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Recent changes in populations of resident Gyps vultures in India
Abstract and Figures
Nine species of vultures are recorded from Indian subcontinent. The populations of three resident Gyps species, namely Oriental White-rumped Vulture Gyps bengalensis, Long-billed Vulture Gyps indicus and Slender-billed Vulture Gyps tenuirostris crashed during the mid nineties of the last century. Vulture declines were first documented at Keoladeo National Park, Bharatpur, Rajasthan. Subsequently, the crash in populations was documented across the country. During the present study, surveys on identified tracks were done in 2007 to repeat surveys done previously in 1992, 2000, 2002 and 2003. This was done to determine the population trend in the three species of vultures and also to get a rough estimate of the surviving population of vultures in 2007. The latest repeat surveys were carried out from March to June 2007 by driving in a motor vehicle and recording vultures within 500 m on the either side of each transect. The results indicate that the population of the three species of vultures continues to decline at an alarming rate. Numbers of Oriental White-rumped Vulture declined by 99.9% between 1992 and 2007 on the transects surveyed each year during that period. The equivalent decline in the combined total of Gyps indicus and G. tenuirostris was 96.8%. The population of Oriental White-rumped Vulture has an average annual rate of decline of 43.9% between 2000-2007, whereas the combined average annual rate of decline of G. indicus and G. tenuirostris is over 16%. A complete ban on the use of diclofenac in livestock and the establishment of conservation breeding centres are suggested to prevent the extinction of these three species of vultures.
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... There are 23 vulture species in the world (16 Old world vulture and 7 New world vulture species) as shown in Table 1 (Prakash et al. 2003(Prakash et al. , 2007. In 1980s, Indian/Oriental white-backed vulture was thought to be the most common large bird of prey in the world with a population of tens of millions (Houston, 1985. ...
... It was reported that most of the Oriental Whiterumped and long-billed vultures found dead in the wild had suffered severe visceral gout (Prakash et al., 2007). Further, the simulation modelling results indicated that less than one percent of the livestock carcasses eaten by vultures need to contain levels of diclofenac lethal to vultures to cause the recorded rates of vulture populations decline across the India . ...
... 6 : Ban of Diclofenac in India and Punjab The National Board for Wildlife, India in a meeting on March 17, 2005, recommended a ban on veterinary use of diclofenac. Further, the license to manufacture the drug diclofenac was withdrawn by the Drug Controller General of India vide letter dated May 11, 2006 addressed to all the State Drug Controllers(Prakash et al., 2007). This directive was further strengthened in 2008, when the manufacture, sale or use of diclofenac f o r v e t e r i n a r y p u r p o s e s w a s m a d e a n imprisonable offence.The Punjab Government banned the use of Diclofenac for cattle w.r.t 29 April, 2005 to save the fast dwindling population of vultures in the region. ...
EDITORIAL Since times, vultures being 'keystone' scavengers play a critical role in nutrient cycling as they are positioned at the top of the food chain. They play major role in disposing off the carcasses of dead animals, both wild and domestic, along with other scavengers such as jackals, hyenas, dogs, crows and kites. Their adapted lifestyles ensured that no decaying carcasses remained. Thus, the vultures are most recognized scavengers which have ecological, economic & cultural significance. A decade ago, three species of South Asian vulture faced near-extinction because of widespread use of diclofenac to treat livestock, the carcasses of which were their main food source. According to the International Union for Conservation of Nature's (IUCN), 2015 Red List of threatened species, 9 species of vultures have been recorded from India. Out of these, 6 vulture species are threatened and further from these 6 Vulture species, 4 species are on the verge of global extinction. The near extinction species include, White-rumped/White backed Vulture (Gyps bengalensis), Long-billed Vulture/ Indian vulture (Gyps indicus), Red-headed vulture (Sarcogyps calvus) and Slender-billed Vulture (Gyps tenuirostris). A serious decline in the population of the main species of vulture has led to a series of meetings and seminars internationally including India in order to address the need for vulture conservation. The major initiatives taken to conserve vultures in India are, ban on the veterinary use of diclofenac drug, establishing vulture conservation breeding centres and vulture safe zones. However, a lot more needs to be done to save the diminishing populations of vulture and which requires an integrated approach of conservation breeding, research, monitoring and public awareness. The present issue is being published with as special focus on this magnificent bird, which not only fulfils a vital function in our ecosystem, but also a part of our culture. The article covers scientific classification, geographical range, phenotypic features, habits, ecological & cultural significance, present status & threats and initiatives being taken up for conservation of vultures throughout the world especially in India. It is hoped that information compiled in the newsletter will further enhance the knowledge of readers about vultures & motivate them to get involved in conservation, restoration and protection of vultures and their natural habitats.
