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Current Biology
R560 Current Biology 26, R543–R576, July 11, 2016 © 2016 Published by Elsevier Ltd.
Evan R. Buechley*
and Cagan H. Sekercioglu
What are vultures? Vultures are large,
obligate scavenging birds that eat dead
vertebrates. There are 23 species of
vulture, inhabiting diverse biomes from
the Amazonian rainforest and East
African savannahs, to the Sahara Desert
and high Himalayas. There are two main
groups of vultures: Old World vultures of
the Accipitridae family, found in Europe,
Africa, and Asia, and New World
vultures of the Cathartidae family, found
in North and South America. It was long
believed that New World vultures were
more closely related to storks than to
Old World vultures. However, recent
molecular evidence indicates that
they are likely to be sister taxa. Either
way, the scavenging habits of these
groups are thought to have evolved
independently, leading to adaptations
like large bodies, broad wings, powerful
beaks and featherless heads.
How do vultures fi nd and feast on
rotting fl esh? Carrion is a temporally and
spatially unpredictable resource, which
vultures are uniquely adapted to exploit.
They soar to search for food over vast
areas with minimal energy expenditure.
Accordingly, vultures have some of the
largest ranges of any animals on Earth.
While only three of 23 vulture species are
true long-distance migrants (turkey, black
and Egyptian vultures), others, such as
those in the genus Gyps, e.g. Eurasian
griffon vultures, have individual foraging
ranges of hundreds of thousands of
square-kilometers (approximately the
size of Spain). Vultures are also among
the largest birds in the world, which
enables them to store suffi cient energy
while covering vast distances in search of
their next meal. For example, the Andean
condor weighs over 11 kg and has an
impressive wingspan of up to 3.2 m.
Even more impressively, the extinct
vulture Argentavis magnifi cens had a
wingspan of approximately 7 m and a
mass of around 80 kg.
Effi cient energy management is a key
adaptation of vultures. For instance,
vultures’ featherless heads were long
thought to be an adaptation to keep
Quick guide
carrion under dense rainforest canopies
or buried beneath leaf litter and can lead
their relatives, the black and king vultures,
to hidden meals they otherwise would
not fi nd. Mammalian scavengers, such as
jackals and hyenas, also follow vultures,
making them a keystone species of the
scavenger community. Once they drop
to a carcass, a group of feeding vultures,
known as a ‘wake’, can facilitate ripping
through tough hide, fend off competitors,
and warn of potential threats.
Interestingly, vultures have highly
specialized feeding niches. In the
African savannah, Ruppell’s and white-
backed vultures gorge on internal
organs; lappet-faced vultures use their
powerful beaks to dine on ligaments
and hide; white-headed and hooded
vultures circle the feeding frenzy picking
up scraps; and then the massive
bearded vulture, the world’s only
vertebrate osteophage (bone-eating
specialist), swallows large chunks of the
skeleton whole or carries and drops the
bones at an ossuary to break them into
clean while foraging on rotting fl esh.
But, new research suggests that when
vultures change posture, they can
expose or cover large swaths of skin
with their neck feathers allowing them
to manage thermal radiation. Another
unusual heat management adaptation is
urohydration — or the New World vultures’
habit of defecating and urinating on their
legs, which provides evaporative cooling.
To effi ciently locate carrion, vultures
use cues from their cohorts. From their
vantage point, high in the sky, most
vulture species rely on vision to fi nd
food. This poses a challenge because
carcasses are not moving and may be
obstructed from view. However, when
one bird fi nds and circles a carcass, it
alerts its comrades of a potential meal.
Soon, more curious vultures investigate,
forming a ‘kettle’, a group of vultures
circling a carcass, which indicates an
impending feast to scavengers far and
wide. Furthermore, New World vultures
in the genus Cathartes also have a keen
sense of smell: turkey vultures can locate
Figure 1. Vultures.
Critically Endangered white-backed vultures (Gyps africanus) in Ethiopia.
Current Biology
Current Biology 26, R543–R576, July 11, 2016 © 2016 Elsevier Ltd. R561
smaller pieces. After the vultures’ wake,
often little remains of the carcass.
