 39 pairs had shown breeding activity in 2018, while in 2019 it was 60 pairs. Their breeding success were 67% and 73%, respectively. Analyses have shown that the Cinereous vulture prefers old and tall black pine trees as nesting trees, and that it uses the degraded stands and the high oblique areas facing the South-Southeast direction in the 1345-1716 m elevation range (black pine zone) for nesting. The biggest cinereous vulture colony in Turkey was discovered during this field study conducted in Köroğlu Mountains. Minimum limit of the black vulture population with this field study in Turkey has been updated with 194 pairs. It was seen that the cutting of potential nesting trees and road construction in forests as part of forestry activities are the most critical threats against the species. KEYWORDS: Cinereous Vulture, Köroğlu Mountains, Nest Site Selection, Nest Tree Selection, Breeding Success, Threats, Population
Thesis
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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.
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Raptors are highly sensitive to environmental and human-induced changes. In addition, several species of raptors exist in considerably small numbers. It is thus critical to conserve raptors and their habitats across relatively larger landscapes. We examined the diurnal raptor assemblages and seasonality in a subtropical habitat in India’s northwestern Himalayas. Quantitative data on diurnal birds of prey and their habitat features across six distinct habitat types were collected from 33 sample sites. We observed 3,434 individuals of 28 diurnal raptors belonging to two orders and three families during a two-year survey from December 2016 to November 2018. A significant variation in bird species richness and abundance was found across habitats and seasons, with farmlands and winters being the most diverse and speciose. The generalized linear model, used to determine raptor community responses, indicated that elevation and proximity to dumping sites significantly affected the raptor abundance. The non-metric multidimensional scaling (NMDS) revealed significant differences in raptor assemblages across the habitat types. The study concluded that raptors’ persistence is largely determined by their preference for favourable feeding, roosting, and nesting opportunities. The presence of protected and habitat-exclusive species validates the high conservation importance of these ecosystems, particularly the forest patches and farmlands, necessitating robust conservation and management measures in this part of northwestern Himalaya.
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The Chaco Eagle (Buteogallus coronatus) is a globally “Endangered” raptor with little known about its biology. In this work, we provide data on the reproductive biology of the Chaco Eagle collected between 2007 and 2018 with the discovery of nine nests in five areas of the state of Minas Gerais, Brazil. Clutch size is one egg (n = 6 nests) with incubation occurring between August and November and fledging between January and February. The species showed plasticity in the characteristics of the occupied trees and nesting sites, nesting in both conserved and disturbed areas. Monitoring of some pairs indicated a reproductive reproduction event every 2 to 3 years. Only 33% of the observed breeding attempts generated successful fledglings. Most of the 20 dietary items collected were reptiles and armadillos. Despite presenting environmental plasticity, data from this study suggest low reproductive success for the Chaco Eagle and thus reinforce the importance of long-term monitoring of reproductive sites for planning strategies for its conservation in Brazil.
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https://cdnsciencepub.com/eprint/JS8GEVNTGVJJNMJPMZMM/full _______________________________________________________________________ Grassland degradation and fragmentation produced by land use have globally impacted biodiversity. In the Neotropics, the Pampas Grasslands have been greatly altered by agriculture and the introduction of exotic trees. To evaluate the effects of changing habitat features on native grassland fauna, we studied a breeding population of a ground nesting bird, the Spotted Nothura Nothura maculosa (Temminck, 1985) in a natural grassland under cattle-grazing in central-east Argentina. We estimated daily nest survival rate (DSR) and modeled it as a function of habitat (distance to habitat edges, cattle density and nest concealment) and temporal factors. Of the 80 nests found, 64 (80 %) failed, predation being the principal cause of failure. DSR was 0.874, estimating a cumulative survival of only 6.8 % throughout egg laying and incubation. DSR increased with distance to continuous forests and decreased with nest age. Nests located near forest edges could have increased predation risk because they are potentially exposed to forest dwelling predators in addition to grassland dependent ones. Considering the low success found and the ongoing invasion of exotic trees in the region, we encourage governments to protect large areas of grassland that ensure adequate nest success for tinamous and other ground nesting birds.
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Raptors are highly sensitive to environmental and human-induced changes. In addition, several species of raptors exist in considerably small numbers. It is thus critical to conserve raptors and their habitats across relatively larger landscapes. We examined the diurnal raptor assemblages and seasonality in a subtropical habitat in India’s northwestern Himalayas. Quantitative data on diurnal birds of prey and their habitat features across six distinct habitat types were collected from 33 sample sites. We observed 3,434 individuals of 28 diurnal rap- tors belonging to two orders and three families during a two-year survey from December 2016 to November 2018. A significant variation in bird species richness and abundance was found across habitats and seasons, with farmlands and winters being the most diverse and speciose. The generalized linear model, used to determine raptor community responses, indicated that elevation and proximity to dumping sites significantly affected the raptor abun- dance. The non-metric multidimensional scaling (NMDS) revealed significant differences in raptor assemblages across the habitat types. The study concluded that raptors’ persistence is largely determined by their preference for favourable feeding, roosting, and nesting opportunities. The presence of protected and habitat exclusive species validates the high conservation importance of these ecosystems, particularly the forest patches and farmlands, necessitating robust conservation and management measures in this part of northwestern Himalaya.
