Article

Food searching in Griffon Vultures

April 2008
African Journal of Ecology 12(1):63 - 77

DOI:10.1111/j.1365-2028.1974.tb00107.x

Authors:

Observations are presented on food searching in griffon vultures. To locate food directly, griffon vultures do not use a sense of smell but rely on vision. However, most birds locate carcasses indirectly—by watching the activities of neighbouring birds. The method of food searching is described and the number of birds which arrive at a carcass is shown to depend on the amount of food that is available. Birds do not hold feeding ranges, but travel widely during food searching, one bird travelling 180 km in 6 days. The density of searching birds varies greatly according to the density of ungulates in an area, birds being most numerous over high ungulate concentrations. The altitude at which birds search also varies, birds flying at higher altitudes over areas of low ungulate density and at lower altitudes over ungulate concentrations. These variations in searching density and height are shown to affect the efficiency of food searching. Carcasses are located rapidly and the food consumed quickly in high ungulate density areas, while in low ungulate density conditions carcasses can take a long time to be located. It is concluded that griffon vultures are more likely to find food and are better able to compete with mammalian competitors by searching over migratory ungulate herds than over areas containing resident ungulate species. Their adaptations for gliding flight enable these birds to follow these migratory ungulates throughout the year.

Advantages and disadvantages of using social information for carcass detection–A case study using white-backed vultures

Article

Full-text available

Jan 2025
ECOL MODEL

We are what we eat, plus some per mill: Using stable isotopes to estimate diet composition in Gyps vultures over space and time

Article

Full-text available

Mar 2022

Dietary studies in birds of prey involve direct observation and examination of food remains at resting and nesting sites. Although these methods accurately identify diet in raptors, they are time‐consuming, resource‐intensive, and associated with biases from the feeding ecology of raptors like Gyps vultures. Our study set out to estimate diet composition in Gyps vultures informed by stable isotopes that provide a good representation of assimilated diet from local systems. We hypothesized that differences in Gyps vulture diet composition is a function of sampling location and that these vultures move between Serengeti National Park and Selous Game Reserve to forage. We also theorized that grazing ungulates are the principal items in Gyps vulture diet. Through combined linear and Bayesian modeling, diet derived from δ¹³C in Gyps vultures consisted of grazing herbivores across sites, with those in Serengeti National Park consuming higher proportions of grazing herbivores (>87%). δ¹³C differences in vulture feather subsets did not indicate shifts in vulture diet and combined with blood δ¹³C, vultures fed largely on grazers for ~159 days before they were sampled. Similarly, δ¹⁵N values indicated Gyps vultures fed largely on herbivores. δ³⁴S ratios separated where vultures fed when the two sites were compared. δ³⁴S variation in vultures across sites resulted from baseline differences in plant δ³⁴S values, though it is not possible to match δ³⁴S to specific locations. Our findings highlight the relevance of repeated sampling that considers tissues with varying isotopic turnover and emerging Bayesian techniques for dietary studies using stable isotopes. Findings also suggested limited vulture movement between the two local systems. However, more sampling coupled with environmental data is required to fully comprehend this observation and its implications to Gyps vulture ecology and conservation.

We are what we eat, plus some per mill: Using stable isotopes to estimate diet composition in Gyps vultures over space and time.

Preprint

Full-text available

Oct 2021

1. Dietary studies in birds of prey involve direct observation and examination of food remains at resting and nesting sites. Although these methods accurately identify diet in raptors, they are time-consuming, resource-intensive, and associated with biases from the feeding ecology of raptors like Gyps vultures. Our study set out to estimate diet composition in Gyps vultures informed by stable isotopes that provide a good representation of assimilated diet from local systems. 2. We hypothesized that differences in Gyps vulture diet composition is a function of sampling location, and that these vultures move between Serengeti National Park and Selous Game Reserve protected areas to forage. We also, theorised that grazing ungulates are the principal items in Gyps vulture diet. 3. Through combined linear and Bayesian modelling, diet-derived from 13C in Gyps vultures consisted of grazing herbivores across sites, with those in Serengeti National Park consuming higher proportions of grazing herbivores (> 87%). 13C differences in vulture feather subsets did not indicate shifts in vulture diet and combined with blood 13C, vultures fed largely on grazers for ~159 days before they were sampled. Similarly, 15N values indicated Gyps vultures fed largely on herbivores. 34S ratios separated where vultures fed when the two sites were compared. 34S variation in vultures across sites resulted from baseline differences in plant 34S values, though it is not possible to match 34S to specific locations. 4. Our findings highlight the relevance of repeated sampling that considers tissues with varying isotopic turnover and emerging Bayesian techniques for dietary studies using stable isotopes. Findings also suggested limited vulture movement between the two local systems. However, more sampling coupled with telemetry is required to fully comprehend this observation and its implications to Gyps vulture ecology and conservation.

Unravelling the decision making of foraging vultures: insights from a field experiment

Article

Full-text available

Apr 2025

Optimal Foraging Theory (OFT) integrates both the consumer and the resource, yet their simultaneous assessment is uncommon. Vultures represent an ideal model for OFT studies because carrion requires no capture effort and minimal handling, allowing them to focus primarily on food searching. Here, we combined GPS tracking of 61 Iberian griffon vultures (consumers) with photo-trapping monitoring of 49 carcasses (resources) to assess the determinants of vulture foraging and the consequences for carrion consumption in two areas with different carrion abundances. First, we determined the importance of different factors (distance to the resource, hunger and competition) in the decisions of individuals of whether to descend or not on a carcass. Second, we compared carrion consumption patterns (time of carcass discovery and consumption, and maximum number of vultures gathered around the carcass) between areas. We found that distance, rather than hunger, is the primary factor determining whether a vulture descends to a carcass. In parallel, carrion was consumed similarly in areas with different resource availabilities. These findings indicate that vultures tend to eat whenever a nearby opportunity arises, consistent with a type-I functional response.

Identifying suitable reintroduction sites for the White-rumped Vulture (Gyps bengalensis) in India's Western Ghats using niche models and habitat requirements

Article

Sep 2020
ECOL ENG

Once one of the most abundant raptors in the world, the White-rumped Vulture (Gyps bengalensis) has faced a drastic population decline across its global range for the past three decades. In India, the main cause of this decline has been the accidental ingestion of the non-steroidal anti-inflammatory drug diclofenac through livestock carcasses. However, some breeding populations still survive in the forested landscapes of India's Western Ghats. But these populations have also been facing several anthropogenic threats recently, and now show a declining population trend. The two possible conservation strategies for G. bengalensis are to ban diclofenac and develop further captive breeding and reintroduction programs. In this context, we modelled potential re-introduction sites for the species in the Western Ghats by considering its key habitat features and ecological niche models to maximise the likelihood of its long-term regional persistence. Models were developed for current and future climate change scenarios using nesting and foraging occurrence records. Our models predict climatically stable habitats under three climate change scenarios (Representative Concentration Pathways; RCP 2.6, RCP 4.5, and RCP 8.5) for three future time periods (2030s, 2050s, and 2080s). The primary determinants of nest-site selection by G. bengalensis evaluated using Generalized Linear Models (GLMs) revealed a preference for larger trees closer to water sources. Based on our findings, we suggest possible reintroduction sites in the southern Western Ghats that are climatically stable in the future time periods. Our approach can encourage policymakers to prioritize sites for future species management in the wild. The key results and its implications on conservation of G. bengalensis populations within the Western Ghats hotspot are further discussed in detail.

Large home range scavengers support higher rates of carcass removal

Preprint

Full-text available

Feb 2020

Vertebrate scavenger communities vary in species composition across the globe, and include a wide array of species with diverse ecological strategies and life-histories that support essential ecosystem functions, such as carrion removal. While previous studies have mostly focussed on how community aspects such as species richness and composition affect carrion consumption rates, it remains unclear whether this important function of scavengers is better explained by the dominance of key functional traits or niche complementarity as a result of a diverse functional representation. Here, we test three competitive hypotheses to assess if carrion consumption in vertebrate scavenger communities depends on: i) the presence of key dominant traits (functional identity hypothesis), ii) functional diversity that promotes niche complementarity (functional diversity hypothesis), or iii) the accumulation of individuals and species, irrespective of their trait representation (functional equivalence). To explore these hypotheses, we used five study areas in Spain and South Africa, which represent a gradient of scavenger biodiversity, i.e., ranging from communities dominated by facultative scavengers, such as generalists and meso-predators, to those including vultures and large carnivores. Within study areas, traits that characterise obligate scavengers or large carnivores (e.g. mean home range, proportion of social foragers) were positively linked to rapid carrion consumption, while the biomass of functional groups including facultative scavengers were either weakly or negatively associated with carrion consumption. When combining all study areas, higher rates of carrion consumption were related to scavenger communities dominated by species with large home ranges (e.g. Gyps vultures), which was found to be a key trait. In contrast, metrics describing functional diversity (functional dispersion) and functional equivalence (species richness and abundance) had lower predictive power in explaining carrion consumption patterns. Our data support the functional identity hypothesis as a better framework for explaining carrion consumption rates than functional diversity or equivalence. Our findings contribute to understanding the mechanisms sustaining ecosystem functioning in vertebrate communities and reinforce the role of obligate scavengers and large carnivores as keystone species in terrestrial ecosystems.