How are vultures doing? Nine of 23
vulture species (39%) are classed as
‘Critically Endangered’, i.e. on the brink
of extinction (Figure 1). An additional
three species are Endangered, four are
Near Threatened, and seven are Least
Concern. Over the past three decades,
vultures have declined catastrophically,
especially in Asia and Africa, and are
now the most threatened group of bird
in the world. Persecution, decreasing
food availability, habitat destruction,
and collision with energy infrastructure
all threaten vultures. However,
poisoning is the most imminent and
dire threat, as it is incredibly effective at
killing vultures. For example, in 2013, a
single contaminated elephant carcass
in Namibia killed 600 vultures.
Throughout Africa, vulture populations
are crashing. Over three generations,
the bearded vulture declined by 70%,
while seven other species declined
by 80% or more. Accordingly, four
African vulture species were classed
as Critically Endangered in 2015. The
deliberate poisoning of mammalian
carnivores, such as jackals, hyenas, and
lions, to avenge livestock loss, has led
to widespread unintentional poisoning
of vultures. And now, with the boom of
illegal rhino and elephant hunting across
the continent, poachers are intentionally
poisoning vultures because their
carcass circling cues can quickly lead
authorities to the scene of the crime.
The current acute situation in Africa is a
worrying déjà vu of the extreme declines
in South Asia, where populations of
three vulture species declined by >95%
between 1992 and 2007 due to poisoning
from the anti-infl ammatory veterinary
drug Diclofenac. This drug, widely used
to treat pain and swelling in sacred cattle,
causes kidney failure in vultures after
ingestion. Because of the drug’s lethality
and vultures’ social foraging, only <1% of
livestock carcasses would have needed
to contain the drug to account for these
declines. Encouragingly, India, Pakistan
and Iran have banned the use of the drug
for veterinary purposes, but it remains
on the market in many other countries,
including throughout Europe.
Why should we care about vulture
declines? By quickly locating
and consuming carrion, vultures
outcompete and control problematic
facultative scavengers (like feral dogs
and rats), insects, and microorganisms.
When vulture populations decline,
carrion becomes increasingly available
to other organisms, in a form of terrestrial
eutrophication. Currently, many facultative
scavenger populations are increasing
worldwide, causing signifi cant top-down
ecosystem effects via predation, invasion
and competition. Furthermore, carcasses
provide a reservoir and vector for many
diseases, including rabies, chronic
wasting, anthrax, bubonic plague, mad
cow, foot and mouth, etc. Vultures have
extremely acidic stomachs (pH = 1.0)
where most viruses and bacteria cannot
survive. When vultures eat carcasses,
they actively remove these pathogens
from the environment, as well as preempt
the colonization and reproduction of
pestilent insects.
Vultures offer valuable ecosystem
services and are a fascinating group
of birds highly adapted for their unique
lifestyle. They have often been portrayed
as malevolent creatures preying on
the sick and weary. But the reality
could not be further from the truth:
vultures are the “soap of the savannah”,
quickly and effi ciently removing waste,
controlling pests, and preventing
disease outbreaks — all free of charge.
And, as true apex carnivores — eating
all animals in the food chain, including
lions, tigers, and bears — they are
excellent indicators of ecosystem health.
Where can I fi nd out more?
Buechley, E.R., and Sekercioglu, Ç.H. (2016) The
avian scavenger crisis: Looming extinctions,
trophic cascades, and loss of critical ecosystem
functions. Biol. Conservat. 198, 220–228.
Markandya, A., Taylor, T., Longo, A., Murty, M.N.,
Murty, S., and Dhavala, K. (2008). Counting
the cost of vulture decline—An appraisal of the
human health and other benefi ts of vultures in
India. Ecol. Econ. 67, 194–204.
Mundy, P.P., Bunchart, D., Ledger, J., and Piper, S.
(1993). The Vultures of Africa (Academic Press).
Ogada, D.L., Keesing, F., and Virani, M. (2012).
Dropping dead: causes and consequences of
vulture population declines worldwide. Ann. N.Y.
Acad. Sci. 1249, 57–71.
Royet, E. (2016). Vultures are Revolting. Here’s
Why We need to Save Them. Natl. Geogr. Mag.
Available at: http://ngm.nationalgeographic.
Sodhi, N.S., Sekercioglu, C.H., Robinson, S., and
Barlow, J. (2011). Conservation of Tropical Birds.