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Land-use changes due to agricultural intensification and climatic factors can affect avian reproduction. We use a top predator of agroecosystems, the American kestrel (Falco sparverius) breeding in nest boxes in Central Argentina as a study subject to identify if these two drivers interact to affect birds breeding. We analyzed their breeding performance across a gradient of agricultural intensification from native forest, traditional farmland to intensive farmland. The surface devoted to soybean was used as a proxy of agriculture intensification; however, it did not affect the breeding performance of American kestrels. Even though the presence of pastures was important to determine the probability of breeding successfully. Climatic variables had strong effects on the species breeding timing, on the number of nestlings raised by breeding pairs and on the probability of those pairs to breed successfully (raising at least one fledgling). Our results highlight the relevance of pastures and grasslands for American kestrel reproduction. These environments are the most affected by land-use change to intensive agriculture, being transformed into fully agricultural lands mostly devoted to soybean production. Therefore, future expansion of intensive agriculture may negatively affect the average reproductive parameters of American Kestrels, at least at a regional scale. Further research will be needed to disentangle the mechanisms by which weather variables affect kestrel breeding parameters.
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High mortality by electrocution has been suggested to be the main factor behind the reduction of several birds of prey populations across the world. Almost nothing is known, however, about the impact of power lines on this group of birds in the Neotropical Region. Here we estimate electrocution rates for birds on power lines covering both arid and semiarid biomes of central Argentina. We conducted six bi-monthly power line and raptor surveys throughout 355 km of lines and roads covering an area of approximately 12,000 km ² . We described the structural design of 3,118 surveyed electricity pylons. We found 34 electrocuted individuals of four bird families that constitute an annual bird electrocution rate of 0.011 bird/pylon/year. Bird electrocution occurred mostly on concrete pylons with jumpers above the cross-arm. Larger birds of prey had a higher electrocution rate than smaller species. The Crowned Solitary Eagle Buteogallus coronatus was disproportionately affected by this mortality source when compared with its low population density. Electrocution incidents occurred mostly in a few electric pylon designs that represent only 10.2 % of the power pylons monitored in the study area. Therefore, the change or modification of a small fraction of pylons would almost eliminate bird electrocution incidents in our study area. Our results prove that electrocution is a relevant cause of mortality for Crowned Solitary Eagles and urgent mitigating actions are needed to reduce this mortality factor.
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Large birds of prey, such as the Black-and-chestnut Eagle (Spizaetus isidori), are among the most threatened species, due to their high habitat requirements as top predators. In order to develop effective conservation plans for this group, more detailed knowledge of the different aspects of their biology and interaction with human communities is required. We evaluated the nestling diet of the Black-and-chestnut Eagle for three breeding periods using three different methods in the rural area of Gachalá-Cundinamarca, on the eastern slope of the Eastern Cordillera of Colombia. In addition, we surveyed people living in the study area to assess the existence of potential eaglehuman conflicts. Of the eight taxa recorded as prey, the Andean Guan (Penelope montagnii) was the most frequent (40%), while the House Chicken (Gallus gallus) contributed the greatest biomass (47%). Our surveys reveal an estimated yearly loss of one to two domestic fowl individuals per household, with 57% of owners surveyed claimed to have suffered losses. According to the survey results, inhabitants would prefer not to have the eagle breeding close to their houses (< 10 km), and would consider killing eagles if they preyed upon more than five domestic fowl individuals a year. To reduce the threat and the current human-eagle conflict in the area, it is important to consider "win-win" strategies, some of which are already being studied in the area, such as birdwatching initiatives.
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Large avian scavengers are among the most vulnerable vertebrates, and many of their populations have declined severely in recent decades. To help mitigate this marked reduction in abundance, supplementary feeding stations (SFS; colloquially termed "vulture restaurants") have been created worldwide, often without consideration of the scientific evidence supporting the suitability of the practice. SFS have been effective and important tools for conservation and reintroduction of avian scavengers. However, negative consequences can result from large aggregations of individual birds, disrupting intraguild processes and promoting density-dependent decreases in productivity. At the community level, SFS favor the congregation of predators (ie facultative scavengers), increasing predation risk on small- and medium-sized vertebrates in the vicinity of the SFS. These feeding stations might also affect processes of natural selection and even render populations maladapted to their natural environments. We also examine future scenarios for avian scavengers in relation to ecosystem services, to changes in agro-grazing economies and in land uses, and ultimately to rewilding landscapes where SFS play a controversial role.