Studying Movement of Avian Scavengers to Understand Carrion Ecology

Chapter

Jul 2019

Scavenging is a key process in the ecosystems. Studying foraging movements of obligate scavengers such as vultures can contribute to a better understanding of the scavenging-related patterns and processes. Here we review methods that can be used to track foraging vultures in the field. Yet, in order to track, vultures need to be trapped and tagged in manner that would ensure their health and normal survival and behavior. GPS telemetry is currently the best tool to track vultures for foraging studies. In a review of recent studies, we highlight the predominance of studies of species from Europe, North America and Southern Africa, and we deplore the lack of knowledge of species from the Tropics. Home ranges vary tremendously between sites, season and species (from a few km² to >300,000 km²) but also depending on the analysis method used. Daily distances travelled are more repeatable between species, with values ranging between 30 and 40 km. Yet the way that carrion distribution can affect scavenger distribution and foraging behavior is still poorly understood.

Death detector: Using vultures as sentinels to detect carcasses by combining bio‐logging and machine learning

Article

Full-text available

Nov 2024
J APPL ECOL

Bio‐logging technologies allow scientists to remotely monitor animal behaviour and the environment. In this study, we used the combination of natural abilities of African white‐backed vultures Gyps africanus and state‐of‐the‐art bio‐logging technology for detecting and locating carcasses in a vast landscape. We used data from two captive and 27 wild vultures to create a reference data set for the training of a support vector machine to distinguish between six behaviour classes based on acceleration data. Next, we combined the classified behaviour of the initial 27 and 7 additional vultures with GPS data and used the ‘Density‐Based Spatial Clustering of Applications with Noise’ algorithm to cluster all GPS data to get a position of potential feeding locations. Finally, we used the clustered data set to train a Random Forest algorithm to distinguish between clusters with and without a carcass. The behaviour classifier was trained on 14,682 samples for all behaviour classes, which were classified with a high performance (overall precision: 0.95, recall: 0.89). This enabled a ground team to examine 1900 clusters between May 2022 and March 2023 in the field, 580 linked to a carcass and 1320 without a carcass. The cluster classifier trained on this data set was able to correctly distinguish between carcass and no carcass clusters with high performance (overall precision: 0.92, recall: 0.89). Synthesis and applications. We showed that a carcass detection system using vultures, loggers and artificial intelligence (AI) can be used to monitor the mortality of numerous species in a vast landscape. This method has broad applications, such as studying the feeding ecology of vultures, detecting and monitoring of disease outbreaks, environmental poisoning or illegal killing of wildlife. Similar to vultures and carcasses, our methodological framework can be applied to other species to locate their respective food resources. It could also be applied to other types of resources like temporary water sources, roosting sites and to other behaviours such as marking to locate marking sites.

A wrap-around movement path randomization method to distinguish social and spatial drivers of animal interactions

Article

Full-text available

Sep 2024
PHILOS T R SOC B

Studying the spatial–social interface requires tools that distinguish between social and spatial drivers of interactions. Testing hypotheses about the factors determining animal interactions often involves comparing observed interactions with reference or ‘null’ models. One approach to accounting for spatial drivers of social interactions in reference models is randomizing animal movement paths to decouple spatial and social phenotypes while maintaining environmental effects on movements. Here, we update a reference model that detects social attraction above the effect of spatial constraints. We explore the use of our ‘wrap-around’ method and compare its performance to the previous approach using agent-based simulations. The wrap-around method provides reference models that are more similar to the original tracking data, while still distinguishing between social and spatial drivers. Furthermore, the wrap-around approach results in fewer false-positives than its predecessor, especially when animals do not return to one place each night but change movement foci, either locally or directionally. Finally, we show that interactions among GPS-tracked griffon vultures (Gyps fulvus) emerge from social attraction rather than from spatial constraints on their movements. We conclude by highlighting the biological situations in which the updated method might be most suitable for testing hypotheses about the underlying causes of social interactions. This article is part of the theme issue ‘The spatial–social interface: a theoretical and empirical integration’.

A wrap-around movement path randomization method to distinguish social and spatial drivers of animal interactions

Preprint

Full-text available

May 2024

Studying the spatial-social interface requires tools that distinguish between social and spatial drivers of interactions. Testing hypotheses regarding the factors determining animal interactions often involves comparing observed interactions with reference or ’null’ models. One approach to accounting for spatial drivers of social interactions in reference models is randomizing animal movement paths to decouple spatial and social phenotypes while maintaining environmental effects on movements. Here, we update a reference model that detects social attraction above the effect of spatial constraints. We explore the utility of our 'wrap-around' method and compare its performance to the previous approach using agent-based simulations. The wrap-around method provides reference models that are more similar to the original tracking data, while still distinguishing between social and spatial drivers. Furthermore, the wrap-around approach results in fewer false-positives than its predecessor, especially when animals do not return to one place each night but change movement foci, either locally or directionally. Finally, we show that interactions among GPS-tracked griffon vultures (Gyps fulvus) emerge from social attraction rather than from spatial constraints on their movements. We conclude by highlighting the biological situations in which the updated method might be most suitable for testing hypotheses about the underlying causes of social interactions.

The use of social information in vulture flight decisions

Article

Full-text available

Mar 2024

Animals rely on a balance of personal and social information to decide when and where to move next in order to access a desired resource. The benefits from cueing on conspecifics to reduce uncertainty about resource availability can be rapidly overcome by the risks of within-group competition, often exacerbated toward low-ranked individuals. Being obligate soarers, relying on thermal updraughts to search for carcasses around which competition can be fierce, vultures represent ideal models to investigate the balance between personal and social information during foraging movements. Linking dominance hierarchy, social affinities and meteorological conditions to movement decisions of eight captive vultures, Gyps spp., released for free flights in natural soaring conditions, we found that they relied on social information (i.e. other vultures using/having used the thermals) to find the next thermal updraught, especially in unfavourable flight conditions. Low-ranked individuals were more likely to disregard social cues when deciding where to go next, possibly to minimize the competitive risk of social aggregation. These results exemplify the architecture of decision-making during flight in social birds. It suggests that the environmental context, the context of risk and the social system as a whole calibrate the balance between personal and social information use.

Observations on the Foraging Behaviour and Activity Patterns of Globally Endangered Egyptian Vulture, Neophron Percnopterus in Uttar Pradesh

Article

Full-text available

Dec 2023

The basic concern for species survival is the food availability; consequently, it is a fundamental component to identify the habitat preference, population density and endurance of the species. In the present study, our goals were to assess the foraging behaviour and other activity patterns of Egyptian Vulture. The focal animal sampling method described by Altman (1974) was followed for recording the time-budget and activity pattern of Egyptian Vulture during feeding. Data on various activities were recorded at the prominent feeding site in Unnao from January 2016-January 2019.Various foraging activities were followed keenly throughout the day. Following the techniques adopted by Kambale [39], the day was divided into three-time frames to observe various behavioral activities of the Egyptian Vulture throughout the day.17 different types of behavioural activities were observed at the feeding site, of which maximum time spent in performing sunning and least time spent in Parental care. Egyptian Vultures spent maximum time for foraging during afternoon followed by morning and evening hours. The major factor in predicting the feeding time preference during a day is the predictability of the food supply. The study will assist the conservation and management of a healthy Egyptian Vulture population. The study recommends the protection of the legal slaughterhouses and dumping sites in the region where Egyptian Vultures still exist and establishment of 'Vulture restaurants' for providing the safe and healthy food for vultures.

Heterospecific coprophagy of Coragyps atratus (Cathartiformes: Cathartidae) with Jabiru mycteria (Ciconiiformes: Ciconiidae) in Curvelo, Minas Gerais, Brazil

Article

Oct 2023

Heterocoprophagy is the behavior of consuming feces of another species. Despite being documented, there are no records of this interaction between wild birds. We report the first record of heterocoprophagy between C. atratus and M. jabiru, which occurred in Curvelo, Minas Gerais. We believe that the present record is the first case of heterospecific coprophagy between two wild birds and we encourage researchers to report this type of interaction to improve knowledge and understanding of the natural history of these birds.

Social situations differ in their contribution to population‐level social structure in griffon vultures

Article

Full-text available

Jun 2023

Social relationships among animals emerge from interactions in multiple ecological and social situations. However, we seldom ask how each situation contributes to the global structure of a population, and whether different situations contribute different information about social relationships and the position of individuals within the social fabric. Griffon vultures (Gyps fulvus) interact socially in multiple situations, including communal roosting, joint flights, and co-feeding. These social interactions can influence population-level outcomes, such as disease transmission and information sharing that determine survival and response to changes. We examined the unique contribution of each social and ecological situation to the social structure of the population and individuals' positions within the overall social network using high-resolution GPS tracking. We found that the number of individuals each vulture interacted with (degree) was best predicted by diurnal interactions-both during flights and on the ground (such as when feeding). However, the strength of social bonds, that is, the number of interactions an individual had (strength), was best predicted by interactions on the ground-both during the day (e.g., while feeding) and at night (e.g., while roosting) but not by interactions while flying. Thus, social situations differ in their impact on the relationships that individuals form. By incorporating the ecological situations in which social interactions occur we gain a more complete view of how social relationships are formed and which situations are important for different types of interactions.

Social situations differ in their contribution to population-level social structure in griffon vultures

Preprint

Apr 2022

Animal social relationships emerge from interactions in multiple ecological situations. However, we seldom ask how each situation contributes to the structure of a population or to the social position of individuals. Griffon vultures interact in multiple situations, including when roosting, flying, and feeding. These social interactions can influence population-level outcomes such as disease transmission and information sharing. We examined the contribution of each ecological situation to the social structure of the population and to individuals’ social positions using GPS-tracking. We found that the number of individuals each vulture interacted with was best predicted by diurnal interactions. However, the strength of social bonds was best predicted by interactions on the ground – both during the day and at night but not by interactions while flying. Thus, social situations differ in their impact on the relationships that individuals form. Given the conservation importance of vultures, these findings can inform wildlife management actions.