Wiley-Blackwell. Oxford.
Wilson, E.E., and Wolkovich, E.M. (2011). Scavenging:
how carnivores and carrion structure communities.
Trends Ecol. Evol. 26, 129–135.
University of Utah, Department of Biology, 257 S.
1400 E. Rm. 201, Salt Lake City, UT 84112, USA.
Microbiology of
Jessica L. Metcalf1,2,*,
David O. Carter3, and Rob Knight2,4,5
When a mammal dies, what
happens? Decomposition happens.
When a mammal dies its immune
system shuts down, internal
temperatures change, and internal
bacteria begin to grow in ways
impossible while under the constraints
of a living host. The internal
environment then experiences another
major event: rupture a break in the
skin that allows air, microbes, and
insects to enter, and bodily fl uids to
exit. A carcass releases large amounts
of nitrogen into the environment,
mostly in the form of ammonia, as well
as carbon, phosphorous, and other
nutrients important for life. A dead
body becomes a hotspot of nutrients,
water, and ecological activity.
How do we study mammalian
decomposition? What is an
anthropological research facility?
You may have heard the term ‘body
farm’ in the news or on popular
forensic science shows like Bones
or CSI. In the scientifi c community,
these research centers are more
appropriately called ‘anthropological
research facilities’, and are important
for studying the anthropological,
ecological, and forensic science
implications of mammalian
decomposition. Because of the
interest in human decomposition
for anthropology and its practical
importance in forensic science, these
facilities use human donors for fi eld
experiments to test the effects of
different variables on taphonomy the
processes of decomposition. Some
facilities also use pigs, which are good
biological proxies for humans and
allow for more replicates and better
control over factors such as age,
weight, and sex.
What organisms are involved in
decomposition? Decomposition is
one of the most important ecosystem
processes if it were not effi ciently
Quick guide
... V ultures are an avian species and are deemed as the most successful scavengers and at the highest level of decomposers (Samson et al., 2018). There are 23 species of vultures found across the world, including areas like the Amazon forests, African savannas, Saharan deserts, and high roof of Himalayas (Buechley and Sekercioglu, 2016). They act as an obligate scavenger and provide important economic, ecologic, and cultural services to mankind (Sekercioglu, 2006). ...
... tenuirostris, G. bengalensis, G. indicus) is an important issue. This high drop off in the vulture population was found due to exposure of these birds to diclofenac Johnson et al., 2008;Rattner et al., 2008;Naidoo and Swan, 2009;Buechley and Sekercioglu, 2016;Galligan et al., 2016). This drug was found extremely toxic to vulture populations and mortality resulted within few days after exposure (Rattner et al., 2008;Johnson et al., 2008;Naidoo and Swan, 2009). ...
Full-text available
Worldwide there are 23 species of vultures. The vultures are known as one of nature’s most successful scavengers. However, since the 1990’s vulture numbers in South East Asia have been in decline, especially the oriental white-rumped vulture (Gyps bengalensis), the long-billed vulture (Gyps indicus), and the slender-billed vulture (Gyps tenuirostris). The use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac has been linked to this rapid decline in vulture populations. Diclofenac has been in use since 1974 to treat several problems in cattle such as pain during calving, lameness, mastitis, and swelling. The drug was also used to treat diverse problems such as dysmenorrhea, ocular inflammation, rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, and actinic keratosis etc. Although, it is good for livestock, its impact on the vulture population has been very deleterious. The present review discusses the chemical structure, uses, and the mechanism of the action of diclofenac and its negative impacts on vulture populations along with less harmful alternatives such as meloxicam, and controlling measures to stop decline of vulture species that can be adopted to regain normal population numbers of these vulture species
... However, according to the International Union for Conservation of Nature (IUCN) Red List, Andean condor populations are globally near-threatened and declining (BirdLife International, 2019), because, besides having very low reproductive rates, they have been threatened by anthropogenic effects such as: poisoning by pesticides, lead ammunition and toxic baits, collisions with power lines, poaching, snare traps and decrease in food (Campbell, 2016;Pavez & Estades, 2016;Wiemeyer et al., 2017). Although vulture species are essential for ecosystem health and functioning, providing a highly effective sanitation service (Monadjem, Kane, Botha, Kelly, & Murn, 2018;Muñoz-Lozano et al., 2019;Ogada, Keesing, & Virani, 2012), they have experienced the most rapid decline in conservation status of any group of birds over the past decade and comprise the most threatened avian group in the world (Buechley & Şekercioğlu, 2016a(Buechley & Şekercioğlu, , 2016bOgada et al., 2012). ...