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The 2015 feedlot consulting nutritionist survey is a collaborative project between New Mexico State University and Texas Tech University that focuses on summarizing the professional practices of consulting feedlot nutritionists and updates a 2007 survey. Forty-nine consulting feedlot nutritionists were asked to participate, of which 24 completed the survey. The nutritionists surveyed service over 14,000,000 cattle annually and were representatives from individual consulting practices (54.2%), corporate cattle feeding companies (20.8%), corporate feed manufacturing companies (20.8%), or a combination of consulting practices (4.2%). The survey was completed using a web-based survey tool and contained 101 questions that were divided into sections regarding general information about the consulting practice; general cattle management; receiving cattle management, diet adaption; mixers, feed mills, and feeding management; grains and grain processing; grain by-product use; roughage use; information about supplements and microingredients; liquid feed use; nutrient formulation; feed additive use; and information used as a basis for nutritional recommendations. In most cases, the results of the current survey were similar to those reported for the 2007 survey, with a few notable exceptions such as shifts in cattle numbers and preferences for specific feedstuffs. The present study introduced a number of new questions not included in the 2007 survey that focused on management strategies used in the receiving period. Data from this survey provide insight into current nutritional and management practices of consulting nutritionists and, as in past surveys, should be useful for informing national committees that make nutritional recommendations for cattle, as well as nutrition and management strategies employed within university research settings.
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Specialist predators are generally negatively impacted by habitat change. Predators that inhabit transformed areas are usually forced to diversify their diet and this departure away from traditional resources can have negative consequences for fitness and demographic parameters. We consider this relationship as it applies to Verreaux's eagles Aquila verreauxii, which is typically considered to be a highly specialised predator of hyraxes (Procavia and Heterohyrax spp.). We investigate diet in relation to land cover in two adjacent areas of South Africa and explore the links between diet diversity, the percentage of hyrax consumed, and the breeding performance of eagles. We also examine these same patterns using data from other studies. We found that diet diversity was greater in the agriculturally developed Sandveld region compared to the natural Cederberg region. Proportions of the three main prey types were correlated with the proportion of agriculturally developed land around the nest site. Breeding performance was correlated with the diet, but not in the manner expected, with breeding productivity being greater in regions with large diet diversity and a small proportion of hyrax in the diet. We found similar patterns when placing our results into a broader geographical context using other dietary studies of Verreaux's eagles, suggesting our results were not unique to our study system. Thus, our results suggest that diet diversification does not necessarily impinge on breeding performance in the presence of adequate alternative prey resources. This research adds to the growing number of studies suggesting that some predators may be adaptable up to a threshold level of habitat transformation. These results have implications for predicting changes on such species by anthropogenic habitat transformation and highlight the potential for agriculturally developed areas to maintain a conservation value when habitat heterogeneity is maintained.
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Ecoregion Conservation In recent years the conservation community has been promoting the design and implementation of biodiversity conservation actions at larger scales. WWF has embraced this approach, focusing conservation planning and action on ecoregions — relatively large units of land or water that contain a distinct assemblage of natural communities that share a large majority of species, dynamics, and environmental conditions. Since most ecological and evolutionary processes that sustain biodiversity occur at these larger scales, WWF has determined that ecoregions are the best units to design and implement biodiversity conservation actions. One of the key elements needed to implement ecoregion conservation is a Biodiversity Vision. A Biodiversity Vision is a planning tool, usually in the form of a document like this, aimed at guiding biodiversity conservation activities in the ecoregion. A Biodiversity Vision sets a number of biodiversity conservation goals based on widely-accepted principles of conservation biology, and identifies critical areas to be either conserved, managed, or restored in order to meet those goals. These areas are identified through a science-based process that relies on the best available biodiversity data and socioeconomic information. Through this process, we developed a Biodiversity Conservation Landscape that is represented in a map illustrating how the ecoregion would look in 50-100 years if we are successful in conserving biodiversity. This Biodiversity Conservation Landscape is a central piece of the Biodiversity Vision, and its representation in a map helps to focus conservation activities on those areas and to set specific targets that would render the best results for biodiversity conservation. The Upper Paraná Atlantic Forest—a critically endangered ecoregion In a worldwide ranking based on a comparative analysis of biodiversity data, WWF has identified the Global 200—the most outstanding ecoregions representing the full range of the Earth’s diverse terrestrial, freshwater, and marine habitats. The Atlantic Forests, a Global 200 ecoregion, is actually a complex of 15 terrestrial ecoregions that span the Atlantic coast of Brazil, extending westward into eastern Paraguay and northeastern Argentina. The Atlantic Forests are among the most endangered rainforests on earth, with only 7.4% of their original forest cover remaining, and this is in a highly fragmented landscape. They have been ranked as one of the most biologically diverse forests of the world. The southwestern portion of the Atlantic Forest constitutes the Upper Paraná Atlantic Forest ecoregion and is the focus of this Biodiversity Vision.