Identifying priority locations to protect a wide-ranging Endangered Species

Article

Full-text available

Jan 2023
BIOL CONSERV

1.Medium and large scavengers often move long distances to locate sufficient foraging areas, often including buffer zones of protected areas, putting them at considerable risk from geographically dispersed threats. 2.Vultures are declining worldwide with poisoning being the greatest threat in Africa. Using a novel capture-recapture model applied to carcasses found by 51 GPS tracked vultures, we estimated the exposure, threat, and risk of poisoning to vultures in southern Tanzania. Exposure to poisoning was defined as the areas that vultures use and where carcasses are likely to be found by a given individual. We used a human footprint map as a proxy for threat, identifying locations where poisoning was possible. Risk of poisoning was determined as areas with an overlap of exposure and threat. 3.We found that locations with the greatest risk of poisoning were within 20 km of protected areas. Although most high-risk areas we identified fell within this buffer, our risk assessment method identified additional hot-spots including some high-risk areas that fell outside nearby buffers. 4.We found that our risk assessment allowed us to identify more localised, high-risk areas that cover a much smaller total area. This gives more precise insight into where conservation management should be prioritised and limited resources should be focused.

Rewilding processes shape the use of Mediterranean landscapes by an avian top scavenger

Article

Full-text available

Feb 2020

The Mediterranean biome has seen a great decline in its rural population. This trend has been followed by an abandonment of agricultural and livestock practices, which has provided an opportunity for rewilding to take place. Rewilding processes can modify the availability of carrion resources for avian obligate scavengers and reduce accessible open areas due to the increase of shrub and forest. We examined how changes in landscape configuration in the past five decades (1956–2011) mediate the foraging behaviour of griffon vultures. Particularly, we examined whether vultures use those areas under natural succession and with a high availability of wild ungulate carcasses. We used GPS information yielded by 30 adult griffon vultures exploiting large regions of southern Spain. We determined (a) habitat use considering land uses and food availability and (b) how tracked individuals responded to areas in different stages of rewilding. Our results showed that vultures preferentially used Mediterranean scrublands, woodlands and the agroforest Mediterranean ecosystem called dehesa, as well as areas with high food resources, namely wild ungulates in winter and a mixture of wild ungulates and livestock in summer. Due to a higher abundance of wild ungulates, vultures forage preferentially in areas with low levels of rewilding, either for being in the first stages of natural succession or for not having experienced further rewilding since the middle of the last century. Rewilding processes are expected to continue in the future affecting the scavenger guild structure and function deeply. Improved management will be essential to preserve ecological processes, ecosystem services and populations of endangered species.

Home Range, Movement and Activity Pattern of Six Threatened Vulture Species using Satellite Telemetry in Saurashtra Landscape, Gujarat

Article

Full-text available

Oct 2022

The information on the ranging behaviour and migration pattern of vultures is of critical conservation importance. Vultures’ range over vast areas in human-dominated landscapes where anthropogenic activities may influence their long-term survival. This paper uses the satellite telemetry of 11 individuals of six vulture species to assess their home ranges and seasonal movement patterns. The study aimed to find daily and monthly distances covered by vultures, their home range size, and the influence of breeding season on resource utilisation and activity rates. A total of 114,820 locations were collected between October 2020 and November 2021. The results indicate that the size of the core area is smaller during the breeding season of the resident species, such as the Indian vulture (Gyps indicus), white-rumped vulture (Gyps bengalensis), and red-headed vulture (Sarcogyps calvus) than the non-breeding season. vulture’s daily and monthly movement (mean) also decreased in the breeding season. The annual home range and core areas, calculated as 95% and 50%Utilisation Distribution differed between breeding and non-breeding seasons. The migratory vultures moved significantly longer distances across days and months than the resident species. Their annual migration patterns also differed with respect to time and migration routes.

Hidden effects of high numbers of tourists in protected areas: displacement of foraging top scavengers

Article

Jul 2022

Protected areas in southern Europe are important for the conservation of large avian scavengers. However, the effects an increasing number of visitors may have on the scavengers’ patterns of movement are unknown. Here, we took advantage of data collected from seven GPS‐tagged adult Griffon Vultures Gyps fulvus breeding in the Bardenas Reales Natural Park in northern Spain to determine if foraging birds moved to more remote areas on the days when the number of visitors increased. We found that while the number of visitors did appear to affect movement patterns, this had a smaller effect size than the mean temperature of the day. Additionally, males moved further than females. If the number of visitors to natural areas continues to increase, local exclusions of Griffon Vultures may become more common, so further research is needed to address the potential consequences for the scavenger population and ecosystem functions and services they provide.

Are white-rumped vultures (Gyps bengalensis) scavengers or predators at a vulture safe feeding site of Nepal?

Article

Full-text available

Jul 2022

Gautan R, Baral N, Sharma HP. 2022. Are white-rumped vultures (Gyps bengalensis) scavengers or predators at a vulture safe feeding site of Nepal?. Biodiversitas 23: 3808-3812. Establishing safe feeding sites has been promoted as a strategy to conserve wild vultures following the population crash in South Asia due to the contamination of natural food by veterinary diclofenac. Several feeding sites have been established in the region, including Nepal and it is important to evaluate their effectiveness. One aspect that is not clear yet is whether such safe feeding sites change the behaviors of wild vultures in South Asia. Here, we report incidents of White-rumped Vultures Gyps bengalensis attacking live animals at the Vulture Safe Feeding Site in Ghachok village in central Nepal. Even though a carcass was available nearby to feed upon, three White-rumped Vultures attacked an adult cow and a calf at the feeding site. The vultures' attack served as an ancillary cause of the calf's death in this case. These two incidents of vultures' attacking live animals at the safe feeding site may allude to changing behaviors and cast doubt on their status of being classified as an obligate scavengers. The findings suggest alteration of vulture behaviors at the safe feeding site. Further research is needed to test the hypothesis of vulture behavior change.

Sighting of critically-endangered White-rumped vulture Gyps bengalensis (J.F. Gmelin, 1788) in Krusadai Island, Rameswaram, India

Article

Jan 2022

Vidya Padmakumar

The most adept scavengers in ecology, vultures, are on the edge of collapse. The Indian subcontinent has nine species of vultures, five of which belong to the genus Gyps and the others are the least impact. The White-rumped vulture Gyps bengalensis, Long-billed vulture Gyps indicus, and Slender-billed Gyps tenuirostris vultures were originally and until lately the most numerous variety in India. Nevertheless, during the last ten, the abundance of these vultures has plummeted across the country. The current study reports Gyps bengalensis for the first time sighted in cauldrons on the desolate Krusadai Island, located south of Pamban Island in the Gulf of Mannar. The finding of the cauldron highlights the need for long-term research into the region to locate nesting places and aid conservation and management.

Vultures feeding on the dark side: current sanitary regulations may not be enough

Article

Jun 2022

It is widely acknowledged that the conservation of vultures, a group of birds threatened worldwide, requires the management of safe, high-quality human subsidies, free of potentially harmful toxic compounds. Additionally, in Europe, the supply of livestock carcasses is subject to current sanitary regulations. It is largely unknown how vultures use sources of food of different abundance, predictability, or different legal status and how individual features shape these preferences. To answer these questions, we took advantage of information yielded by 35 GPS-tagged adult Eurasian Griffon Vultures Gyps fulvus living in a region of northern Spain, which hosts one of the most important European populations. Our results indicated that vultures preferably used predictable feeding sites, such as carcass dumping sites, intensive farms and landfills which together account for the 62% of the observed feeding sites. Less than 10% of all observed sites had permission of authorities for the disposal of the carcasses. Interestingly, sites with large accumulations of carcasses were less used that those with intermediate amounts of food probably because of high intraspecific competition. In addition, sex and breeding status also played a role with males and breeding birds being more prone to visit the studied intensively managed feeding places. This vulture population is heavily dependent on food sources which are not under legal control where the birds could be at risk of intoxication and pathogen acquisition. Hence, current legal scenario allowing farmers to abandon carcasses in their exploitations seems insufficient. The future of vultures in highly anthropized regions is uncertain if interdictory regulations on the abandonment of carcasses of intensive livestock are applied. Additionally, conservation scenarios based on food subsidization must consider the effects of environmental and individual variability. We need science-based strategies ensuring the long-term viability of avian scavenger populations within a scenario of anthropized landscapes and livestock farming intensification.

Dynamique, régulation et viabilité des populations restaurées : le cas du Vautour moine (Aegypius monachus) en France

Thesis

Full-text available

Oct 2020

Typhaine Rousteau

Les réintroductions sont des opérations de conservation visant la restauration des populations d’espèces menacées. L’analyse des facteurs influençant le succès ou les échecs des programmes de réintroduction est cruciale pour comprendre les processus d’établissement d’une nouvelle population; identifier les potentiels facteurs qui pourraient limiter la croissance de cette population; et mesurer si l’objectif majeur de restaurer une population viable sur le long terme est atteint. Dans cette thèse, j’ai utilisé des approches démographiques et spatiales, incluant des estimations de survies et de mouvements par modèles CMR multi évènement, pour améliorer la compréhension de la dynamique spatio-temporelle des trois populations de vautours moines réintroduites en France (une dans les Grands-Causses et deux dans les Préalpes) et discuter du succès de ces programmes de réintroduction à différentes échelles populationnelles et temporelles. Nous avons utilisé les estimations démographiques obtenues et les proxys de capacités limites du milieu à chaque niveau populationnel, pour élaborer des modèles de dynamique et de viabilité des populations. Ceux-ci nous ont permis de quantifier les tendances/les taux de croissance de chaque population et de la (méta)population française dans son ensemble, ainsi que d’étudier leur probabilité d’extinction sur le long terme.