Critical priority pathogens have globally disseminated beyond clinical settings threatening wildlife. Andean Condors are essentials for ecosystem health and functioning, but their populations are globally near threatened and declining due to anthropogenic activities. During a microbiological and genomic surveillance study of critical priority antibiotic-resistant pathogens we have identified pandemic lineages of multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing Escherichia coli colonizing Andean Condors admitted at two wildlife rehabilitation centres in South America. Genomic analysis revealed presence of genes encoding resistance to hospital and health-care agents among international E. coli clones belonging to sequence types (STs) ST162, ST602, ST1196 and ST1485. In this regard, resistome included genes conferring resistance to clinically important cephalosporins [i.e., CTX-M-14, CTX-M-55 and CTX-M-65 extended-spectrum β-lactamase (ESBL) genes], heavy metals (arsenic, mercury, lead, cadmium, copper, silver), pesticides (glyphosate), and domestic/hospital disinfectants (QACs), suggesting a link with anthropogenic environmental pollution. On other hand, presence of virulence factors, including astA gene associated with outbreak of childhood diarrhoea and extraintestinal disease in animals, were identified, whereas virulent behaviour was confirmed using the Galleria mellonella infection model. E. coli ST162, ST602, ST1196 and ST1485 have been previously identified in humans and food-producing animals worldwide, indicating that a wide resistome could contribute with rapid adaptation and dissemination of these clones at the human-animal-environment interface. Therefore, these results highlight that Andean Condors have been colonized by critical priority pathogens, becoming potential environmental reservoirs and/or vectors for dissemination of virulent and antimicrobial-resistant bacteria and/or their genes, in associated ecosystems and wildlife.
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Scavenging is an important ecological process. By quickly locating and consuming carrion, vertebrate scavengers cycle nutrients, stabilize food webs, and may help mitigate disease transmission to humans. Across Africa, many scavengers feed at abattoirs (i.e. slaughterhouses), thereby aiding in waste removal. Little information exists on the scavenger community composition and dynamics at abattoirs, and, to our knowledge, the carrion removal that scavengers provide at these sites has never been quantified. We studied vertebrate scavenger ecology at 6 abattoirs in Ethiopia with time‐lapse photography and in‐person surveys from 2014–2019. Specifically, we investigated daily, seasonal, and inter‐annual patterns in use of abattoirs by vertebrate scavengers and estimated carrion consumption rates. We demonstrated the importance of abattoirs for supporting a large number and diversity of scavenger species, including 3 critically endangered, 2 endangered, 1 vulnerable, and 2 regionally endemic bird species. At the start of the study, vultures contributed 57% of carrion removal provided by vertebrate scavengers. Detections of critically endangered Rüppell's (Gyps rueppelli) and white‐backed (G. africanus) vultures declined by 73% and critically endangered hooded vultures (Necrosyrtes monachus) declined by 15% over the study period. Simultaneously, the detections of dogs more than doubled. Using estimates of species‐specific carrion consumption rates from the literature, coupled with changes in scavenger detections in our study, we estimated a 12% (54 kg/day) reduction in carrion consumption, or nearly 20,000 kg carrion less consumed per year by the end of the study at these 6 abattoirs. Our results indicate that ongoing vulture declines across Africa could significantly reduce carrion removal. We recommend that improving fencing around abattoir facilities could help restrict access by feral dogs, increase foraging by vultures, and, therefore, increase overall carrion removal rates. We studied scavenger ecology over 5 years in Ethiopia and vultures consumed 57% of the carrion at the start of the study, but detections declined substantially while feral dog detections doubled. Overall ecological function (carrion consumption) was reduced and we recommend adaptive fencing around abattoir waste disposal sites.