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Habitat loss and fragmentation intensify the effects of genetic drift and endogamy, reducing genetic variability of populations with serious consequences for wildlife conservation. The Harpy Eagle (Harpia harpyja) is a forest dwelling species that is considered near threatened and suffers from habitat loss in the forests of the Neotropical region. In this study, 72 historical and current samples were assessed using eight autosomal microsatellite markers to investigate the distribution of genetic diversity of the Harpy Eagle of the Amazonian and Atlantic forests in Brazil. The results showed that the genetic diversity of Harpy Eagle decreased in the regions where deforestation is intense in the southern Amazon and Atlantic Forest.
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Breeding productivity frequently shows variation across a species’ range or locally between different habitat types. Agricultural transformation generally has negative effects on biodiversity and often results in reduced prey abundance or increased foraging effort in top predators and, consequently, often reduces breeding productivity. Major factors that affect reproductive success also include climatic variables, breeding density, and timing of breeding. We explored the influence of agricultural transformation on a specialist raptor, Verreaux’s Eagle (Aquila verreauxii). From 2011 to 2014, we examined productivity in 2 adjacent populations in the Western Cape Province, South Africa: an unspoiled area of Fynbos vegetation with little human development (the Cederberg Mountains) and an agriculturally transformed area (the Sandveld region). Counterintuitively, breeding productivity was higher in the agricultural than in the natural site. In particular, the proportion of pairs that attempted to breed (i.e. breeding rate) was higher in the Sandveld (0.94 6 0.07 attempts pair􀀁1 yr􀀁1) than in the Cederberg (0.48 6 0.14 attempts pair􀀁1 yr􀀁1). Nesting success was also higher in the Sandveld (0.80 6 0.05 fledged young attempt􀀁1 yr􀀁1) than in the Cederberg (0.57 6 0.13 fledged young attempt􀀁1 yr􀀁1), and the probability of nesting successfully was related to the lay date (decreased success with later laying) and to the total cumulative rainfall up to 28 days after hatching (decreased success with increasing rainfall). Using the site-specific breeding rates to produce a population model, we found that in isolation, the Cederberg population is unlikely to be self-sustaining, but Verreaux’s Eagles breeding in the agriculturally developed Sandveld region are likely to be an important source population, despite occurring at a much lower density. These results, contrary to our expectations, suggest that Verreaux’s Eagle may be more adaptable to agricultural transformation than previously thought, with breeding performance in the agricultural site adequate to maintain the population.
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Coastal and inland surveys for the endemic and “Critically Endangered” Madagascar Fish Eagle Haliaeetus vociferoides were conducted in western Madagascar from Antsiranana in the north to Manja in the south during the 2005 and 2006 breeding seasons (May–October). Surveys covered typical Madagascar Fish Eagle habitat: lakes, rivers, mangroves, estuaries, and marine islands within their known distribution. In total, 287 individuals were encountered, including 98 breeding pairs (196 individuals), 23 breeding trios (69 individuals), 15 single adults and seven immature birds. Of these 287 birds, 128 individuals (44.6%) were observed on lakes; 116 (40.4%) in coastal areas, consisting of 103 (35.9%) in mangroves and 13 (4.5%) in estuaries; 32 (11.2%) on marine islands and 11 (3.8%) on rivers. There was an increase between surveys in 1995 and this study in the number of Madagascar Fish Eagles counted, from 222 to 287, and in the number of pairs from 99 to 121. This study confirms that the Madagascar Fish Eagle population is still low due to human persecution (hunting, collection of eggs and nestlings), overfishing and habitat destruction. We recommend monitoring fish eagles annually at the higher concentration sites to evaluate human activities and conducting a population survey every five years throughout western and northern Madagascar.
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Here we review the distribution of the Crested Eagle (Morphnus guianensis) in the Americas, and based on the Brazilian Harpy Eagle Conservation Program (PCGR) database, literature, online databases, zoos, wild and museum records, we provide an updated distribution map with 37 points outside the IUCN map; 16 were recorded close to the border of the map (up to 40 km), and do not expand or contribute to the distribution map. Far from the border (>40 km) we found 21 records, contributing to an expansion of the known range and habitat. At the northernmost extreme of distribution, the range was extended to southern Mexico; in Nicaragua, the range extension was farther south in the north, and two records extend the range to the southern border with Costa Rica. In Colombia, an old specimen is located between Darien Peninsula and the Perija Mountains. In Brazil a record from the ecotone between Cerrado and Gallery Forest, and another in an upland remnant of Atlantic Rainforest, expands the range towards central and southeastern Brazil, and to the Northeast, old records could expand the Atlantic Rainforest distribution towards the interior. © 2015, Sociedade Brasileira de Ornitologia. All rights reserved.