... Without the threat of non-steroidal anti-inflammatory drugs like diclofenac, reasonable numbers of vultures are present on the MTR's Segur plateau (Ramakrishnan et al. 2010). Gyps vulture populations have declined dramatically in the Indian subcontinent over the last few decades, with the population estimated to be less than 5% of their previous size (Prakash et al. 2007; MoEFCC 2020). Estimating population distribution and abundance is critical for any conservation action. ...
... We also recorded 32 sighting records of the N. percnopterus over three years. Prakash et al. (2007; reported that N. percnopterus was recorded at the lowest levels in all road transect surveys, and this is a general trend throughout the NBR and the state of Tamil Nadu (Byju, Raveendran 2022). ...
Two resident and two local migratory vulture species are reported in the Mudumalai Tiger Reserve of the Nilgiri Biosphere Reserve. The early population estimates from the region are either scanty or crude. Vulture population estimation was performed using three different methods based on their breeding seasons and regional movements between 2019 and 2021. Road transect counts, nest counts, and carcass monitoring counts were used for population assessments. The road transect survey and nest site counting during the breeding season were conducted in all three years, while carcass monitoring was done in 2019 – 2020. For population estimation, three nest site colony counts were conducted for the resident Gyps bengalensis and for Gyps indicus. The other two methods, carcass monitoring and the road transect survey, were used for all four focal vulture species of the Mudumalai Tiger Reserve – Gyps bengalensis, Gyps indicus, Neophron percnopterus and Sarcogyps calvus. Significant variation in vulture population count was observed with different assessment methods.
... T he population of resident Gyps vultures crashed in the 1990s in the Indian Subcontinent (Prakash et. al. 2007). Following this, three resident Gyps vultures in India, namely the White-rumped-G. bengalensis, the Indian-G. indicus, and the Slender-billed Vulture G. tenuirostris were all listed as 'Critically Endangered' (IUCN 2013). The cause of the decline was the Non-steroidal Anti-Inflammatory Drug (NSAID) Diclofenac Sodium, which was used to t ...
The Indian Vulture (Gyps indicus) has declined across most of its range by over 95% since the mid-1990s due to which it has been listed as Critically Endangered by IUCN. The major cause of this decline is due to ingestion of the residues of nonsteroidal anti-inflammatory drug, diclofenac sodium which is present in the livestock carcasses. A small colony of these vultures has been observed in the Aurapani Range of the Achanakmar Tiger reserve situated in Lormi District of Chhattisgarh. We have monitored this colony between 2017 to 2020 where the number of active nests has increased from 4 to 9 in a span of four years. This is the first report of this vulture colony of Aurapani where the observations show an increase in the number of Indian Vultures. This area is very important for the sustenance of the colony as it is a unique habitat for the vultures providing them shelter throughout the year and an important nesting site.