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Due to an abundance and diversity of vultures, Nepal is one of the most important countries for vulture conservation. Within Nepal, the Pokhara Valley is especially significant. We examine the distribution of vultures within the Pokhara Valley by conducting counts at 11 potential feeding or roosting sites using point count method. We further surveyed people of the valley regarding their perception of vulture ecology and conservation, knowledge of diclofenac use within the valley, and burial of livestock carcasses. We detected eight species of vultures, four of which are currently threatened with extinction. White-rumped vulture Gyps bengalensis, Egyptian vulture Nephron percnopterus, and Himalayan vulture G. himalayensis were the most abundant. Almost all respondents (98%) had sighted the vultures in the wild. Formally educated respondents reported seeing vultures’ slightly more than non-formally educated respondents. Fifty eight percent respondents suspected habitat loss was the major threat for the vulture population decline in Pokhara Valley, and 97% respondents were not aware of any diclofenac use. The knowledge of vultures in people with different age groups suggests a more awareness programs are needed for local people, especially those who carry out animal husbandry and provide livestock to the vulture restaurant.
Biodiversity is vital to the welfare and survival of humans, but public support for conservation of most animal species is appallingly limited. Vertebrates make up less than 5% of the world’s documented animal species, but are viewed far more sympathetically than invertebrates. This is because humans are empathetic with the appearance and behaviour of many of them, particularly the charismatic superstars like pandas and tigers that currently are the mainstays of biodiversity fundraising. Conversely, just as such attractive icons are effective ambassadors of biodiversity conservation, so certain detested and sometimes dangerous vertebrate pests have greatly compromised the public image of biodiversity. Some of these species, admittedly, are responsible for significant damage to health and economic welfare. Nevertheless, this paper shows that all play important ecological roles, they have compensating economic values, their harm has often been exaggerated, and their very negative public images are undeserved. This first installment deals with the most reviled ‘lower’ vertebrate species: sharks (representing fish); frogs and toads (representing amphibians); snakes (representing reptiles); and vultures (representing birds). The next contribution will deal with mammals.
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Old World vultures are experiencing dramatic population declines and now are among the species most threatened with extinction. Understanding the environmental variables that can influence the reproductive indexes of vulture populations can facilitate both habitat and species management. The aim of this study was to identify which environmental variables primarily affect the breeding successes of the Griffon Vulture Gyps fulvus in the northern Sardinia Island by applying a Bayesian hierarchical model (BHM). A unique dataset of reproductive records (197 nests monitored over 39 years for a total of 992 breeding records) was used. Eight environmental and topographic variables describing the habitat at the nesting sites were considered as potential predictors of breeding success. These included mean annual temperature, mean annual precipitation, isothermality, elevation, the normalized difference vegetation index (NDVI), wind speed, and the aspect and slope of the land surface. In addition, we also considered the effect of human disturbance and the type of nest. According to our best model, the probability of successfully raising a chick in Griffon Vultures was higher in nests exposed to a high wind speed, not covered by natural shelters, where the vegetation was mostly represented by shrub and pastures, with low human disturbance and in years with low rainfall. This model will be useful to the management of the breeding habitat and to identify the area most suitable for Griffon Vulture reproduction. This information is crucial for programming conservation measures aimed at enlarging the area of occupancy of the species.
Full-text available
Vulture populations are in severe decline across Africa and prioritization of geographic areas for their conservation is urgently needed. To do so, we compiled three independent datasets on vulture occurrence from road-surveys, GPS-tracking, and citizen science (eBird), and used maximum entropy to build ensemble species distribution models (SDMs). We then identified spatial vulture conservation priorities in Ethiopia, a stronghold for vultures in Africa, while accounting for uncertainty in our predictions. We were able to build robust distribution models for five vulture species across the entirety of Ethiopia, including three Critically Endangered, one Endangered, and one Near Threatened species. We show that priorities occur in the highlands of Ethiopia, which provide particularly important habitat for Bearded Gypaetus barbatus , Hooded Necrosyrtes monachus , Rüppell’s Gyps rüppelli and White-backed Gyps africanus Vultures, as well as the lowlands of north-eastern Ethiopia, which are particularly valuable for the Egyptian Vulture Neophron percnopterus. One-third of the core distribution of the Egyptian Vulture was protected, followed by the White-backed Vulture at one-sixth, and all other species at one-tenth. Overall, only about one-fifth of vulture priority areas were protected. Given that there is limited protection of priority areas and that vultures range widely, we argue that measures of broad spatial and legislative scope will be necessary to address drivers of vulture declines, including poisoning, energy infrastructure, and climate change, while considering the local social context and aiding sustainable development.
