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Foraging behavior of a guild of Neotropical vultures
... Considering the differences in their primary sensory organs and environmental factors, there are significant differences in dietary composition between the Old and New World vultures (Table 1). The Old World vultures tend to eat larger carcasses, including larger ungulates such as hippopotami, horses, and buffalo, while the New World vultures (Koford, 1953;Wallace and Temple, 1987;Lemon, 1991;Houston, 1994). Condors prefer to eat viscera and muscle, while Black Vultures remove flesh from bones using their rasp-like tongue and tend to feed on skin and harder tissues (Wallace and Temple, 1987;Nielsen, 2006). ...
Vultures are the only obligate scavengers among extant vertebrates. They provide valuable ecological services in ecosystems through removing carcasses, thus preventing the growth of other scavenger populations and the spread of pathogens. Moreover, their specific diets expose them to various deadly pathogens, which makes them potential candidates for studying molecular adaptations required to survive this extremely specialized scavenging habit. In this review, we summarize the morphological characteristics and behavioral habits, origin and phylogeny, and molecular adaptations to scavenging in both Old and New World vultures. The two groups of vultures share a similar appearance, indicative of convergent evolution. Vultures have experienced different degrees of specialization in their sensory organs; Old World vultures depend on sight, while New World ones depend on both smell and sight. Combined fossil records and molecular data suggest that vultures evolved independently, with distinct phylogenetic positions. We also explored their adaptation to scavenging in facial and intestinal microbiomes, gastric acid secretion and immunity. Compared with the facial microbiome, the intestinal microbiome had a lower diversity, dominated by Fusobacteria and Clostridia. The phages and single invertebrate species Adineta vaga, which feeds on dead bacteria and protozoa, present in the gut suggest a possible alternative defense mechanism. Several genes involved in gastric acidic secretion (including ATP4B, SLC26A7 and SST) and immunity (including BCL6, STING, and TLRs) undergoing positive selection likely have essential roles in eliminating invasive pathogens and initiating an innate immune response. Taken together, this review presents the current research status of vultures and highlights the use of vultures as a model for exploring molecular adaptations of dietary specialization in birds. It also provides a theoretical basis for the study of the genetic mechanisms of vultures to scavenging, and contributes to the formulation of vulture conservation strategies.
... Very often studies on olfaction capacity of turkey vultures draw contrasting comparisons with the black vulture (Coragyps atratus), a species of the same family, distributed nearly among the same range but presenting less obvious anatomical adaptations for the sense of smell (Bang 1964;Stager 1964;Houston 1986). In experiments where carrion was placed under dense forest cover, turkey vultures typically arrived first but became rapidly outnumbered by black vultures and eventually displaced from the feeding sites (Houston 1986(Houston , 1988Lemon 1992;Byrne et al. 2019). This suggests that while turkey vultures rely on the sense of smell and cover large areas to search for food, black vultures are opportunists, mostly tracking other scavengers to find food ). ...
New World vultures have been considerably studied regarding their sense of smell. Cathartes species present a remarkable development of their olfactory apparatus, and experiments conducted with the turkey vulture (Cathartes aura) demonstrated that they can locate carrion exclusively by smell at considerable distances. Black vultures (Coragyps atratus), because of their less developed olfactory apparatus, have been compared with the turkey vulture as a phylogenetically related species lacking the sense of smell. However, little evidence from behavioural studies supports the lack of olfaction of black vultures. We conducted a field experiment where we presented urban black vultures a binary choice of decaying fish and sand (serving as control) inside plastic bags. Birds chose the fish bait in 81% of the times they approached the plastic bags. The probability of reaction decreased significantly with the distance between the birds and the fish bait, being virtually null at 40–50 m away. Furthermore, birds clearly reacted more when the fish presented higher decaying time (7 compared to 2 days). These results show that olfaction is not only used by black vultures but is probably the most relevant sense when they search for food hidden in plastic bags and in piles of unsorted waste, which is the most common foraging environment for this species in urban areas where they are very abundant.
... In closed rain forest, king vultures have been also claimed to engage in transect soaring at high altitude to keep track of the activities of Cathartes vultures, which locate carrion by smell (Houston 1988). However, in other areas with more open vegetation king vultures are often the first to arrive at carcasses (Lemon 1991). This points towards skills to detect food both independently and through inter-specific social information use. ...
Despite important recent advances in cognitive ecology, our current understanding of avian cognition still largely rests on research conducted on a few model taxa. Vultures are an ecologically distinctive group of species by being the only obligate carrion consumers across terrestrial vertebrates. Their unique scavenging lifestyle suggests they have been subject to particular selective pressures to locate scarce, unpredictable, ephemeral, and nutritionally challenging food. However, substantial variation exists among species in diet, foraging techniques and social structure of populations. Here, we provide an overview of the current knowledge on vulture cognition through a comprehensive literature review and a compilation of our own observations. We find evidence for a variety of innovative foraging behaviors, scrounging tactics, collective problem-solving abilities and tool-use, skills that are considered indicative of enhanced cognition and that bear clear connections with the eco-social lifestyles of species. However, we also find that the cognitive basis of these skills remain insufficiently studied, and identify new research areas that require further attention in the future. Despite these knowledge gaps and the challenges of working with such large animals, we conclude that vultures may provide fresh insight into our knowledge of the ecology and evolution of cognition.