Effects of habitat, season and flood on corvid scavenging dynamics in Central Australia

Article

Aug 2022

Carrion is an ubiquitous resource that drives the dynamics of scavenger populations and shapes the structure and composition of their communities. Corvids (Family: Corvidae) are among the most common scavengers globally, facilitating carcass discovery by other species and contributing to carcass biomass removal. Here, we examine how environmental factors influence corvid scavenging dynamics in an arid region of Central Australia. Specifically, we investigate how habitat, season and a major flood event affect corvid discovery and visitation time, and group size around carcass sites. To do so, we used data collected from camera traps monitoring 80 experimentally positioned red kangaroo (Osphranter rufus) carcasses stratified across closed and open habitats, spring and winter seasons, and before and after a flood event. Corvids took longer to discover carcasses in closed compared to open habitats, but habitat did not affect how long corvids spent visiting carcasses, or corvid group size. Corvids discovered carcasses faster in winter compared to spring and in post‐flood compared with the pre‐flood periods, and season and flood interacted to influence both corvid visitation time and group size. Our results reflect a complex interplay between temperature, the extreme boom and bust cyclicity of the study region and changing corvid activity and abundance in the local study area. We identify environmental factors as key determinants of corvid scavenging dynamics and provide the first detailed description of scavenging by corvids in the arid zone of Australia.

BIOLOGÍA Y CONSERVACIÓN DE LAS POBLACIONES DE BUITRE NEGRO (AEGYPIUS MONACHUS) EN EXTREMADURA

Thesis

Full-text available

Jul 2005

Emilio Costillo Borrego

CONCLUSIONES 1ª Las poblaciones de Buitre Negro (Aegypius monachus) de Extremadura son de gran interés no sólo por su número sino por la presencia de colonias de tipologías muy diversas, lo que se manifestó en el comportamiento particular de las mismas en los distintos aspectos abordados en este estudio. 2ª A pesar de estas diferencias entre las distintas colonias, en todos los casos la elección del lugar de nidificación se encontró principalmente asociada a la pendiente y al aislamiento frente a la actividad humana, además a la disponibilidad de un sustrato adecuado y con un clima no extremo. No obstante a nivel local estas preferencias estuvieron matizadas en cada una de las colonias de acuerdo con las particularidades de las mismas. 3ª El éxito reproductor de la especie estuvo del mismo modo asociado a factores de diversa índole tanto en el área del nido como en el área de forrajeo. De nuevo el elemento antrópico fue importante ya que fue el único factor que se asoció con el fracaso reproductor globalmente en Extremadura. Esto señala la generalidad de las molestias humanas como uno de los factores que incide negativamente sobre el proceso reproductor de estas aves en todas las colonias extremeñas. A nivel local también se hallaron asociaciones similares entre factores fisiográficos, climáticos y antrópicos del área del nido y de forrajeo con el éxito reproductor en cada colonia. 4ª En cuanto a la selección individual del espacio, los adultos de Buitre Negro mostraron áreas de campeo muy amplias, lo que les permite explotar carroñas alejadas de las colonias. En este aspecto existen diferencias notables en cuanto a las áreas de campeo y los desplazamientos de los distintos individuos adultos marcados. Estos valores fueron aún más extensos en los individuos no reproductores. Los desplazamientos se vieron influidos también por la meteorología y la época del año. 5ª Los bosques y dehesas adquirieron gran importancia para las aves a la hora de establecer sus áreas de campeo, en especial en las áreas centrales del área de campeo que se corresponde con las zonas más utilizadas por el ejemplar. En las zonas de alimentación junto a la importancia del medios arbolados donde destaca la dehesa, también tuvieron relevancia áreas desarboladas como los pastizales. 6ª Los jóvenes mostraron un patrón de comportamiento en cuanto al uso del espacio diferente a los adultos con áreas de campeo más grandes. Estas diferencias también se hallaron entre los propios individuos juveniles. Las hembras llevaron a cabo mayores desplazamientos y se establecieron fuera de la colonia, a gran distancias y durante un periodo de tiempo considerable. Los machos por el contrario permanecieron errantes por la colonia de origen y mostraron un patrón diferente entre ellos, pues uno llevó a cabo movimientos exploratorios de corta duración temporal mientras que el otro permaneció prácticamente durante todo el seguimiento en la colonia de Sierra de San Pedro. 7 ª En la dispersión juvenil se hallaron dos fases. En una primera fase o periodo de dependencia los individuos permanecieron en las cercanías del nido, y aunque llevaron a cabo grades desplazamientos siempre fueron de corta duración volviendo de nuevo al nido. En una segunda fase o periodo de independencia se observan mayores diferencias entre las aves, que ya no se hallaban ligadas al nido. El momento de la independencia de los pollos tuvo lugar a finales de noviembre. 8ª A pesar de las diferencias existentes en todos los casos, hubo dos hechos comunes en este patrón de dispersión. Por un lado las aves muestraron una marcada tendencia filopátrica y por otro la presencia de congéneres determina una fuerte atracción hacia los lugares ocupados por estos en sus salidas fuera de la colonia; se visitaron así otras colonias y dormideros de la especie. Los datos mostraron que para los juveniles de la colonia de la Sierra de San Pedro, existieron al menos dos áreas preferenciales a la hora de realizar movimientos exploratorios fuera de la misma. Una de ellas fue el río Tajo y las sierras de Portugal más próximas a la Sierra de San Pedro y otra se situó en el centro de la provincia de Salamanca. 9ª En todas las colonias extremeñas, el Buitre Negro basó su alimentación en el consumo de cadáveres de Ovejas. No obstante, se apreciaron importantes diferencias en las presas con las que los buitres negros completaron su dieta en cada colonia. En Sierra de Gata lo hicieron con Aves de granjas intensivas y Suidos, mientras que en Sierra de San Pedro y Granadilla fueron Suidos y Cérvidos. Se encontró además que la situación no fue fija dentro de cada colonia, sino que pueden existir diferencias en la dieta entre las distintas subcolonias o zonas que componen una colonia. 10ª Estas diferencias en la dieta se encontraron también cuando se compararon con otras poblaciones de la Península Ibérica fruto de la distinta disponibilidad de alimento en cada una de ellas. A grandes rasgos se pudieron distinguir dos tipos de colonias según su dieta, una basada en la ganadería y otras en animales salvajes, cérvidos y lagomorfos. Estos últimos fueron una presa básica en Extremadura en los años 70, antes de la caída poblacional del conejo. 11ª Se reveló de esta forma la gran plasticidad trófica de esta especie, capaz tanto de aprovechar nuevos recursos (como aves de granjas intensivas) como de responder a drásticos cambios en su ecosistema (disminución de las poblaciones de conejo, aumento de la ganadería de ovino y porcino, auge de la caza mayor, etc.). 12ª Estas particularidades de cada colonia señalan la importancia de considerarlas a la hora de diseñar estrategias para la conservación de la especie. De este modo el conocimiento de la disponibilidad de recursos en el entorno de cada colonia, deben ser tomadas en cuenta para la conservación del Buitre Negro, que en ocasiones basa su alimentación en recursos altamente humanizados susceptibles por tanto de sufrir importantes cambios en su disponibilidad para la especie.

Understanding continent-wide variation in vulture ranging behavior to assess feasibility of Vulture Safe Zones in Africa: Challenges and possibilities

Article

Full-text available

Apr 2022
BIOL CONSERV

Protected areas are intended as tools in reducing threats to wildlife and preserving habitat for their long-term population persistence. Studies on ranging behavior provide insight into the utility of protected areas. Vultures are one of the fastest declining groups of birds globally and are popular subjects for telemetry studies, but continent-wide studies are lacking. To address how vultures use space and identify the areas and location of possible vulture safe zones, we assess home range size and their overlap with protected areas by species, age, breeding status, season, and region using a large continent-wide telemetry datasets that includes 163 individuals of three species of threatened Gyps vulture. Immature vultures of all three species had larger home ranges and used a greater area outside of protected areas than breeding and non-breeding adults. Cape vultures had the smallest home range sizes and the lowest level of overlap with protected areas. Rüppell's vultures had larger home range sizes in the wet season, when poisoning may increase due to human-carnivore conflict. Overall, our study suggests challenges for the creation of Vulture Safe Zones to protect African vultures. At a minimum, areas of 24,000 km² would be needed to protect the entire range of an adult African White-backed vulture and areas of more than 75,000 km² for wider-ranging Rüppell's vultures. Vulture Safe Zones in Africa would generally need to be larger than existing protected areas, which would require widespread conservation activities outside of protected areas to be successful.

Distributed Adaptations: Can a Species Be Adapted While No Single Individual Carries the Adaptation?

Article

Full-text available

Feb 2022

Species’ adaptation to their environments occurs via a range of mechanisms of adaptation. These include genetic adaptations as well as non-traditional inheritance mechanisms such as learned behaviors, niche construction, epigenetics, horizontal gene transfer, and alteration of the composition of a host’s associated microbiome. We propose to supplement these with another modality of eco-evolutionary dynamics: cases in which adaptation to the environment occurs via what may be called a “distributed adaptation,” in which the adaptation is not conferred via something carried by an individual of the adapted species (as with genes, behavior, or associated microbes), but by some structural or compositional aspect of the population. Put differently, the adaptively relevant information cannot be reduced to information possessed by a single individual, whether genetic or otherwise. Rather, the adaptively relevant information is distributed, and is found strictly at the population level. While human culture is presumably such a case, as may be cases found in social insects, we want to suggest that there are other cases that belong to this category and to explore its evolutionary implications. In particular, we discuss the factors that affect whether adaptive information is stored in a distributed way, to what degree, and what kinds of adaptive information are most likely to be found in this modality of adaptation.

