Asian Vulture Research Articles

Vulture restaurants and their role in reducing diclofenac exposure in Asian vultures

The provision of supplementary food at vulture restaurants is a well-established tool in the conservation of vulture species. Among their many applications, vulture restaurants are used to provide a safe food source in areas where carcasses are commonly baited with poisons. Rapid and extensive declines of vultures in the Indian subcontinent have been attributed to the toxic effects of diclofenac, a pharmaceutical used in the treatment of livestock, to which vultures are exposed while feeding on the carcasses of treated animals. A vulture restaurant was established at the Oriental White-backed Vulture Gyps bengalensis colony at Toawala, in Punjab province Pakistan, to test the effectiveness of the technique in modifying ranging behaviour and mortality at the colony. Six male vultures were fitted with satellite transmitters to describe variation in movement and home-range during periods when safe food was alternately available and withheld at the vulture restaurant. There was considerable variation in individual home-range size (minimum convex polygons, MCP, of 1,824 km2 to 68,930 km2), with birds occupying smaller home-ranges centred closer to the restaurant being more successful in locating the reliable source of food. Fixes showed that 3 of the tagged vultures fed at the vulture restaurant and the home-range of each bird declined following their initial visit, with a 23–59% reduction in MCP. Mean daily mortality during provisioning was 0.072 birds per day (8 birds in 111 days), compared with 0.387 birds per day (41 birds in 106 days) during non-provisioning control periods. Vultures tended to occupy greater home-ranges, cover greater distances each day and spend proportionately more time in the air during the late brooding and post-breeding seasons. Attendance at the vulture restaurant also declined during this period with fewer birds visiting less often and no tagged vultures visiting the vulture restaurant at all. These findings indicate that vulture restaurants can reduce, but not eliminate, vulture mortality through diclofenac exposure and represent a valuable interim measure in slowing vulture population decline locally until diclofenac can be withdrawn from veterinary use.

Collapse of Asian vulture populations: risk of mortality from residues of the veterinary drug diclofenac in carcasses of treated cattle

Summary The populations of three species of South Asian vultures (Gyps bengalensis, Gyps indicus and Gyps tenuirostris) have declined rapidly within the last decade and all are now critically endangered. Veterinary use of the non‐steroidal anti‐inflammatory drug diclofenac appears to be a major cause of the declines. Vultures are likely to be exposed to the drug when they feed on carcasses of livestock that were treated with diclofenac before death. We measured the concentration of diclofenac in the tissues of treated Indian humped and European cattle (Bos indicus and Bos taurus) in relation to the interval between dosing and death. We used a dose–response model to assess the risk posed to wild vultures if they feed on carcasses of treated livestock. Diclofenac concentrations in fat, intestine, kidney and liver were considerably higher than those in muscle, but concentrations in the first four tissues initially depleted more rapidly (half‐life 6–8 h) with time since the last injection of the drug, compared with muscle (half‐life 15 h). Depletion rates became much slower in all tissues 25–98 h after the last injection. Diclofenac concentration, averaged across the carcass, was enough to cause appreciable mortality (> 10% of birds per meal) if oriental white‐backed vultures G. bengalensis were to take a large meal from the carcass of an animal that was given its last dose of the drug within a day or two before death. Vultures that feed selectively on tissues with high concentrations of the drug, such as kidney, liver and intestine, would be exposed to a higher risk and for longer after dosing. Synthesis and applications. The tissues of cattle treated with diclofenac are a hazard to wild vultures that feed on an animal that dies within a few days after treatment. Intestine, kidney and liver have the highest diclofenac concentrations, but the concentration averaged across all the edible tissues of the carcass is also hazardous. Withdrawal of diclofenac from veterinary use on animals whose carcasses may become available to scavenging vultures is recommended. In ex situ and in situ conservation projects, vultures should be fed on carcasses of animals that are known not to have been treated with diclofenac in the week before death.

