Gyps tenuirostris 

Scope: Global

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Accipitriformes Accipitridae

Scientific Name: Gyps tenuirostris
Species Authority: Gray, 1844
Common Name(s):
English Slender-billed Vulture
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.
Taxonomic Notes: Gyps indicus (Sibley and Monroe, 1990, 1993) has been split into G. indicus and G. tenuirostris following Rasmussen and Parry (2001).

Identification information: 80-95 cm. Thin, rather long-necked vulture. Perched adults have dark bill with pale culmen; black cere; a near-total lack of feathering on the black head and neck. Cold brown overall colouration and scruffy, ill-kempt appearance. Juveniles are very similar but have black head and necks with a hint of white down on the nape and upper neck. Underparts are pale streaked. In flight the white downy thigh patches are distinctive. Similar spp. Jizz is remarkably different from other Gyps vultures due to slender snake-like neck, thin elongated bill, angular crown and scruffy appearance. Eye ring is dark and does not contrast with facial skin. Head and neck skin is bare and thickly creased and wrinkled.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2ce+4ce ver 3.1
Year Published: 2015
Date Assessed: 2015-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Clements, T., Gilbert, M., Htin Hla, T., Khan, M., Rainey, H., Riseborough, R., Mahood, S., Cuthbert, R. & Paudel, K.
Facilitator/Compiler(s): Benstead, P., Bird, J., Butchart, S., Calvert, R., Crosby, M., Symes, A., Taylor, J., Allinson, T, Martin, R & Ashpole, J
This species is classified as Critically Endangered because it has suffered an extremely rapid population decline, particularly across the Indian subcontinent, largely as a result of feeding on carcasses of animals treated with the veterinary drug diclofenac, perhaps in combination with other causes.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Gyps tenuirostris is found in India north of, and including, the Gangetic plain, west to at least Himachal Pradesh and Haryana, south to southern West Bengal (and possibly northern Orissa), east through the plains of Assam, and through southern Nepal, and north and central Bangladesh (BirdLife International 2001). It formerly occurred more widely in South-East Asia, but it is now thought to be extinct in Thailand and Malaysia, and the only recent records are from Cambodia, southern Laos and Myanmar. Considerable confusion over the taxonomy and identification of Gyps vultures has occurred, making it difficult to be sure of claims for this species. However, it appears to be allopatric or parapatric with Indian Vulture G. indicus where their ranges abut (or potentially do so) in northern India.

It was once common, but in South-East Asia populations declined through the latter half of the nineteenth century and the first half of the twentieth century, and are now probably very small and restricted in distribution and limited mainly to Cambodia (where the first nests recorded in the country were recently found and surveys in 2008 recorded a total of 51 individuals at vulture 'restaurants' (H. Rainey in litt. 2008) and Myanmar (counts made at vulture restaurants suggest a population of c.21 individuals [Hla et al. 2010]). Given the lack of intensive agriculture and associated chemical use in South-East Asia and the continued presence of large areas of suitable habitat for the species, the primary reason behind its decline in the region is thought to be the demise of large ungulate populations and improvements in animal husbandry resulting in a lack of available carcasses for vultures (Anon 2003, 2005).

In India and Nepal, the species was common until very recently, but since the mid-1990s it has suffered a catastrophic decline of up to 96.8%, with a combined average decline in India of this species and G. indicus of over 16% annually between 2000 and 2007 (Prakash et al. 2007). The species has also declined in Nepal, with recent surveys in the lowland districts of this country recording no birds (Chaudhary et al. 2011). However in 2014 and 2015, one and two individuals respectively, were recorded along annual road transect surveys in Nepal (K. Paudel in litt. 2015). Data indicates that the rate of population decline of G. tenuirostris and G. indicus combined has now slowed in India (Prakash et al. 2012). Extensive research has identified the non-steroidal anti-inflammatory drug (NSAID) diclofenac to be the cause behind this rapid population collapse (Green et al. 2004, Oaks et al. 2004a, Shultz et al. 2004, Swan et al. 2005). This drug, used to treat domestic livestock, is ingested by vultures feeding on their carcasses, leading to renal failure and causing visceral gout (Oaks et al. 2004a,b; Swan et al. 2005, Gilbert et al. 2006). Probably owing to the effects of diclofenac, breeding success in parts of its Indian range is reportedly low; of 14 nests found in Assam just four had chicks (Choudhury et al. 2005). Diclofenac is apparently entirely absent in Cambodia, adding greater importance to that remaining small population. Likewise, surveys conducted in Myanmar in late 2006 and early 2007 found no firm evidence of diclofenac use (Eames 2007a). Census data from Cambodia suggest that the population there may have been stable since 2004 at least (Eames 2007b). 