... From being some of the most common large raptors in the world (Houston, 1985), three species of Gyps vultures endemic to south and south-east Asia were driven to near-extinction, due to unintentional poisoning by the veterinary non-steroidal anti-inflammatory drug (NSAID) diclofenac (Oaks et al., 2004;Shultz et al., 2004;Green et al., 2004;Prakash et al., 2007), and all are now classified as Critically Endangered in the IUCN Red List (BirdLife International, 2021). In India, the population of the worst-affected species, White-rumped Vulture G. bengalensis declined by 99.9% between the early 1990s and 2007, while that of Indian G. indicus and Slender-billed Vulture G. tenuirostris combined declined by 96.8% . ...
Population declines of Gyps vultures throughout South Asia were caused by unintentional poisoning by the NSAID diclofenac, which was subsequently banned. However, other vulture-toxic NSAIDs are available, including nimesulide, which, in experiments carried out in South Africa, was shown to be toxic to Gyps vultures. We report on safety-testing of nimesulide carried out on Himalayan Griffons G. himalayensis. We gave two vultures a dose of nimesulide by oral gavage at the maximum level of exposure, with two controls dosed with benzyl alcohol. In the two tested birds, plasma nimesulide concentrations peaked after six hours, while serum uric acid concentrations increased steadily up until 24 hours post-treatment, after which both birds died, displaying severe visceral gout. The control birds showed no adverse clinical or biochemical signs. We confirm that nimesulide is toxic to Gyps vultures. Veterinary use of nimesulide should be banned in all Gyps vulture range countries in the region.
Environmental contaminants are chemicals introduced intentionally or accidentally in our environments and have harmful impacts on biological systems. The adverse effects of environmental contaminants is one of the leading factors posing risk to the long-term conservation of wildlife worldwide. A high concentration of various environmental contaminants such as pesticides, industrial chemicals, pharmaceuticals, heavy metals, fertilizers, and beauty products are found in both aquatic and terrestrial wildlife habitats. Environmental contaminants such as diclofenac, Ivermectin, dichlorodiphenyltrichloroethane (DDT), mercury, lead, arsenic, bisphenol A, phthalates, oxybenzone, and 17α-ethinyloestradiol (EE2) have a significant toll on wild animals. The effects of contaminants can be acute, chronic, secondary, and/or indirect on wild animals. The drastic decline in the population of vultures in the Indian subcontinent is the most striking case to highlight the severity of contaminants on wild animals.KeywordsEnvironmentContaminantsWildlifePesticidesFertilizersPharmaceuticalsPCPsDDTDiclofenacImpact
Vultures are key to the functioning of ecosystems but they are assessed to be threatened globally and their numbers are at-risk due to changes in habitat and other factors. This study focuses on identifying localized conservation status changes in vultures over a decade (2011–2020) by assessing habitat occupancy and population in Uttar Pradesh using PRESENCE, GeoCAT and MaxEnt tools. The overall vulture population increased with differing growth rates across species (11–18%). The Extent of occupancy of Egyptian, Red-headed, and Indian vultures, and Himalayan Griffon increased over the decade but White-rumped and Cinereous vultures showed decrease in this parameter. The occupancy (ψ) and suitable area for Indian, White-rumped and Cinereous vultures decreased while, Egyptian and Red-headed vultures showed gains. Himalayan Griffon showed increased occupancy but decreased suitable area. On the other hand, Area of occupancy components showed improvement in conservation category in the case of Egyptian Vulture and Eurasian Griffon, but deterioration in Slender-billed Vulture. Remaining vultures (Cinereous, Himalayan Griffon, Indian, Red-headed and White-rumped) with continued threatened status were still a cause of concern. Overall, an increasing population coupled with decreasing suitable area indicated the concentration of individuals in smaller areas leading to enhanced extinction risks. This indicated that the imperiled resident Gyps (G. bengalensis, G. indicus and G. tenuirostris) were not recovering post-diclofenac-ban. However, an influx of population without nesting pressure in the wintering habitat indicated a positive future for migratory species. Therefore, management interventions for safeguarding the future of these vulnerable raptors should be concentrated in potentially suitable areas too as predicted in this study.