... Currently, most studies indicate that King vultures follow the Cathartes vultures to carcasses (Houston 1984(Houston , 1994Beason, 2003). Lemon (1991) nevertheless found that that King vultures located carrion in dense forest, where Cathartes vultures were absent. However, Lemon (1991: 700) notes that 'Little is known about the foraging behavior or physiology of King Vultures,' although there is a general acknowledgment that it is a forest specialist (see also Schlee, 1995). ...
Large carnivores such as pumas are often killed in conflicts with humans because they prey on domestic livestock. Habitat loss, partly driven by the increasing use of traditional pasture systems, makes livestock vulneracle to puma attacks. The aim of this study was describe the conflict between local farmers and pumas in a mosais of Protected Areas in southern Brazil. We hypothesized that the farmer's preception, knowledge and attitudes towards the conflict with pumas is affected by socioeconomic variables, such as age, educaton, monthly income and farming experience. Forty-five face-to-face interviews with local farmers were performed in 2011, using a structured questionnaire with 16 open and 26 closed questions focusing on the perception farmers. Our results show that the majority of the local population considered the conflict with pumas a serious problem and thought that attacks by pumas on domestic herds shoud be controlled with the involvement of government authorities. Financial losses caused about pumas attacks on farms did not inflence the attitudes of farmers, and knowledge abou pumas was more inluenced by social variables such as age and educational level. Meetings with the local Rural Consulting Council revelated that conflict with pumas still remains in the region. In this context, a long-term educational program with local farmers is highly recommended, focused on engaging the community in the discussion about possible mitigations tools. Conservation wildlife depends on the ability to provaide decision makers with academic and traditional knowledge which could be build bridges between the commnunity and Environmental Agencies.
... Currently, most studies indicate that King vultures follow the Cathartes vultures to carcasses (Houston 1984(Houston , 1994Beason, 2003). Lemon (1991) nevertheless found that that King vultures located carrion in dense forest, where Cathartes vultures were absent. However, Lemon (1991: 700) notes that 'Little is known about the foraging behavior or physiology of King Vultures,' although there is a general acknowledgment that it is a forest specialist (see also Schlee, 1995). ...
INTRODUCTION
This book is edited by two environmental scientists with interests in GIS and remote
sensing applications, forest, and habitat change, and large animal ecology. It examines
the cutting-edge issues related to animal and habitat ecology research and
management, with case studies across Asia, the Americas, Africa, and Europe. The
topics are based on research and reviews of specific and general topics covering the
habitats as well as the species of importance in selected case studies, and the overall
general scenarios. The chapters of the book are written by leading academic and field
experts, who discuss their skills and research findings. The field covered is vast, so
selectivity enters, based on concurrent and relevant subjects, such as field research
techniques, nature-society relations, and chemistry in conservation biology and policy.
The chapters focus on cases as varied as vultures, storks, waterbirds, pumas or
cougars, and elephants, and research techniques such as genetics and GIS.
Technological developments, such as GIS and remote sensing, and some genetic
methods have altered the nature of ecological research. These include the utility of
GIS, and the related techniques of remote sensing, which allow more precise and
accurate measurements and consequently more informed and reliable results.
Species distribution modeling enables evaluations of habitat suitability and the impacts
of habitat alteration and the requirements for the improvement of animal conservation.
Integrated research, including the interfacial studies of social and natural sciences, is
increasingly important in ecological research, as disciplinary boundaries break down and
hybrid disciplines emerge. Simultaneously, chemical and genetic studies are
increasing in importance, with applications in the interfaces of the ecological, social, and medical sciences.
The topics covered in this book may contribute to the scientific understanding of
different, relevant topics on research methods on ecology and conservation biology.
This is especially the case, considering the wide selection of research topics in widely
varying contexts. Strands may emerge from these selected topics that may inform
further research and development in varied areas. These research findings may be
replicable in the different contexts to contribute to the objectives of ecological
sustainability. The results and conclusions presented, and the strategies
recommended in different chapters will help the policymakers and decision
implementers, scientists, resource managers, research scholars, and other
stakeholders to attain effective and sustainable animal conservation and habitat
... Therefore, solitary animals usually forage alone (Bearder 1987). However, they may still be aggregating together around the same food source, such as vultures around a cadaver (Lemon 1991), or terns above a fish school close to the surface (McLeay et al. 2010). Such aggregations of foraging animals are sometimes considered being involved in passive cooperation, although this is not a form of cooperative behaviour as defined above (Bailey et al. 2013). ...