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Natural environments have been greatly transformed by human populations and activities and the responses of species to these changes vary. In human-dominated environments, birds may adopt behaviours that enable them to adjust to these novel habitats. We analysed the reproductive ecology of a common and human-tolerant bird of prey, the Chimango Caracara (Milvago chimango), in a peri-urban zone in central Argentina in response to different levels of human presence. A total of 34 nests were monitored. Nests were in dense colonies with a random distribution of nests within the colony. The reproductive output of Chimango Caracaras was not affected by levels of human presence at either the local scale (colony site) or within colonies (distance to neighbouring nests). However, the lower reproductive success in our study compared with that observed in natural habitats suggests that this species may be negatively affected by anthropogenic factors at a very local scale (i.e. a breeding colony in a peri-urban area) despite its behavioural plasticity and apparent tolerance to human presence.
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Rapid expansion and intensification of agriculture create challenges for the conservation of biodiversity and associated ecosystem services. In Argentina, the total row crop planted area has increased in recent decades with the expansion of soybean cultivation, homogenizing the landscape. In 2003 we started the first long-term, large-scale bird monitoring program in agroecosystems of central Argentina, in portions of the Pampas and Espinal ecoregions. Using data from this program, we evaluated the effect of land use and cover extent on birds between 2003-2012, accounting for imperfect detection probabilities using a Bayesian hierarchical, multi-species and multi-season occupancy model. We tested predictions that species diversity is positively related to habitat heterogeneity, which in intensified agroecosystems is thought to be mediated by food availability; thus the extent of land use and cover is predicted to affect foraging guilds differently. We also infer about ecosystem services provisioning and inform management recommendations for conservation of birds. Overall our results support the predictions. Although many species within each guild responded differently to land use and native forest cover, we identified generalities for most trophic guilds. For example, granivorous gleaners, ground insectivores and omnivores responded negatively to high proportions of soybean, while insectivore gleaners and aerial foragers seemed more tolerant. Habitat heterogeneity would likely benefit most species in an intensified agroecosystem, and can be achieved with a diversity of crops, pastures, and natural areas within the landscape. Although most studied species are insectivores, potentially beneficial for pest control, some guilds such as ground insectivores are poorly represented, suggesting that agricultural intensification reduces ecological functions, which may be recovered through management. Continuation of the bird monitoring program will allow us to continue to inform for conservation of birds in agroecosystems, identify research needed to reduce key uncertainties, and anticipate the effects of changes in agriculture in central Argentina.
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Latin America has the planet’s largest land reserves for agriculture and had the most rapid agricultural expansion during the twenty-first century. A large portion of the expansion replaced forests, as shown by many local and regional studies. However, expansion varied regionally and also replaced other land covers. Further, it is important to distinguish between changes in cropland and pastureland as they produce food at different levels of efficiency and intensity. We used thirteen years (2001–2013) of MODerate Resolution Imaging Spectroradiometer satellite imagery to characterize cropland and pastureland expansion at multiple scales across Latin America. From 2001 to 2013, 17% of new cropland and 57% of new pastureland replaced forests throughout Latin America. Cropland expansion from 2001 to 2013 was less (44.27 Mha) than pastureland (96.9 Mha), but 44% of the 2013 cropland total was new cropland, versus 27% of the 2013 pastureland total, revealing higher regional expansion rates of row crop agriculture. The majority of cropland expansion was into pastureland within core agricultural regions of Argentina, Brazil, Bolivia, Paraguay, and Uruguay. On the contrary, pastureland largely expanded at frontiers, such as central Brazil, western Paraguay, and northern Guatemala. As others have suggested, regional agriculture is strongly influenced by globalization. Indeed, we find an overall decrease in agricultural expansion after 2007, coinciding with the global economic slowdown. The results illustrate agricultural cropland and pastureland expansion across Latin America is largely segregated, and emphasize the importance of distinguishing between the two agricultural systems, as they vary in land use intensity and efficiency.
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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.
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Several studies conducted in neotropical islands have found that the intensity of human activity has altered the original structure and richness of bird communities, strongly affecting endemic species. Despite these effects, studies are limited, and lacking for raptors, in contrast to temperate and continental regions. During breeding and non-breeding seasons of 2012, roadside surveys and point counts were conducted in natural and human-transformed areas of the island of Cuba to determine whether or not raptors from an island show a pattern of ecological response to human activity similar to those observed in continental studies. Raptors showed strong variation in relation to habitat transformations, with lower richness, abundance, and density in the more extensively transformed areas. A total of 11 species was recorded, mostly in natural areas. Similar numbers of species were observed in coastal vegetation and cattle pasture habitat types within each zone. Nine species were detected in agriculture, while ten were found in forest habitat. A gradient of species-habitat was identified: Specialists/endemics tend to occur in natural areas, “intermediate species” in moderately modified areas and generalists in heavily modified areas. Generalists had higher abundances in anthropogenic areas, whereas specialists were found only in natural areas. Under insular conditions, land use changes can pose major threats for endemic and specialist raptors, seriously compromising their conservation. Endemic raptors do not cope well with habitat changes on the island, thus a rapid process of species impoverishment might be expected. Establishing a conservation program in Cuba is urgently needed.