Full-text available
Raptors are high in trophic level and play an essential role in the functioning of an ecosystem, yet not much information about their distribution and abundance is available from the Indian Himalayan region. The present study was conducted in the Indian part of the Kailash sacred landscape, Western Himalayas, between February 2015–December 2017, documenting the distribution and abundance status of raptors in the landscape. Altogether, 320 km of trails were walked, and 1162 km of the vehicular survey were conducted through different habitats. A total of 506 individuals of 25 species belonging to three families were recorded. Nine Globally Threatened/Near Threatened species and eight migrant species were observed from the landscape. Himalayan vulture Gyps himalayensis was the most abundant and widely distributed raptor, followed by Black-eared kite Milvus migrans lineatus and Steppe eagle Aquila nipalensis. The population of raptors is declining worldwide, and in the Kailash landscape, this lesser-known group should be monitored regularly and protected by ensuring the availability of suitable and undisturbed habitat, control on forest fire, and uncontaminated food.
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Obligate scavenging on dead and decaying animal matter is a rare dietary specialization that in extant vertebrates is restricted to vultures. These birds perform essential ecological services, yet many vulture species have undergone recent steep population declines and are now endangered. To test for molecular adaptations underlying obligate scavenging in vultures, and to assess whether genomic features might have contributed to their population declines, we generated high-quality genomes of the Himalayan and bearded vultures, representing both independent origins of scavenging within the Accipitridae, alongside a sister taxon, the upland buzzard. By comparing our data to published sequences from other birds, we show that the evolution of obligate scavenging in vultures has been accompanied by widespread positive selection acting on genes underlying gastric acid production, and immunity. Moreover, we find evidence of parallel molecular evolution, with amino acid replacements shared among divergent lineages of these scavengers. Our genome-wide screens also reveal that both the Himalayan and bearded vultures exhibit low levels of genetic diversity, equating to around a half of the mean genetic diversity of other bird genomes examined. However, demographic reconstructions indicate that population declines began at around the Last Glacial Maximum, predating the well-documented dramatic declines of the past three decades. Taken together, our genomic analyses imply that vultures harbour unique adaptations for processing carrion, but that modern populations are genetically depauperate and thus especially vulnerable to further genetic erosion through anthropogenic activities.
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Conservation of Tropical Birds has been written by four conservation biologists whose expertise spans all the tropical regions of the world. It is the first book to cover all the major issues in tropical bird conservation. Current problems faced by tropical bird conservationists are summarised and potential solutions outlined based on the results of case studies. Birds are key indicators of ecosystem health, and such a well-studied group of organisms, that they provide an excellent lens through which to examine global conservation problems caused by phenomena such as climate change, declines in ecosystem services, habitat loss, fires, overexploitation, and invasive species. Therefore, the book also provides an engaging synopsis of the general issues in conservation and the problems faced by other wildlife. This book serves as an important resource and companion to all people interested in observing and conserving birds in the tropics and elsewhere. © 2011 Navjot S. Sodhi, Cagan H. Sekercioglu, Jos Barlow, Scott K. Robinson.