Evidence of widespread declines in Kenya's raptor populations over a 40-year period

Article

Feb 2022
BIOL CONSERV

Kenya's wildlife has been declining substantially for decades, due to rapid human population growth and its associated impacts on natural habitats. Predators and scavengers are particularly sensitive to anthropogenic pressures, and their changing status has corresponding impacts on the ecosystem services they provide. To estimate rates of change in Kenya's raptor populations we compared linear encounter rates (individuals 100 km − 1) recorded during road surveys conducted in 1970-1977 and 2003-2020. Encounter rates for 19 out of 22 species examined had fallen, by a median of 70% among those showing a significant or near-significant change. No species had increased significantly. Declines had occurred among all vulture and large eagle species, and were especially pronounced among once-common small and medium-sized raptors. Our findings demonstrate the importance of protected areas (PAs) for Kenya's remaining raptor populations. The median encounter rate for vultures and large eagles had dropped by 23% within PAs and by 76% in unprotected areas. Smaller species showed divergent trends in relation to PA status, their median encounter rate increasing by 104% within PAs while declining by 85% elsewhere. Based on projected declines over three generation lengths, 45% of the species examined would qualify as nationally Endangered or Critically Endangered. Key threats include electrocution/collision with energy infrastructure, deliberate and incidental poisoning, and impacts associated with habitat degradation. Kenya's raptor declines could be reversed through enhanced management of PAs, mitigation of specific threats and the implementation of species recovery plans; all requiring steadfast government commitment and close collaboration with conservation stakeholders.

Modeling breeding habitat suitability of Griffon vultures (Gyps fulvus) in Bulgaria and conservation planning

Article

Full-text available

Jan 2022
NORTH-WEST J ZOOL

The narrow ecological niche and the vulnerability of the griffon vulture in terms of its habitat and trophic requirements make it a good model species for assessing the state of agro-pastoral systems. The environmental niche of the species was studied in Bulgaria using a set of 109 cases of griffon vulture presence observations in breeding habitat and a maximum-entropy (MaxEnt) modeling approach. MaxEnt can generate a model based on relatively low number of presence locations and is therefore a powerful tool for modeling species distribution. We employed a set of bioclimatic and environmental variables to determine species' optimal distribution. According to our results, griffon vulture's optimal habitats included areas with a slope over 40 0 , which are advantageous for the breeding of the species as they often outline rocky habitats. The griffon vulture environmental niche model underlined the significance of the open landscapes that are essential for the species' foraging, as well as territories with higher mean temperature, low precipitation and high density of livestock. The suitability threshold of the model equal to 0.0738 and we estimated that 0.69% (769 km 2) of Bulgaria is optimal for the breeding of the species and that 2.8% (3085 km 2) is of high suitability for the griffon vulture. The results of the current survey aim to provide an important background for the management and conservation of the griffon vulture in Bulgaria. Such estimates are essential whenever investment plans, conservation programs or other management interventions are considered in the territories neighbouring or/and within the range of the griffon vulture.

Effect of WeChat interaction on brand evaluation: A moderated mediation model of para-social interaction and affiliative tendency

Article

Jan 2022
J Retailing Consum Serv

As an indispensable platform for the interaction and relationship marketing in China, the systematic discussion about the impact of WeChat interaction on brand evaluation is still not well understood. Based on para-social interaction theory, this study examined the relationships between WeChat interaction, para-social interaction, brand evaluation and affiliative tendency, utilizing valid survey data of 216 Chinese users of WeChat. The findings of this study revealed that there is a positive relationship between WeChat interaction and brand evaluation, and para-social interaction plays a mediation role for its virtual intimacy. Compared to the high affiliative tendency, low affiliative tendency enhances the positive effect of para-social interaction on brand evaluation and the mediating path. Through detailed analyses, the conclusions identified para-social interaction as a mediator and affiliative tendency as a moderator in the relationship between WeChat interaction and brand evaluation. On the basis of these results, the practical implications for enterprises are discussed.

Anthropogenic Drivers Leading to Population Decline and Genetic Preservation of the Eurasian Griffon Vulture (Gyps fulvus)

Article

Full-text available

Oct 2021

Human activities are having increasingly devastating effects on the health of marine and terrestrial ecosystems. Studying the adaptive responses of animal species to changes in their habitat can be useful in mitigating this impact. Vultures represent one of the most virtuous examples of adaptation to human-induced environmental changes. Once dependent on wild ungulate populations, these birds have adapted to the epochal change resulting from the birth of agriculture and livestock domestication, maintaining their essential role as ecological scavengers. In this review, we retrace the main splitting events characterising the vultures’ evolution, with particular emphasis on the Eurasian griffon Gyps fulvus. We summarise the main ecological and behavioural traits of this species, highlighting its vulnerability to elements introduced into the habitat by humans. We collected the genetic information available to date, underlining their importance for improving the management of this species, as an essential tool to support restocking practices and to protect the genetic integrity of G. fulvus. Finally, we examine the difficulties in implementing a coordination system that allows genetic information to be effectively transferred into management programs. Until a linking network is established between scientific research and management practices, the risk of losing important wildlife resources remains high.

Space Use and Time Budget in Two Populations of Griffon Vultures in Contrasting Landscapes

Article

Full-text available

Aug 2021

Animals' movements integrate multiple factors, such as motion and navigational abilities, the motivational and internal states of the individuals, and environmental conditions. We studied Griffon Vultures (Gyps fulvus) from two populations (Causses and Pyrenees, France) to determine whether they adapt their movements (foraging and home range) and their time/energy budgets to the local environmental conditions and their breeding status. We found that Caussean vultures spent 35% more time flying per day and 37% more time per flight than Pyrenean birds, landed twice as often to eat, and were 67% more active while on the ground. The distance vultures travelled in the Causses, and to a lesser extent in the Pyrenees, appeared to be influenced by the availability of thermals. Our results suggest that the breeding status of the individual, the seasonality of the availability of food resources and its predictability, and meteorological conditions can influence movements and home ranging behavior. Both internal and external factors also affect the size and shape of home ranges. However, the fact that the vultures we tracked in the Causses were breeding birds whereas most of those in the Pyrenees were nonbreeders precluded us from disentangling the effects of breeding constraints and environment.

Придвижване и индивидуален участък на белоглавия лешояд (Gyps fulvus Hablizl, 1783) в България