Cooperative hunting involves individual predators relating in time and space to each other’s actions to more efficiently track down and catch prey. The evolution of advanced cognitive abilities and sociality in animals are strongly associated with cooperative hunting abilities as has been shown in lions, chimpanzees, and dolphins. Much less is known about cooperative hunting in seemingly unsocial animals, such as the harbour porpoise (Phocoena phocoena (Linnaeus, 1758)). Using drones, we were able to record 159 hunting sequences of porpoises, out of which 95 sequences involved more than one porpoise. To better understand if the harbour porpoises were individually attracted by the fish school or formed an organized hunting strategy, the behaviour of each individual porpoise in relation to the targeted fish school was analysed. The results indicate role specialization, which is considered the most sophisticated form of collaborative hunting and only rarely seen in animals. Our study challenges previous knowledge about harbour porpoises and opens up for the possibility of other seemingly non-social species employing sophisticated collaborative hunting methods.
Scavenging constitutes an understudied energy pathway in terrestrial ecosystems, with important connections to disease ecology. A prevailing null hypothesis in scavenging ecology is that carcasses serve as a risk-free meal for whatever animal first encounters them on the landscape. We tested this hypothesis by focusing on a suspected risk that scavengers would face at carcasses: the risk of pathogen exposure. We conducted field trials with mouse carcasses in which we manipulated potential cues to pathogen risk and then monitored scavenger foraging decisions. Separately, we studied pathogen and commensal bacteria dynamics within mouse carcasses through time in the laboratory to better understand how carcass age might impact pathogen risk to scavengers. A visual cue to pathogen risk in the field (carcasses deployed in groups of 7 in 1 m²) caused facultative vertebrate scavengers to pass on the opportunity to feed at a rate six-times higher than for carcasses deployed singly (46.9% vs. 7.7%), suggesting an ability to perceive cues to pathogen risk at carcasses. The cues to carcass age, however, produced no effect on facultative scavenger behavior in our field trials. Laboratory trials demonstrated that both commensal enteric bacteria and a known pathogen (Listeria monocytogenes) increased at least through bloat and active decay stages in carcasses, suggesting that cues to carcass age may not help scavengers reduce pathogen risk early in decomposition. In providing evidence counter to the free meal hypothesis, our results support the continued formation of an alternative risk-based framework to understand scavenger behavior at carcasses.
The ecological role of scavenging is underestimated, in part, because of limited data on facultative scavengers. Here, we describe a keel-billed toucan (Ramphastos sulfuratus) sequestering vertebrate carrion ~1 m off the ground. This observation is the first record of a toucan species supplementing their diet with carrion, and expands the list of facultative scavengers in the Neotropics, an area where scavenging is poorly understood. We caution that vertebrate remains found in gut-content analyses for toucans may be from scavenging, and we highlight that the consumption of vertebrate carrion by toucans could have landscape-level implications in the redistribution and movement of carcass nutrients and energy.
Resumen
El papel ecológico de los carroñeros usualmente se subestima debido, en parte, a la falta de datos robustos sobre carroñeros facultativos. En este trabajo describimos un tucán pico iris (R. sulfuratus) alimentándose de carroña de vertebrados a ~ 1 m del suelo. Esta observación es el primer registro de una especie de tucán que complementa su dieta con carroña, y amplía la lista de carroñeros facultativos en el Neotrópico, un área donde información ecológica sobre carroñeros es precaria. Llamamos la atención que los restos de vertebrados que se encuentran en los análisis del contenido intestinal de los tucanes pueden provenir del consumo de carroña, y destacamos que el consumo de carroña de vertebrados por parte de los tucanes podría afectar el flujo de los nutrientes y la energía proveída por la carroña.
Scavenging of carrion is essential to terrestrial ecosystems and can shape food webs and behavior. The prevalence and importance of scavenging has often been underestimated and overlooked in food web studies. Small-mammal carrion is even less studied and difficult to estimate, especially in the Neotropics. This project explored small-mammal carcass scavenging in a Neotropical, mid-elevation rainforest, and specifically studied the rate of carcass removal by scavengers, how the conspicuousness and weight of carcasses affect scavenging, and what vertebrate scavengers utilize this carrion resource. I deployed 194 mouse carcasses of various weights, above and below the leaf litter, and surveyed them daily until disappearance. I paired each carcass with a trail camera to help identify vertebrate scavengers. A general linear model analysis showed that most mouse carcasses disappeared within 1 to 2 days. Carcasses above the leaf litter were removed quicker and larger mice generally lasted longer. Only 6.25 % of the carcasses were removed by vertebrates. Most carcasses were removed by something too small to trigger the trail cameras, likely scarab beetles. The results of this study show that small-mammal carcasses are a sought-after resource in Neotropical forests, and that invertebrates are able to quickly hoard and secure small carrion more efficiently than vertebrate scavengers. A better understanding of scavenging ecology in Neotropical forests will help in developing a broader framework of the trophic interactions within and across ecosystems.
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