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One contribution of 18 to a Theme Issue 'Assessing risks and impacts of pharmaceuticals in the environment on wildlife and ecosystems'. Global pharmaceutical consumption is rising with the growing and ageing human population and more intensive food production. Recent studies have revealed pharmaceutical residues in a wide range of ecosystems and organisms. Environmental concentrations are often low, but pharmaceuticals typically are designed to have biological effects at low doses, acting on physiological systems that can be evolutionarily conserved across taxa. This Theme Issue introduces the latest research investigating the risks of environmentally relevant concen-trations of pharmaceuticals to vertebrate wildlife. We take a holistic, global view of environmental exposure to pharmaceuticals encompassing terrestrial, freshwater and marine ecosystems in high-and low-income countries. Based on both field and laboratory data, the evidence for and relevance of changes to physiology and behaviour, in addition to mortality and reproductive effects, are examined in terms of the population-and community-level consequences of pharmaceutical exposure on wildlife. Studies on uptake, trophic transfer and indirect effects of pharmaceuticals acting via food webs are presented. Given the logistical and ethical complexities of research in this area, several papers focus on techniques for prioritizing which compounds are most likely to harm wildlife and how modelling approaches can make predictions about the bioavailability, metabolism and toxicity of pharmaceuticals in non-target species. This Theme Issue aims to help clarify the uncertainties, highlight opportunities and inform ongoing scientific and policy debates on the impacts of pharmaceuticals in the environment.
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The Eastern Imperial Eagle (Aquila heliaca Savigny 1809) reaches the western border of its range in the Carpathian Basin, which is the largest known population outside Russia and Kazakhstan. An increasing trend of this population in Hungary and also in the nearby areas of Slovakia has been reported since the 1980’s, when the number of breeding pairs supposedly reached the historical minimum. In this study we evaluated the dynamics of the Hungarian Imperial Eagle population between 2001 and 2009. As a result of the continuous increase of the population the monitoring program revealed 105 nesting pairs by 2009. While an expansion of the breeding area towards lowland agricultural habitats was observed, the ratio of pairs inhabiting the historical mountainous breeding habitats decreased from 50 % to only 15 % during the study period. The frequency of the two- and three-chick broods in respect to single-chick broods increased in comparison to the 1980-2000 period showing a higher average annual productivity of the population (1.15 fledglings per nesting pair). Besides the favourable changes in population trend and productivity, the area expansion in the recently occupied lowland habitats also raised several new threats to the population, such as the increased number of illegal poisoning incidents and more frequent collisions with vehicles.
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Reproductive success of raptor species is significantly affected by the quantity and/or quality of available prey. In our study we analysed prey composition of breeding imperial eagles (Aquila heliaca) in East Hungary, where 434 nesting events in 81 different territories had been monitored between 1995 and 2004. We identified 1297 prey items originating from 43 bird and 16 mammalian species (532 and 764 specimens, respectively). Three prey species, the brown hare (Lepus europaeus), the hamster (Cricetus cricetus) and the pheasant (Phasianus colchicus), seem to have especially important role in the diet of imperial eagles in Hungary, although their relative frequencies varied greatly among different regions. We found that eagles were less productive in a region where hamster was the main prey (West Zemplén Mts) as compared to a recently colonized hare-dominated region (Heves Plain), suggesting that hares may provide a better food source than hamsters. The increase of game species in the diet of imperial eagles could generate hostility in hunters. Possible conflict between nature conservation and small-game management may be resolved by raising public awareness and by common projects to improve hare and pheasant habitats.
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Organochlorine compounds (OC) are of interest in current biomonitoring studies because of their well-known persistence, accumulation capacity and the adverse effects they caused in the past. P,p’-DDE has been shown to cause severe reproductive failures and population declines in birds of prey. However, there are knowledge gaps regarding OC exposure for some species (e.g. harriers) and to the historical record and the broader picture. The main goal was to evaluate exposure to p,p’-DDE and PCBs in two raptor species: Montagu’s and pallid harriers (Circus pygargus and Circus macrourus), and to investigate if birds from different breeding areas and wintering grounds differ in pollutant levels. For this purpose, we collected blood of adult and nestling Montagu’s and pallid harriers breeding in the natural steppes of Kazakhstan, and adult and nestling Montagu’s harriers breeding in agricultural and natural habitats of Spain, in 2007-2008. We determined the blood concentrations of p,p’-DDE and PCBs. Adult harriers generally showed higher concentrations of p,p’-DDE and PCBs than nestlings, probably because they had more time for a progressive accumulation of these compounds due to a higher intake than excretion rate. The p,p’-DDE concentrations in adults were equivalent in all the studied areas. The ratio p,p’-DDE/PCB 153 was higher in adults than in nestlings, suggesting that a portion of the p,p’-DDE in adult harriers may have come from p,p'-DDT applied in the past in the wintering areas. Overall, the concentrations of p,p’-DDE and ∑PCBs reported were generally low and below any demonstrated threshold of harm.