Thesis

Full-text available

Jan 2020

Volen Arkumarev

Animal movements and bird migration have always fascinated humans (Holyoak et al. 2008). With the fast technology advancement in the past 20 years new systems and methods were developed allowing animals to be tracked for longer periods and significant amount of data to be collected, stored and analysed (Cooke et al. 2004, Cagnacci et al. 2010). Vultures are obligate scavengers which consume up to 90% of the carcasses in some ecosystems providing significant ecosystem services. By efficiently disposing the carcasses they prevent the spread of diseases and save costs from transportation and incineration of animal carcasses (Houston 1986, Pain et al. 2003). However, vulture populations are experiencing dramatic declines worldwide and their conservation is a priority in many areas (Botha et al. 2017). Due to their conservation status and role in the ecosystems more studies on vulture movements and ecology are needed to inform efficient conservation strategies. The recent study was conducted on the autochthonous Griffon Vulture population in the Eastern Rhodopes, Bulgaria. In the period 2016 – 2019 we equipped with solar-powered GSM-GPS and Argos-GPS transmitters adult (n = 10), immature (n = 8) and juvenile (n = 7) Griffon Vultures in order to study their home range, movements, foraging behaviour and migration pattern. The foraging home range of the species was 2958.4 km2 (95% KDE) with core area of 231.6 km2 (50% KDE). Foraging home range size was maximal in summer and minimal in winter (3166.2 km2 and 1327.7 km2 respectively). Adult vultures had significantly smaller core areas compared to immatures (Z = –2.15, p = 0.03). The daily travel distance with all seasons and all individuals pooled was 79.1 ± 64.9 km while displacement was 21.4 ± 20.5 km. The longest daily distance was recorded on 07th May when an immature vulture travelled 364.4 km within the Eastern Rhodopes. Successful breeders travelled longer daily distances than the adults which were not breeding or failed at different stage of their breeding attempt (89.5 ± 71.9 km and 65.7 ± 65.9 km respectively, t = 4.37, p < 0.05). The mean daily distance travelled by the immature vultures was 85 ± 66.06 km while adults travelled 76.82 ± 64.5 km (t = –6.05, p < 0.01). The difference between the two age classes was most prominent during winter and autumn when immatures travelled 45.8 ± 41.7 km and 51 ± 44 km respectively while adults had significantly shorter daily distances 29.9 ± 31.3 km and 36.6 ± 42.8 km (t = –5.37, p < 0.01; t = –5.45, p < 0.01). Griffon Vultures were roosting mostly on cliffs (85.62%, n = 8120), in 14.05% of the cases they were roosting on trees and twice ground roosts were recorded. In the Bulgarian part of the Eastern Rhodopes vultures were roosting on cliffs in 94.6 ± 3.9% of the cases while in the Greek part of the mountain they were roosting mostly on trees – 78.7 ± 24.4%. Our results indicated high variance in the preferences of roosting cliffs according to the season. In autumn and winter vultures were roosting on cliffs with breeding pairs in 80.1 ± 24.2% and 88 ± 24.8% of the cases respectively while this percentage dropped significantly is spring and summer when vultures preferred to roost on cliffs with no breeding pairs (59.4 ± 25.3% and 45.8 ± 24.8%). The recent study showed that 71.5% of the juvenile Griffon Vultures migrate south in their first autumn while only 14% of the immatures started migration and none of the tracked adults. We followed 8 vultures during autumn migration and 5 during the spring migration. Autumn migration started in the period 19th September – 29th October. The average distance travelled on migration was 3602 ± 1137 km, covered for 38 ± 12 days with an average 44 migration speed 100.7 ± 32 km/day. The longest daily distances travelled on migration was 374 km on 30th October when the juvenile vulture 6G crossed the Bosphorus and reached the region of Gerede in Turkey. Spring migration started in the period 22th March – 7th May. The mean distance travelled was 2340 ± 737 km and migration took on average 13 ± 6 days with an average migration speed 176.3 ± 61.8 km/day. Griffon vultures had greater migration speed during the spring than the autumn (t = 2.50, p < 0.05). During autumn migration vultures used different stopover sites along the flyway where they spent between 3 and 50 days. The majority of the stopover sites were in Turkey, one was in Iraq and one on the border area between Iraq and Iran. All vultures followed the Eastern Mediterranean flyway through Turkey and Middle East. The most important bottlenecks for the juvenile and immature Griffon Vultures were the Bosphorus and Iskenderun in Turkey. The main wintering areas were in central and north Saudi Arabia, Israel. One juvenile vulture reached South Sudan which is the first record of the species for the country and one of the southernmost records in Africa. The home range in the wintering areas was 18 933 ± 13 314 km2 (95% KDE) and the size of the core area was 1876 ± 2001.4 km2 (50% KDE). The size of the home range varied among the individuals and the years. In the wintering grounds 78.07% of the area inhabited by the vultures had no vegetation e.g. deserts and rocky mountains. Only 10.05% were covered by sparse vegetation and 8.39% were natural grasslands or arable lands. Griffon Vultures were feeding at natural carcasses found in the wild in the Eastern Rhodopes in 77.4% (n = 1036) of the recorded cases. In winter 56.5% of the feedings were at the vulture feeding stations while in the summer 80.2% of the feeding events were on occasional carcasses found in the wild. The breeding Griffon Vultures were feeding at the vulture restaurants mostly during the pre-breeding and incubation period (54% and 46.6% respectively). During the post-breeding period 81.6% of the feedings were in the wild. Vultures were landing on the feeding stations on average 53.2 h after carcass disposal. In summer and autumn this period was prolonged up to 10 – 12 days. Griffon vultures were feeding in 42.8% of the days in the month. In the summer they were feeding on average once per 1.6 days and in winter once per 4.1 days. One vulture can visit up to 4 feeding locations per day. The recent study revealed that Griffon Vultures travel significantly longer distances in days when they were feeding on carcasses found in the wild compared to days when feeding at vulture restaurants (t = –11.6 p < 0.001). In addition, they have less straight flight and reach lower displacement when feeding on occasional carcasses (t = 5.9, p < 0.001; t = –7.33, p < 0.001). The average daily distances travelled were 80.3 ± 53.3 km in days when vultures were feeding and only 69.8 ± 58.4 km in days when they did not manage to find food. Our model showed that the season and the age of the vultures determine the most their success in finding food. The other factors which showed correlation were the daily travelled distance, daily displacement, temperature, daily precipitation and wind speed. In 47% of the cases (n = 305) vultures were feeding on cattle carcasses in the wild. In 28% sheep or goats were used for food and wild ungulates were found in 11.5% of the cases. Other species consumed by the vultures were fox, jackal, dog, wild boar, hare, horse and donkey. In 4.6% of the cases vultures were feeding at places where offal from slaughter houses was illegally dumped. The most common reason for the death of the animals consumed by the vultures was carnivore attack (60.2%) while in 37.6% of the cases animals died due to natural causes. However, in 2 occasions death was attributed to poaching.

The exposure and contribution of predators and scavengers to humans

Thesis

Full-text available

Mar 2020

Christopher J. O'Bryan

Humans are exerting unparalleled pressures on terrestrial vertebrates through overexploitation and development. The patterns of human destruction on the natural environment are especially prevalent within carnivore distributions because they are subject to not only habitat fragmentation and loss, but they are also perceived as a threat to human societies leading to direct conflict. Although the perceived negative impacts of predators and scavengers dominate policy and individual action towards carnivores, there is a growing body of literature pointing to the potential benefits that predators and scavengers provide within shared landscapes. The overall aim of this thesis is to address key gaps in our knowledge on the exposure and contribution of predators and scavengers to humans and how this information can be used to enhance conservation initiatives. Human pressures cause species extinction. These pressures range from over-hunting and urbanization to other forms of habitat loss such as agricultural development. While human pressures and their threatening processes have been increasingly documented across a range of species and ecosystems, we do not know the extent of intense cumulative human pressures within species’ geographic ranges globally. In Chapter 2, I aim to quantify the exposure of terrestrial vertebrates to intense human pressure, including carnivores. I use the most up-to-date spatial dataset on cumulative human pressure, which takes into account eight pressures known to cause species decline. I find that 85% of the terrestrial vertebrates assessed have more than half of their range exposed to these cumulative pressures, with carnivores having similar exposure. Specifically, carnivores have on average 75% of their ranges overlapping with intense human pressures. This work provides a useful starting point for assessing species at risk of decline, especially for species with limited information on threats. Carnivore declines impact ecosystem stability that can result in negative impacts on human well-being. In Chapter 3, I aim to provide the first review of the benefits provided by predators and scavengers in shared landscapes with humans. I find that predators and scavengers have been shown to reduce zoonotic disease risk, increase agricultural output, and limit species known to cause injury and death to humans. Through the review process, I found considerable gaps in knowledge regarding the potential benefits of predators and scavengers in shared landscapes, and I discuss future avenues of research, its caveats, and opportunities. An important knowledge gap identified during the review was the ecological and human well-being implications of losing apex scavengers. Although there is a great deal of information about the ecological repercussions of losing apex predators, we know relatively little about the role of apex scavengers at regulating lower trophic levels and how this can impact ecosystem health and human well-being. In Chapter 4, I describe the mesoscavenger release hypothesis, the competitive release of mesoscavengers in the absence of apex scavengers. This work sets the foundation for future studies investigating the consequences of apex scavenger decline on ecosystems and human health and provides a springboard for conservation action on imperilled apex scavengers. Another key question asked during the review was the potential role of large carnivores at benefiting humans. Chapters 5-7 focus on addressing this gap. Chapter 5 provides a case study of one of the most widespread large carnivores, leopards (Panthera pardus), at reducing bites and rabies risk from feral dogs in Mumbai, India. I discuss the implications of large carnivores at providing similar services around the world, especially where feral dogs are a considerable human health hazard in peri-urban environments. In Chapter 6 I quantify the predation value of two large carnivore species on an overabundant invasive species, wild pigs (Sus scrofa), known to cause substantial damage to agricultural lands. This chapter offers important information for assessing the benefits of large carnivore conservation on agricultural productivity while accounting for livestock loss. In Chapter 7 I assess the global ramifications of expanding wild pig populations, utilizing information on predicted wild pig densities and data on soil organic carbon (SOC) storage to quantify their relative impacts on SOC vulnerability. I discuss that wild pig control could be promoted through human-induced management and conservation of native predators. These case studies provide a foundation for future work investigating links between natural predation and human well-being through mitigating health hazards and increasing agricultural productivity in shared landscapes. These studies will also deliver conservation practitioners additional information on the consequences of large carnivore recovery. This thesis highlights the state of carnivores in shared landscapes with humans and the potential crucial services they provide. I address key gaps in our knowledge on the exposure and contribution of predators and scavengers to humans and how this information can be used to enhance conservation initiatives

Large home range scavengers support higher rates of carcass removal

Article

Full-text available

Jul 2020
FUNCT ECOL

Vertebrate scavenger communities vary in species composition across the globe. They include a wide array of species with diverse ecological strategies and life histories that support essential ecosystem functions, such as carrion removal. While previous studies have mostly focussed on how community aspects such as species richness and composition affect carrion consumption rates, it remains unclear whether this important function of scavengers is better explained by the dominance of key functional traits or niche complementarity as a result of a diverse functional representation. Here, we test three competitive hypotheses to assess if carrion consumption in vertebrate scavenger communities depends on: (a) the presence of key dominant traits (functional identity hypothesis), (b) functional diversity that promotes niche complementarity (functional diversity hypothesis) or (c) the accumulation of individuals and species, irrespective of their trait representation (functional equivalence). To explore these hypotheses, we used five study areas in Spain and South Africa, which represent a gradient of scavenger biodiversity, that is, ranging from communities dominated by facultative scavengers, such as generalists and meso‐predators, to those including vultures and large carnivores. Within study areas, traits that characterize obligate scavengers or large carnivores (e.g. mean home range, proportion of social foragers) were positively linked to rapid carrion consumption, while the biomass of functional groups including facultative scavengers were either weakly or negatively associated with carrion consumption. When combining all study areas, higher rates of carrion consumption were related to scavenger communities dominated by species with large home ranges (e.g. Gyps vultures), which was found to be a key trait. In contrast, metrics describing functional diversity (functional dispersion) and functional equivalence (species richness and abundance) had lower predictive power in explaining carrion consumption patterns. Our data support the functional identity hypothesis as a better framework for explaining carrion consumption rates than functional diversity or equivalence. Our findings contribute to understanding the mechanisms sustaining ecosystem functioning in vertebrate communities and reinforce the role of obligate scavengers and large carnivores as keystone species in terrestrial ecosystems.