The White-rumped Vulture (Gyps bengalensis) is an accipitrid vulture native to Asia. Once known as the world's most abundant large bird of prey, its population declined dramatically across its range during the 1990s. As a result, it is listed on the International Union for the Conservation of Nature (IUCN) Red List as critically endangered. From 2010 to 2021, we monitored two breeding colonies of White-rumped Vultures in the Argha Important Bird and Biodiversity Area, Arghakhanchi District, in the western mid-hill region of Nepal. We visited the colonies at least three times in each breeding season during November, February, and April and calculated nesting success. We estimated annual trends in number of occupied nests (i.e., nesting activity, egg, nestling, or adult in incubation posture), number of fledglings, and productivity (i.e., young fledged per occupied nest). The number of occupied nests, fledglings, and productivity were analyzed separately using identical models. Although the number of occupied nests appeared to increase, the credible interval of the growth rate (r) overlapped zero (r = 0.05, 95% CRI =–0.06–0.16). The number of fledglings (r = 0.04, 95% CRI = –0.04–0.16) and productivity (r < 0.01, 95% CRI = –0.08–0.09) appeared stable. Our findings are encouraging because they suggest stable population and productivity levels in the two breeding colonies of this critically endangered bird. However, our survey covered a small portion of the global population over a single generation of the species. We recommend coordinated, widespread, and long-term monitoring of vultures across South Asia.
The population declines affecting Asian Gyps vultures are among the most rapid and geographically widespread recorded for any species. This paper describes the rates and patterns of mortality and population change over 4 years at three Oriental white-backed vulture Gyps
bengalensis colonies in Pakistan: Dholewala (initially 421 pairs), Toawala (initially 445 pairs) and Changa Manga (initially 758 pairs). Vulture mortality led to the extirpation of two of these colonies (Changa Manga and Dholewala) in 3 years, and a decline of 54.3% in the third. Visceral gout, indicative of diclofenac poisoning, was the largest single cause of death in vultures examined. Annual adult mortality from diclofenac poisoning was significantly positively correlated with annual population declines at each colony indicating a direct causal relationship. Visceral gout occurred in temporal and spatial clusters suggesting multiple point sources of diclofenac exposure. The spatial and temporal distribution of dead vultures and approximate time since death were used to estimate minimum rates at which colonies encountered carcasses with sufficient diclofenac to cause mortality of 1.26–1.88 carcasses per colony per month. By estimating total carcass consumption at each colony, the percentage of carcasses contaminated with diclofenac was calculated as 1.41–3.02%, exceeding the minimum required to have caused the observed population decline. With populations declining by approximately 50% annually, the long term survival of Gyps vultures in South Asia will require the removal of diclofenac from vulture food and establishment of captive populations for future restoration once the environment is free from contamination.
Rapid population declines of the vultures Gyps bengalensis , Gyps indicus and Gyps tenuirostris have recently been observed in India and Pakistan, continuing at least up to 2003. Surveys indicate annual rates of decline of 22–50% for G. bengalensis and G. indicus during 2000–03. Previous studies in Pakistan have shown that the non‐steroidal anti‐inflammatory drug diclofenac causes renal failure and is lethal to G. bengalensis when it feeds on the carcass of a domestic animal that received a normal veterinary dose shortly before death. In Pakistan, diclofenac poisoning was found to be by far the most frequent cause of death.
A simulation model of vulture demography, described in this paper, demonstrated that the observed rates of population decline could be caused by contamination with a lethal level of diclofenac in a small proportion (between 1 : 130 and 1 : 760) of ungulate carcasses available to vultures.