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Persistent pollutants such as organochlorine compounds (OCs) have been highlighted as a cause of population decline in avian predators. Understanding patterns of OCs contamination can be crucial for the conservation of affected species, yet little is known on these threats to African raptors. Here we report on OC concentrations in an endangered predator endemic to southern Africa, the Black Harrier Circus maurus. Blood samples were collected in 2012-2014 from wild nestlings (n = 90) and adults (n = 23) in south-western South Africa, where agriculture and urbanization have developed rapidly since the 1950s. Polychlorinated biphenyl (ΣPCB) and dichlorodiphenyltrichloroethane (ΣDDT, for p,p’-DDT + p,p’-DDE) were detected in 79% and 84% of sampled individuals, respectively, with varying concentrations among demographic groups: nestlings had significantly higher ΣPCB and p,p’-DDT concentrations than adults, while adults had higher levels of p,p’-DDE than nestlings. Levels of ΣPCB significantly increased with an index of electric transformer density, a measure of the number and power of electric transformers around active nests. We propose this index as a useful tool for assessing ΣPCB exposure risk in other wildlife. Levels of p,p’-DDE significantly increased with the proportion of wetlands within the breeding territory, and also with the proportion of bird biomass in the diet. No association was found between OC levels and the protected area status of nesting sites. Physiological effects of contaminants were also manifest in increased white blood cell counts with higher p,p’-DDT levels. Heterophil to lymphocyte ratio increased with higher ΣPCB levels, suggesting increased physiological stress and reduced immunity in contaminated individuals. Our results suggest that OCs are still a current cause of concern for endangered Black Harriers, as well as other sympatric predators.
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Wildlife exposure to pharmaceuticals can occur through contaminated water, and through the excreta and carcasses of medicated livestock, with potential for bioaccumulation and transfer through food webs. We evaluated whether nestling exposure to pharmaceuticals can occur from food delivered to nests in the golden eagle (Aquila chrysaetos), a top predator and facultative scavenger. Despite the fact that diet analysis suggests an apparently low dependence on livestock carcasses reduced to two piglets remains (1.5% of food remains, n=134), a high proportion of nestlings (71%, n=7) showed fluoroquinolone residues in plasma, mostly enrofloxacin, which is exclusively used in veterinary treatments. The occurrence and concentration (54.5±6.6μg·L(-1)) of fluoroquinolones in plasma was similar to those found in the nestlings of three vulture species largely dependent on livestock carcasses obtained at supplementary feeding stations, which are managed for the conservation of their populations. Although the number of analysed eaglets is comparatively small, the fact that enrofloxacin was found in all nests sampled in three breeding seasons suggest an exposure to the drugs similar to that of vultures. An underestimation of the role of carrion, especially from small piglets whose consumption may have gone unnoticed, and the predation of semi-domestic prey and generalist prey exploiting carcasses of medicated livestock, can contribute to explaining the unexpectedly high occurrence of these drugs in eaglets.
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Predation on semidomestic reindeer (Rangifer tarandus) by large carnivores has become a severe problem for Saami-reindeer owners in central Norway over the last decades. Efforts have been made to quantify the problem to improve the large-carnivore management system. The golden eagle (Aquila chrysaetos), which is a protected species in Norway, has been identified by reindeer owners as a significant predator on semidomestic reindeer, especially calves. We investigated predation by the golden eagle on semidomestic reindeer in central Norway using mortality-sensing radiocollars mounted on 853 reindeer. We observed 9 calf and 3 adult female deaths from golden eagle predation. Under certain environmental conditions, the golden eagle appears to be an effective predator on adult and young reindeer, especially when smaller prey species are less abundant.
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Although habitat loss and fragmentation are widely regarded as major factors contributing to the decline of many populations, the relative importance of each phenomenon is seldom evaluated. Some researchers have questioned the generality of responses to habitat fragmentation, given variation in life history characteristics, the natural dynamics of systems, and land use patterns. Furthermore, a fundamental mismatch may exist between ecological theory, with its emphasis, on the spatial configuration of habitats, and empirical observations of population response. Nevertheless, the paucity of quantitative land management guidelines often leads to inappropriate generalizations of conservation paradigms to regional issues. We reviewed the empirical evidence for true fragmentation effects in boreal bird communities in Fennoscandia and Canada, and concluded that most responses may be attributed to pure habitat loss in landscapes where forest harvesting is the dominant land use practice. In these dynamic landscapes, total forest cover may not change, and predicting patterns of species decline requires identification of the habitats and species of concern. We constructed simple empirical models of benchmark communities in boreal forests of Finland and Canada based on species composition, species abundance distribution, and habitat requirements, in order to identify features of bird species sensitive to the loss of older forests. These models require a solid understanding of the underlying structure of the community of interest, and predict species loss based on a random-sample hypothesis. Our results were consistent with observed patterns of bird population decline and species loss in these regions. This approach provides null models for comparison with habitat remnants in order to test for fragmentation effects, and a basis for more detailed exploration of population dynamics and persistence in these systems. The results of our review and analyses indicated that system- and species-specific considerations are important when assessing the potential outcome of habitat loss and fragmentation on regional biota. Indiscriminate application of conservation paradigms may lead to misguided research efforts and poor management guidelines.