Countries occurrence:
Bangladesh; Cambodia; India; Lao People's Democratic Republic; Myanmar; Nepal
Possibly extinct:
Viet Nam
Regionally extinct:
Malaysia; Thailand
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:847000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):2000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Considerable confusion over the taxonomy and identification of Gyps vultures has occurred, making it difficult to be sure of the population size. It is considered likely to number 1,000-2,499 mature individuals, equating to 1,500-3,750 individuals in total.

Trend Justification:  This species declined across South-East Asia during the 20th century probably as a result of the collapse of wild ungulate populations and, to some degree, persecution. Since the mid-1990s, declines have been noted in three species of Gyps vulture across the Indian Subcontinent, including this species. These declines are driven by high adult mortality as a result of residues of the anti-inflammatory drug diclofenac used to treat domestic livestock. An extremely rapid decline is estimated to have occurred over the last three generations.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:1000-2499Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:It inhabits dry open country and forested areas usually away from human habitation. In South-East Asia it was found in open and partly wooded country, generally in the lowlands. This species feeds almost entirely on carrion, scavenging at rubbish dumps and slaughterhouses, and at carcasses dumped in the fields and along rivers. It has only been recorded nesting in trees, usually large ones, usually at a height of 7-25 m, sometimes near villages but usually more remote. It is a solitary nester. While feeding, considerable mixed species aggregations can form, and regular communal roost sites are used. It is social and usually found in conspecific flocks, interacting with other vultures at carcasses. Movements are poorly known, and the degree of connectivity of apparently separate populations is not known. Vultures also play a key role in the wider landscape as providers of ecosystem services. They were previously heavily relied upon to help dispose of animal and human remains in India.

Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):16
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): By mid-2000, Gyps vultures were being found dead and dying in Nepal, Pakistan, and throughout India, and major declines and local extirpations were being reported. The anti-inflammatory drug diclofenac, used to treat domestic livestock, has been identified as the cause of mortality, with renal failure resulting in visceral gout in the vast majority of examined vultures (Oaks et al. 2004a, Shultz et al. 2004, Swan et al. 2005, Gilbert et al. 2006). Modelling has shown that to cause the observed rate of decline in Gyps vultures, just one in 760 livestock carcasses need contain diclofenac residues (Green et al. 2004). Despite awareness programmes to educate locals about the association between diclofenac and vulture mortality, a survey in Nepal indicated that the vast majority of people still do not link diclofenac use to a decline in vulture populations (Anon 2009), potentially leading to a slower uptake of a vulture safe alternative drug (meloxicam). A second veterinary drug in use in India and Nepal, ketoprofen, has also recently been identified to be lethally toxic to the related Gyps species, and population modelling indicates residues of this drug are found in ungulate carcasses in India at sufficient concentrations to cause mortalities. It may be present in sufficient concentrations to also cause population declines (Naidoo et al. 2009). Other likely potential contributory factors are changes in human consumption and processing of dead livestock, avian malaria (Poharkar et al. 2009), and poison and pesticide use, but these are probably of minor significance. In South-East Asia, the near-total disappearance of the species pre-dated the present crisis, and probably results from the collapse of large wild mammal populations and improved management of deceased livestock leading to scarcity of available food (Clements et al. 2013), but persecution and poisoning is also thought to be a problem. In Cambodia vultures are still threatened by extremely low population densities of wild ungulates, a decline in the number of free-ranging domestic ungulates, felling of nesting trees for timber and accidental poisoning at carcasses laced with pesticides to kill stray dogs (S. Mahood in litt. 2012).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
CITES Appendix II. CMS Appendix II. It has been reported from many protected areas across its range. The governments of India, Nepal and Pakistan passed legislation in 2006 banning the manufacture and importation of diclofenac as a veterinary drug, with India passing further legislation in 2008 banning the manufacture, sale, distribution or use of veterinary diclofenac. A letter from the Drug Controller General of India in 2008 warned more than 70 drugs firms not to sell the veterinary form of diclofenac, and to mark human diclofenac containers 'not for veterinary use' (BirdLife International 2008). In October 2010, the government of Bangladesh banned the production of diclofenac for use in cattle, and the distribution and sale of the drug were due to be outlawed during the first half of 2011 (M.M.H. Khan in litt. 2010). While these bans have been introduced and have led to a reduction of diclofenac within ungulate carcasses (the principal food source for vultures in South Asia) levels of diclofenac contamination still remain high and human forms of the drug are still sold for veterinary use (Cuthbert et al. 2011a,b). Efforts to replace diclofenac with a suitable alternative are on-going and are showing signs of success with evidence for a decrease in diclofenac and an increase in the safe alternative (Cuthbert et al. 2011c ). An alternative drug, meloxicam, which is out of patent and manufactured in Asia has been tested on Gyps vultures with no ill-effects (Swan et al. 2006, Swarup et al. 2007). SAVE (Saving Asia's Vultures from Extinction) has developed the concept of Vulture Safe Zones; areas (with a minimum of 100 km radius, equating to 30,000 km2) around important vulture breeding colonies, where education and advocacy efforts are focussed on eliminating the use of diclofenac and other vulture-toxic drugs (Galligan 2013, Mukherjee et al. 2014). There are currently 12 provisional Vulture Safe Zones being established in countries including India, Nepal and Bangladesh (Mukherjee et al. 2014). These areas will provide a safe environment into which birds bred in captivity can be released (Bowden et al. 2012).