Collapsing towards Extinction? Trade in Birds Carcasses for Traditional Medicine and the Decline of Vulture Population in Katsina State, Nigeria

Article

Full-text available

May 2020

Decline in vulture populations have seriously reported in Nigeria as in other habits around the world. Human pressure from poisoning, hunting and trading for traditional medicine are key factors leading to decline of vulture population in northern Nigeria. This study examines vulture trading for traditional medicine as risk factor for the raptors population decline in Katsina with a view to providing baseline information for reviewing conservation policies in the State and Nigeria at large. The study is a survey research involving questionnaire administration and interview of seventy two stakeholders who were sampled using snowball sampling technique as follows: vulture stall owners (n=58) and abattoir employees (n=10) and traditional healers (n= 4). A total of five locations were surveyed based on the understanding that they possess the most specialized fetish markets and important centres of vulture trading in Katsina State. Percentage and mean were used for data analysis. The study found that trading of vulture is proliferating in the area as more than 50% of the stalls were opened between 2016 and 2019. It also revealed that 80% of the fetish stalls are located outside Katsina town for fear of authorities fighting illicit trade of vulture. Also revealed was that prices of vulture vary in space and depend on relationships with customers: a whole vulture costs N21000 (ca.

55.55) which soars as high as N27000 (ca.

75) outside Katsina town and N30000 (ca. $83) in times of scarcity. This study recommended that there is the need to carry out nationwide comprehensive assessment of trade in avifauna for improving conservation policies and practices in Nigeria. Keywords: carcasses, fetish stalls, traditional medicine, conservation

"An assessment of conservation perspectives of Critically Endangered (CR) vultures in south Asia":

Technical Report

Full-text available

Dec 2015

Bikash Ghimire

A divisional report on conservation perspective of Gyps vultures in South Asia

The mesoscavenger release hypothesis and implications for ecosystem and human well‐being

Article

Full-text available

May 2019
ECOL LETT

Many apex scavenger species, including nearly all obligate scavengers, are in a state of rapid decline and there is growing evidence these declines can drastically alter ecological food webs. Our understanding of how apex scavengers regulate populations of mesoscavengers, those less‐efficient scavengers occupying mid‐trophic levels, is improving; yet, there has been no comprehensive evaluation of the evidence around the competitive release of these species by the loss of apex scavengers. Here we present current evidence that supports the mesoscavenger release hypothesis, the increase in mesoscavengers and increase in carrion in the face of declining apex scavengers. We provide two models of scavenger dynamics to demonstrate that the mesoscavenger release hypothesis is consistent with ecological theory. We further examine the ecological and human well‐being implications of apex scavenger decline, including carrion removal and disease regulation services.

Vultures attacking livestock: A problem of vulture behavioural change or farmers' perception?

Article

Full-text available

Apr 2019

Human-wildlife conflicts are often partly due to biased human perceptions about the real damage caused by wildlife. While Griffon Vultures Gyps fulvus are obligate scavengers, 156 complaint reports about vultures attacking livestock were officially recorded over eight years (2007–2014) in France. We investigated whether this conflict could be explained by a change in vulture behaviour, or by a biased perception by farmers. If vultures became predators, as a consequence of density-dependent processes, we predicted that reports would concern mostly ante-mortem consumption of healthy livestock and would be temporally and spatially correlated to vulture population size and space use. Under the hypothesis of perception bias of farmers, we predicted that reports would concern mostly post-mortem consumption, and would be more numerous in areas where farmers are less familiar with vultures and where herds are less attended by shepherds. The spatio-temporal distribution of reports was not correlated with the vulture’s population trend and was not centred on the core area of vulture home range. In 67% of reports, vultures consumed post-mortem an animal that had died for other reasons. In 18% of reports, vultures consumed ante-mortem an animal that was immobile and close to death before vulture arrival. The fact that 90% of complaining farmers did not own vulture supplementary feeding stations and that 40% of these farms were located outside protected areas (where most education programmes take place) suggests that most farmers had little familiarity or personal knowledge of vultures. There was no shepherd witness present in 95% of the reports. Therefore, the hypothesis of a perception bias due to lack of knowledge was most likely to explain this vulture-livestock conflict rather than the hypothesis of a recent change in vulture feeding behaviour. Environmental education should be better included in conservation programmes and enhanced in areas where vultures are expanding to recolonise their former distribution range.

Decision-making process of biting in lesser moray eel (Gymnothorax minor): the primacy of tactile stimuli

Article

Feb 2025
ICHTHYOL RES

Animal foraging behavior involves a variety of perceptual processes ranging from detection of food presence to consumption. In this study, we investigated the relative importance of visual, olfactory and tactile stimuli in the feeding behavior, specifically in the final foraging stage, known as the food evaluation phase, of the lesser moray eel (Gymnothorax minor), a predatory species that relies primarily on olfaction for foraging. In a controlled tank environment, we exposed the moray to eight different treatment combinations, incorporating variations in visual, olfactory and tactile cues. The results showed that the moray exhibited a higher frequency of biting behavior towards baits with soft tactile properties, while visual and olfactory cues had no significant effect on biting behavior. We concluded that tactile stimuli are of paramount importance in the feeding decision process, even in the lesser moray eel, which typically relies on olfactory and visual cues for detection of food presence and foraging.

Finders' eaters: Increasing bush encroachment may shift carcass detection from diurnal avian to nocturnal mammalian scavengers

Article

Full-text available

Apr 2024

Bush encroachment is increasingly becoming a problem for biodiversity conservation in African savannas. While this invasion by woody vegetation may hamper avian scavengers such as vultures, which primarily search by sight, it may benefit mammalian scavengers that search by smell. This study aimed to examine the ability of nocturnal mammalian and diurnal avian scavengers to locate carcasses at increasing vegetation densities. We successively placed 27 impala ( Aepyceros melampus ) carcasses five days apart in a 2000 ha fenced game camp that offered an extensive range of woody plant densities. Scavenger arrivals and first feedings were recorded with camera traps. The avian scavengers, mainly white‐backed Vultures ( Gyps africanus ), fed exclusively on carcasses during the day, and mammalian scavengers, predominantly brown hyenas ( Parahyena brunnea ), fed solely at night. The two guilds thus competed exploitatively without direct interaction between them. For vultures, the time taken to locate a carcass increased with woody plant density. The mean density of woody plants that avian scavengers located carcasses at was 2188 plants/ha, whereas mammalian scavengers located carcasses at appreciably higher densities of 5156 plants/ha. Resource managers need to understand the synergy between maintaining woody vegetation to benefit nocturnal mammalian scavengers and maintaining open savannas to benefit diurnal avian scavengers.

Nocturnal Feeding in the Eurasian Griffon Vulture Gyps fulvus: A Response to Human Disturbance and the Presence of Mammalian Predators

Article

Apr 2024

Improved African Vulture Optimization Algorithm for Parameter Optimization of Mars Rotorcraft Attitude Controllers

Conference Paper

Dec 2023

Apex scavengers from different European populations converge at threatened savannah landscapes

Article

Full-text available

Feb 2022

Over millennia, human intervention has transformed European habitats mainly through extensive livestock grazing. “Dehesas/Montados” are an Iberian savannah-like ecosystem dominated by oak-trees, bushes and grass species that are subject to agricultural and extensive livestock uses. They are a good example of how large-scale, low intensive transformations can maintain high biodiversity levels as well as socio-economic and cultural values. However, the role that these human-modified habitats can play for individuals or species living beyond their borders is unknown. Here, using a dataset of 106 adult GPS-tagged Eurasian griffon vultures (Gyps fulvus) monitored over seven years, we show how individuals breeding in western European populations from Northern, Central, and Southern Spain, and Southern France made long-range forays (LRFs) of up to 800 km to converge in the threatened Iberian “dehesas” to forage. There, extensive livestock and wild ungulates provide large amounts of carcasses, which are available to scavengers from traditional exploitations and rewilding processes. Our results highlight that maintaining Iberian “dehesas” is critical not only for local biodiversity but also for long-term conservation and the ecosystem services provided by avian scavengers across the continent.

Ecology and Conservation of African White-backed Vultures (Gyps africanus)

Chapter

Jan 2021

African white-backed vultures are a medium-sized vulture with characteristic long-neck and white patch of feathers along their lower back, which is revealed when they are in flight. White-backed vultures are obligate scavengers feeding in social groups across sub-Saharan Africa. Through their soaring flight and communal feeding, this species plays an important role in waste removal and disease control as well as facilitation of mammalian scavengers. As a slow reproducing, long-lived bird, they are particularly susceptible to decline. Anthropogenic threats, particularly poisoning of carrion, are leading to rapid loss of this important species across their range. Only through concerted efforts to prevent poisoning as well as long-term focus on bird-friendly approaches to new electrical infrastructure will this Critically Endangered species persist in the wild.

Animal scavenging on pig cadavers in the Lowveld of South Africa

Article

Aug 2021
FORENSIC SCI INT

Scavenging animals often scatter skeletal remains of forensic interest and leave bite marks. This study aimed to identify scavenging animals in the rural Lowveld of South Africa and to describe their scattering pattern and bite marks on bone. Ten pig cadavers (Sus scrofa domesticus) (40-80 kg) were placed at the Wits Rural Facility, Limpopo, South Africa during the summer and winter seasons. Motion activated cameras recorded the scavenging. Scavenger species were identified and their behaviors, scattering pattern, and bite marks were described. Scavenging was primarily by vultures (hooded, white-backed, and lappet-faced). Marabou stork, slender and banded mongoose, genet, civet, warthog and honey badger also actively scavenged. Vultures began to scavenge the pig cadavers after 18hrs in summer and between 26-28 hours in winter and skeletonized pig cadavers rapidly between 5 - 98 minutes. Skeletonization occurred more rapidly and diffusely in summer while winter cases were densely scattered. Overall the scattered remains were within an area of 157.9m²/1705.5ft² with a radius of 7.09 m/23.3 ft. Vultures cleaned bones thoroughly with very minimal markings - primarily nonspecific scores. The described scattering pattern and bite marks will assist in the recovery and analysis of scavenged remains.