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To provide insight into raptor declines in western Africa, we investigated associations between land-use and raptor distribution patterns in Cameroon. We examined the role of breeding distribution, species' migratory mobility, diet, body size, and thus area requirements, on 5-km scale patterns of raptor richness and abundance. We recorded 15,661 individuals, comprising 55 species during road surveys, spanning four annual cycles. Results revealed evidence for the importance of National Parks (N.P.'s), natural vegetation, humans, and cotton in shaping raptor assemblages, but responses differed between functional groups and biogeographical zones. Human populations and natural habitat, interacting with zone, were important predictors of Afrotropical raptor richness, and N.P.'s of Palearctic raptor richness. Areas cleared of natural habitat in the Guinea zone had comparatively rich and abundant large, small sedentary and migratory Afrotropical raptor assemblages, but humans limited positive effects. Palearctic raptor abundance peaked at higher levels of human land-use than Afrotropical raptors. Vertebrate-hunting Palearctic raptor richness was positively associated with cropland, while cotton and human land-use in the Inundation zone had a stronger negative impact on insectivorous Palearctic raptors. Richness of large sedentary raptors declined with increasing distance to N.P.'s, contrary to communal scavenger richness, which increased with human populations. Humans, habitat loss and cotton in the Inundation and Sudan zones had similar, negative effects on small sedentary and small migratory Afrotropical raptor assemblages. We conclude that increasing human populations, natural vegetation loss, and expanding cotton will negatively affect the majority of Afrotropical and insectivorous Palearctic raptors, while vertebrate-hunting Palearctic raptors may benefit from cropland expansion.
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The common vole, considered a rodent pest when overabundant in agricultural areas, was traditionally absent from the agricultural plains of Castilla-y-León, NW Spain. However, it rapidly invaded ca. 50.000 km2 of agricultural land, where regular outbreaks have caused crop damages and conflict with farmers. To better understand the factors that triggered this massive invasion of previously unoccupied habitats, we studied the associations between the common vole range expansion and changes in climate and land uses in the region since the 1970s. We found long-term trends in climate, with some changes that could have helped the range expansion (increased fall precipitation and winter temperature) and other changes that may have impaired it (reduced summer precipitation and increased summer temperatures). Dramatic changes in land use also took place prior to and during the invasion period (marked increases in irrigated and green herbaceous crops such as alfalfa, which are preferred habitats for voles). We found strong associations between changes in vole distribution and the extent of green crops (irrigated crops and alfalfa) at regional level. The colonization probability of a given agrarian county increased with the extent of green crops, particularly so when vole presence in neighbouring counties was lower, and tended to decrease with increasing livestock abundance. Land use changes, especially increases in irrigated crops and alfalfa, appear to be amongst the main drivers behind the vole range expansion. We discuss these findings in relation to the social conflicts and management challenges that arose from the recent invasion of agricultural areas by crop-damaging common voles.
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Indonesia contributes significantly to deforestation in Southeast Asia. However, much uncertainty remains over the relative contributions of various forest-exploiting sectors to forest losses in the country. Here, we compare the magnitudes of forest and carbon loss, and forest and carbon stocks remaining within oil palm plantation, logging, fiber plantation (pulp and paper), and coal mining concessions in Indonesia. Forest loss in all industrial concessions, including logging concessions, relate to the conversion of forest to non-forest land cover. We found that the four industries accounted for ∼44.7% (∼6.6 Mha) of forest loss in Kalimantan, Sumatra, Papua, Sulawesi, and Moluccas between 2000 and 2010. Fiber plantation and logging concessions accounted for the largest forest loss (∼1.9 Mha and ∼1.8 Mha, respectively). Although the oil palm industry is often highlighted as a major driver of deforestation, it was ranked third in terms of deforestation (∼1 Mha), and second in terms of carbon dioxide emissions (∼1,300 – 2,350 Mt CO2). Crucially, ∼34.6% (∼26.8 Mha) of Indonesia's remaining forests is located within industrial concessions, the majority of which is found within logging concessions (∼18.8 Mha). Hence, future development plans within Indonesia's industrial sectors weigh heavily on the fate of Southeast Asia's remaining forests and carbon stocks.This article is protected by copyright. All rights reserved.