Proportions of adult and subadult vultures found dead or dying in the wild that had signs of diclofenac poisoning were similar to the proportions of deaths expected from the model if the observed population decline was due entirely to diclofenac poisoning. The proportion of the excess mortality required to cause the observed population declines that could be attributable to diclofenac was estimated to be between 71% and 100%, depending on model assumptions. However, across all or most of the plausible range of assumed values for adult survival, the upper 95% confidence limit for the proportion of excess mortality due to diclofenac was 100%. Hence, available data are consistent with diclofenac poisoning being at least the major cause, and possibly the only cause, of rapid population declines of Gyps vultures across the Indian subcontinent.
Synthesis and applications . We recommend that urgent action is taken in the range states of the three currently threatened vulture species to prevent the exposure of vultures to livestock carcasses contaminated with diclofenac. Research is also needed to identify alternative drugs that are effective in livestock and safe for vultures. Efforts should also be made to raise awareness, among veterinarians, pharmacists, livestock owners and the general public, of the problem of diclofenac contamination and the availability of safe alternatives. Captive holding and breeding of vultures until diclofenac is controlled is recommended as a precaution to ensure the long‐term survival of the threatened species and to provide a stock of birds for future reintroduction programmes.
In 2000, we conducted a survey to quantify the declines in the populations of Gyps bengalensis and G. indicus across India since 1990–1993. Directly comparable data for the two periods were obtained from over 6000 km of road transect surveys carried out in protected areas, the regions around protected areas and linking highways across the country. An additional 5000 km were covered in 2000 in previously unsurveyed areas. Further data were collected from questionnaires circulated to ornithologists, wildlife experts and forestry officials. Massive declines in the populations of both species were apparent from all parts of the country, and exceeded 92% overall. The extent of declines did not differ between protected areas and elsewhere. Apparently sick birds, with drooping necks, were observed in all regions, and dead adult and juvenile vultures were frequently observed. Food availability did not decline greatly over this period. The patterns of declines and the presence of sick and dead birds indicate epidemic disease as a possible cause. If so, this is likely to be an agent to which the population is naı̈ve, e.g. an introduced agent or one from which the species were previously isolated. Immediate steps are needed to confirm this and to identify measures that could be taken to stem the problem.
Recent declines in the populations of three species of vultures in the Indian subcontinent are among the most rapid ever recorded in any bird species. Evidence from a previous study of one of these species, Gyps bengalensis, in the Punjab province of Pakistan, strongly implicates mortality caused by ingestion of residues of the veterinary non-steroidal anti-inflammatory drug diclofenac as the major cause of the decline. We show that a high proportion of Gyps bengalensis and G. indicus found dead or dying in a much larger area of India and Nepal also have residues of diclofenac and visceral gout, a post-mortem finding that is strongly associated with diclofenac contamination in both species. Hence, veterinary use of diclofenac is likely to have been the major cause of the rapid vulture population declines across the subcontinent.
Gyps vulture populations across the Indian subcontinent are declining rapidly and evidence indicates that veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac is the major cause. Exposure of vultures to diclofenac is likely to arise from the consumption of livestock carcasses that have been treated shortly before death, however, detailed information regarding the prevalence and residual levels of diclofenac in carcasses available to vultures in India remains unreported. Here, we present data on diclofenac residues in 1848 liver samples taken from carcasses of dead livestock sampled at 67 sites in 12 states within India, between May 2004 and July 2005. Diclofenac residues were detected in carcasses in all states except Orisa, where only one site was sampled. The overall prevalence of detectable diclofenac (>10 microg kg(-1)) across all states was 10.1% and varied significantly among states, with up to 22.3% prevalence determined in Bihar. The geometric mean concentration of diclofenac found in samples in which the drug was detected was 352 microg kg(-1). The prevalence of carcasses containing diclofenac is similar to that previously proposed to be required to have caused the observed Gyps vulture declines in India. On the 11th of May 2006, the Drug Controller General (India) ordered the withdrawal of all licenses granted for the manufacture of diclofenac for veterinary use within India. However, if Gyps vultures are to be protected, potentially substantial existing stocks now need to be quickly and effectively removed from the Indian veterinary market.
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