Vulture restaurants are used as ecotourism attractions in parts of the species's range to raise awareness and fund supplementary feeding programmes and research - in Cambodia these are run by The Cambodia Vulture Conservation Project and a partnership between national and international conservation NGOs (e.g. Masphal and Vorsak 2007, H. Rainey in litt. 2008). Birds have been satellite tagged in various parts of their range to improve understanding of their movements, foraging range, site fidelity etc., in order to develop suitable conservation strategies for the species (Ellis 2004). Socioeconomic surveys in Nepal have shown that local people are strongly in favour of vulture conservation because of the associated ecological services that they provide (Gautam and Baral 2003).

The Report of the International South Asian Vulture Recovery Plan Workshop in 2004 gave a comprehensive list of recommendations including establishing a minimum of three captive breeding centres each capable of holding 25 pairs (Bombay Natural History Society 2004). Captive breeding efforts began in 2006 when 18 Slender-billed Vultures were captured for the captive-breeding facility in Pinjore, India. The centre is part of a captive breeding programme established by the RSPB and Bombay Natural History Society. In April 2008, there were 28 birds at the three Indian breeding centres (Pain et al. 2008), increasing to 35 birds in 2009 (Bowden 2009). Two individuals bred in captivity for the first time in 2009 (Anon 2009). By November 2011, the total number in breeding centres affiliated to SAVE was 47 birds (SAVE 2012), of which five juveniles had successfully fledged by November 2011 (Bowden et al. 2012). A website has been set up to allow researchers to contribute data on known colonies to identify founder individuals for captive breeding efforts that represent the full geographical spread of the species (M. Gilbert in litt. 2004). Captive breeding centres often receive vultures that have been found poisoned and then rehabilitated by rescue centres such as the Centre for Wildlife Rehabilitation and Conservation, Assam, which is run by the International Fund for Animal Welfare (IFAW) and the Wildlife Trust of India (Wildlife Trust of India 2009). Surveys utilising vulture restaurants were carried out in Myanmar in late 2006 and early 2007, accompanied by searches for nesting colonies, research into vulture deaths and investigation of possible diclofenac use in livestock (Eames 2007a).

In 2012 the governments of India, Pakistan, Nepal and Bangladesh adopted a number of priority actions for the conservation of vultures, proposed by SAVE. These include banning large multi-dose vials of human diclofenac, testing other NSAIDs for toxicity to vultures and expanding the Vulture Safe Zones initiative (Galligan 2013).

Conservation Actions Proposed
Identify the location and number of remaining individuals and identify actions required to prevent extinction. Measure the frequency of diclofenac treated carcasses available to vultures. Support the ban on the veterinary use of diclofenac, and support species management or restoration, as needed. Initiate public awareness and public support programmes. Monitor remaining populations, in particular replicate conservation and research activities in Myanmar that have been implemented in Cambodia. Provide supplementary food sources where necessary for food-limited populations in South-East Asia. Support captive breeding efforts at a number of separate centres. Promote the immediate adoption of meloxicam as an alternative to diclofenac. Test other NSAIDs to identify additional safe alternative drugs to diclofenac and also other toxic ones. Two drugs, aceclofenac and ketoprofen, are known to be toxic to vultures, approximately another 10 drugs need to be tested (Galligan 2013).

Citation: BirdLife International. 2015. Gyps tenuirostris. The IUCN Red List of Threatened Species 2015: e.T22729460A79511733. . Downloaded on 24 October 2016.
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