Full-text available
Vultures are nature's most successful scavengers, and they provide an array of ecological, economic, and cultural services. As the only known obligate scavengers, vultures are uniquely adapted to a scavenging lifestyle. Vultures' unique adaptations include soaring flight, keen eyesight, and extremely low pH levels in their stomachs. Presently, 14 of 23 (61%) vulture species worldwide are threatened with extinction, and the most rapid declines have occurred in the vulture-rich regions of Asia and Africa. The reasons for the population declines are varied, but poisoning or human persecution, or both, feature in the list of nearly every declining species. Deliberate poisoning of carnivores is likely the most widespread cause of vulture poisoning. In Asia, Gyps vultures have declined by >95% due to poisoning by the veterinary drug diclofenac, which was banned by regional governments in 2006. Human persecution of vultures has occurred for centuries, and shooting and deliberate poisoning are the most widely practiced activities. Ecological consequences of vulture declines include changes in community composition of scavengers at carcasses and an increased potential for disease transmission between mammalian scavengers at carcasses. There have been cultural and economic costs of vulture declines as well, particularly in Asia. In the wake of catastrophic vulture declines in Asia, regional governments, the international scientific and donor communities, and the media have given the crisis substantial attention. Even though the Asian vulture crisis focused attention on the plight of vultures worldwide, the situation for African vultures has received relatively little attention especially given the similar levels of population decline. While the Asian crisis has been largely linked to poisoning by diclofenac, vulture population declines in Africa have numerous causes, which have made conserving existing populations more difficult. And in Africa there has been little government support to conserve vultures despite mounting evidence of the major threats. In other regions with successful vulture conservation programs, a common theme is a huge investment of financial resources and highly skilled personnel, as well as political will and community support.
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Widespread use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac to treat livestock has resulted in dramatic declines in the populations of vultures across India. This has become an issue of considerable concern as vultures are a keystone species and their decline has a range of socio-economic, as well as cultural and biodiversity impacts. In this paper, we review these impacts and estimate in detail the economic cost of one of them: the human health impacts of the vulture decline. Livestock carcasses provide the main food supply for vultures, and are also eaten by dogs. Dogs are the main source of rabies in humans in India, and their populations have increased substantially in parallel with the vulture decline. The potential human health impact of rabies associated with the vulture decline is found to be significant. This, and a wide range of other impacts suggest that significant resources should be put into (1) testing of pharmaceutical products to ensure that similar situations are not repeated, (2) helping vulture populations to recover through the use of alternative drugs to diclofenac that are of low toxicity to vultures, and (3) through conservation breeding programmes.
Vultures, which are the only obligate vertebrate scavengers, have experienced the most rapid decline in conservation status of any group of birds over the past decade and comprise the most threatened avian functional guild in the world. Of the 22 vulture species, nine are critically endangered, three are endangered, four are near threatened, and six are least concern. Meanwhile, the vast majority of avian facultative scavenger species, such as corvids and gulls, have stable or increasing populations. We analyze the causes of this stark contrast in status and evaluate what ecological factors contribute to extinction risk for all 106 avian scavenger species. A random forest model shows that diet breadth, proportion scavenged diet, geographic realm, body mass, clutch size and taxonomy are leading predictors of extinction risk. Meanwhile, dietary toxins – most notably poisons and the veterinary drug diclofenac – are by far the most important anthropogenic threat to avian scavengers, comprising the leading cause of decline for 59% of threatened avian scavenger species and 88% of threatened vulture species. Currently, 73% of vulture species are extinction-prone (near threatened, vulnerable, endangered, critically endangered and extinct) and 77% have declining populations, while only 13% of avian facultative scavenger species are extinction-prone and 70% have stable or increasing populations. As vultures decline, populations of many facultative scavengers are growing, causing trophic cascades from increased predation, competition, and invasion. Furthermore, vultures' highly specialized digestive systems efficiently eradicate diseases when consuming carrion, whereas facultative scavengers are more susceptible to contract and transmit diseases among themselves and to humans. We urge immediate action, particularly by regulating lethal dietary toxins, to prevent the extinction of vultures and loss of respective ecosystem services.
Recent advances in the ecology of food webs underscore the importance of detritus and indirect predator-prey effects. However, most research considers detritus as an invariable pool and predation as the only interaction between carnivores and prey. Carrion consumption, scavenging, is a type of detrital feeding that should have widespread consequences for the structure and stability of food webs. Providing access to high-quality resources, facultative scavenging is a ubiquitous and phylogenetically widespread strategy. In this review, we argue that scavenging is underestimated by 16-fold in food-web research, producing inflated predation rates and underestimated indirect effects. Furthermore, more energy is generally transferred per link via scavenging than predation. Thus, future food-web research should consider scavenging, especially in light of how major global changes can affect scavengers.
Vultures are Revolting. Here's Why We need to Save Them
  • E Royet
Royet, E. (2016). Vultures are Revolting. Here's Why We need to Save Them. Natl. Geogr. Mag. Available at: http://ngm.nationalgeographic. com/2016/01/vultures-text.