African Vultures Optimization Algorithm: A New Nature-Inspired Metaheuristic Algorithm for Global Optimization Problems

Article

May 2021
COMPUT IND ENG

Metaheuristics play a crucial role in solving optimization problems. The majority of such algorithms are inspired by collective intelligence and foraging of creatures in nature. In this paper, a new metaheuristic is proposed inspired by African vultures' lifestyles. The algorithm is named African Vultures Optimization Algorithm (AVOA) and simulates African vultures’ foraging and navigation behaviors. To evaluate the performance of AVOA, it is first tested on 36 standard benchmark functions. A comparative study is conducted that demonstrates the superiority of the proposed algorithm compared to several existing algorithms. To showcase the applicability of the AVOA and its black box nature, it is employed to find optimal solutions for eleven engineering design problems. Various experiments show that the AVOA performs better than the comparative algorithms in most engineering case studies. As the experiment results, the AVOA algorithm in 30 benchmarks out of 36 benchmarks has achieved better results than the optimizer algorithms and has a significant and better performance on the majority of engineering problems. Wilcoxon rank-sum test has been used for statistical evaluation and indicates the significant superiority of the AVOA algorithm at a 95% confidence interval.

The challenge of detecting prey: Private and social information use in predatory bats

Article

Full-text available

Sep 2019
FUNCT ECOL

In the evolutionary arms race between predators and their prey, prey often evolve to be as cryptic as they can, while predators in turn hone their sensory strategies to detect prey. Examinations of the sensory strategies implemented by predators to detect their prey, as well as the ecological consequences of these interactions, are at the crux of understanding and predicting predator–prey dynamics. We review the sensory strategies used by predators that rely on private information (attending directly to cues and signals generated by their prey) and those that gather social information (attending to the signals and behaviours of others). We focus our enquiry on bats, an ideal group to shed light on these questions given their ecological diversity, varied foraging strategies and wide range of social behaviours. We discuss the costs and benefits of using private and social information for foraging. We investigate diverse strategies of information use and examine the effects different predatory strategies have on predator sensory systems. We provide an overview of the sensory ecology of information use in hunting in bats and, by identifying current gaps in knowledge, highlight fruitful directions for future research. A free Plain Language Summary can be found within the Supporting Information of this article.

Utilisation of oil palm kernel by Hooded Vulture N. monachus in The Gambia

Chapter

Full-text available

Sep 2004

Clive Richard Barlow

The utilisation od oil-palm kernel by N. monachus in The Gambia

Home ranges and movements of Egyptian Vultures Neophron percnopterus in relation to rubbish dumps in Oman and the Horn of Africa

Article

Full-text available

Jan 2019

Capsule: Non-breeding Egyptian Vultures Neophron percnopterus tracked in Oman and the Horn of Africa ranged over large areas and made regular use of anthropogenic sources of food. Tracking data provide evidence that vultures monitor the availability of food within their home ranges. Aims: To study home range and movement patterns of non-breeding Egyptian Vultures. Methods: Five non-breeding Egyptian Vultures were tracked using Global Positioning System technology. Home range sizes were estimated using data only from vultures tracked for more than 11 months, and movements described. Analyses sought to determine whether patterns in movement were related to the location of rubbish dump sites and landfills. Results: Home range sizes of non-breeding Egyptian Vultures (95% kernel density estimator), ranged from 4238 to 7323 km². The average 3-hourly step length ranged from 3106.51 ± 173.16 m (mean ± se; median: 143.72 m; interquartile range, IQR: 2237.41 m) to 6519.46 ± 224.93 m (median: 2131.40 m; IQR: 7098.73 m). Egyptian Vulture activities centred on a few large rubbish dump sites that likely provided perpetually abundant food, but they frequently left those sites and visited other dumps. Conclusions: In line with what is known about Egyptian Vulture ecology, tracked birds ranged over large areas and made use of anthropogenic sources of food. Given the perpetual abundance of food at large rubbish dumps and in the presence of other scavengers feeding at them, there seemed little motivation for Egyptian Vultures to move away from them, unless it was to monitor food resources at other places within their home ranges. This movement behaviour likely reflects the potential benefit to vultures of knowledge about food availability in the wider environment, despite food being abundant at the site at which they are currently located.

Competition for food between vultures in East Africa

Article

Jan 1967

H. Kruuk

Interactions between populations of spotted hyaenas (Crocuta crocuta Erxleben) and their prey species

Article

Jan 1970

H. Kruuk

Body composition as a basis for a comparative study of some East African mammals

Article

Jan 1968

H.P. Ledger

The role of olfaction in food location by the turkey vulture (Cathartes aura)

Article

Jun 1964

Kenneth E. Stager

Competition for Food between Five Species of East African Vultures

Article

Jan 1959

George A. Petrides

Some observations on feeding habits, behaviour and inter-relationships of Northern Rhodesian vultures

Article

Dec 1963

R. I. G. Attwell

Soaring behaviour and performance of some East African birds, observed from a motor-glider

Article

Apr 2008
IBIS

C. J. Pennycuick

Various species of soaring birds were studied by following them in a motor-glider, mainly over the Serengeti National Park, Tanzania. The characteristics of thermal convection in the study area are described in general terms. The two vulture species of the genus Gyps live by scavenging among the herds of migratory ungulates, especially Wildebeest. They are not territorial, and gather in large numbers on kills. When raising young they may be obliged by game movements to forage at long distances from their nests. Their cross-country performance is adequate for a foraging radius of over 100 km in dry-season conditions. Their ability to compete with Spotted Hyaenas is thought to depend partly on this factor and partly on an advantage in arriving early at kills. These two species appear to find food more by watching other vultures than by searching for it directly. The Lappet-faced and White-headed Vultures are thought to be sedentary, and to depend on thorough searching of a fixed foraging territory, rather than on following migratory game. They have lower wing loadings than the Gyps vultures, and were not seen cross-country flying. They never gather in large numbers. The Hooded Vulture is a solitary nester, but it does fly across country, and does gather at kills. Vultures soar individually, and seem to be good at exploiting such phenomena as thermal streets. They do not travel in flocks. Tawny and Martial Eagles react positively to the glider, and are suspected of regarding it as potential prey. White Storks migrate between Europe and Africa, and also travel about within East Africa, by thermal soaring. They soar in flocks, and unlike vultures rely on co-ordinated social behaviour to locate thermals. In choosing their route, they often fail to react to obvious weather signs. They enter cumulus clouds from the bottom when thermalling, but probably do not climb far above cloudbase. Marabou Storks soar individually, but also sometimes travel in flocks. When doing so, they show less lateral spreading than White Storks, which reduces the effectiveness of the flock as a thermal-finding unit; on the other hand, they do seem to react to visible weather signs, like vultures or glider pilots. White Pelicans, which travel by thermal soaring between different lakes in the Rift Valley, show the most highly co-ordinated social soaring behaviour. Unlike White Storks, they fly in formation even when circling. Storks and pelicans showed more signs of alarm when approached by the glider than did the vultures or birds of prey. This could be due to their being preyed upon in flight, for instance by Martial Eagles. The basis of conventional thermal cross-country flying is outlined, and it is explained why the high wing loadings of the Gyps vultures are appropriate to their peripatetic habits. A method of thermal soaring without circling is discussed, and shown to be more readily feasible for small than for large birds. Some differences in soaring techniques between birds and glider pilots are interpreted in the light of this calculation. A case in which Black Kites apparently used this technique to soar in random turbulence is described. The cross-country speed attainable by thermal soaring should be similar to the cruising speed under power in both large and small birds. Rough calculations of the energy costs suggest that a large bird (White Stork) should reduce its fuel consumption by a factor of 23 by soaring rather than flying under power, whereas this factor would be only 2–4 for a small bird (Bonelli's Warbler). Other reasons why thermal soaring is an advantageous means of travel for large but not for small birds are also indicated.

Ecology of Serengeti Vultures

Article

Jan 1973

David C. Houston

Thesis (D. Phil.)--University of Oxford, 1972. Includes bibliographical references.

Some observations on feeding habits, behaviour and inter-relationships of 973) The ecology of Serengeti vulturesin press, a) The role of griffon vultures as scavengersin press, b) The mortality of Gyps coprotheres in southern Africa Competition for food between vultures in East Africa

Feb 1963
171-193

R I G Attwell
D C Houston

ATTWELL, R.I.G. (1963) Some observations on feeding habits, behaviour and inter-relationships of HOUSTON, D.C. (1 973) The ecology of Serengeti vultures. D.Phil. thesis, Oxford University. HOUSTON, D.C. (in press, a) The role of griffon vultures as scavengers. J. Zool. HOUSTON, D.C. (in press, b) The mortality of Gyps coprotheres in southern Africa. Ostrich. KRUUK, H. (1967) Competition for food between vultures in East Africa. Ardea, 55, 171-193.

The role of griffon vultures as scavengers

Houston D.C

The mortality of Gyps coprotheres in southern Africa

Houston D.C

Food searching in Griffon Vultures

Abstract

No full-text available

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