Decline of Vultures in Asia

The random samples item “Vulture Culture” (3 Feb., p. [587][1]) presents the appearance of large numbers of Eurasian griffon vultures in Rajasthan, India, as good news, but this is far from the case. In India, populations of three species of vultures endemic to South Asia (oriental white-backed, long-billed, and slender-billed) have declined to less than 3% of what they were about a decade ago and the decline continues ([1][2]). The Eurasian griffons are mostly immature birds from Central Asia, Tibet, and Mongolia that return there to breed, probably attracted in larger numbers by plentiful supplies of livestock carcasses left uneaten now that the resident species have almost disappeared. There is now substantial published evidence that the cause of the Asian vulture decline is veterinary use of the drug diclofenac, which vultures take in when they feed on the carcass of a cow or water buffalo treated with the drug ([1][2]–[3][3]). Eurasian griffons are as susceptible to kidney failure caused by diclofenac as their Asian relatives ([4][4]), so it is likely that the source populations of this species that winter in India will also be affected. Such an effect will not be detected soon, however, because there is virtually no systematic monitoring of numbers of vultures breeding in these inaccessible areas. Numbers of immature Eurasian griffons wintering in India may continue to grow, but this will probably just indicate a growing drain on their source populations. A ban on the veterinary use of diclofenac, announced by the Indian prime minister in March 2005 ([5][5]), will therefore probably benefit Eurasian griffons as well as the resident species, but only if it can be implemented successfully. The Random Samples item also contained inaccuracies about recently published findings on the safety to vultures of meloxicam, an alternative to diclofenac that could help to save the vultures by speeding the removal of diclofenac from their food supply ([6][6]). The vultures used in the experiments were captive, but not captive-bred, and 72 birds (not 35) were treated, of which 66 were given meloxicam itself, rather than meat from treated cattle. 1. 1.[↵][7]1. R. E. Green 2. et al. , J. Appl. Ecol. (2004)41, 793. 2. 2.1. J. L. Oaks 2. et al. , Nature (2004)427, 630. 3. 3.[↵][8]1. S. Shultz 2. et al. , Proc. R. Soc. London Ser. B (Suppl.) (2004)271, S458. DOI 10.1098/rsbl.2004.0223. 4. 4.[↵][9]1. G. E. Swan 2. et al. , Biol. Lett. (2006)doi:10.1098/rsbl.2005.0425 9. 5. 5.[↵][10]1. P. Bagla , Science (2005)307, 1851. 6. 6.[↵][11]1. G.E. Swan 2. et al. , PloS Biol. (2006)4 (no. 3), e66. [1]: /lookup/doi/10.1126/science.311.5761.587a [2]: #ref-1 [3]: #ref-3 [4]: #ref-4 [5]: #ref-5 [6]: #ref-6 [7]: #xref-ref-1-1 View reference 1. in text [8]: #xref-ref-3-1 View reference 3. in text [9]: #xref-ref-4-1 View reference 4. in text [10]: #xref-ref-5-1 View reference 5. in text [11]: #xref-ref-6-1 View reference 6. in text

Removing the Threat of Diclofenac to Critically Endangered Asian Vultures

Veterinary use of the nonsteroidal anti-inflammatory (NSAID) drug diclofenac in South Asia has resulted in the collapse of populations of three vulture species of the genusGyps to the most severe category of global extinction risk. Vultures are exposed to diclofenac when scavenging on livestock treated with the drug shortly before death. Diclofenac causes kidney damage, increased serum uric acid concentrations, visceral gout, and death. Concern about this issue led the Indian Government to announce its intention to ban the veterinary use of diclofenac by September 2005. Implementation of a ban is still in progress late in 2005, and to facilitate this we sought potential alternative NSAIDs by obtaining information from captive bird collections worldwide. We found that the NSAID meloxicam had been administered to 35 captiveGyps vultures with no apparent ill effects. We then undertook a phased programme of safety testing of meloxicam on the African white-backed vultureGyps africanus, which we had previously established to be as susceptible to diclofenac poisoning as the endangered AsianGyps vultures. We estimated the likely maximum level of exposure (MLE) of wild vultures and dosed birds by gavage (oral administration) with increasing quantities of the drug until the likely MLE was exceeded in a sample of 40G. africanus. Subsequently, sixG. africanus were fed tissues from cattle which had been treated with a higher than standard veterinary course of meloxicam prior to death. In the final phase, ten Asian vultures of two of the endangered species(Gyps bengalensis,Gyps indicus) were dosed with meloxicam by gavage; five of them at more than the likely MLE dosage. All meloxicam-treated birds survived all treatments, and none suffered any obvious clinical effects. Serum uric acid concentrations remained within the normal limits throughout, and were significantly lower than those from birds treated with diclofenac in other studies. We conclude that meloxicam is of low toxicity toGyps vultures and that its use in place of diclofenac would reduce vulture mortality substantially in the Indian subcontinent. Meloxicam is already available for veterinary use in India.

Switching Drugs for Livestock May Help Save Critically Endangered Asian Vultures

In just ten years, tens of millions of vultures have vanished from the Indian subcontinent. Since the early 1990s, white-backed (Gyps bengalensis), long-billed (G. indicus), and slender-billed (G. tenuirostris) vulture populations have dropped by over 95%. In Europe, it was clear that human persecution eradicated bearded and griffon vultures from some countries (reintroduction and protection efforts are now restoring populations). But in India, where it is illegal to kill wildlife and the bird is valued for its ecological role, their unprecedented decline was puzzling. Dead birds found in India, Pakistan, and Nepal had extensive visceral gout (a buildup of uric acid crystals in the internal organs associated with renal failure). The birds often appeared sick and lethargic, some showed prolonged severe neck drooping, before collapsing—sometimes from their perches.

Diclofenac residues as the cause of vulture population decline in Pakistan.

The Oriental white-backed vulture (OWBV; Gyps bengalensis) was once one of the most common raptors in the Indian subcontinent. A population decline of >95%, starting in the 1990s, was first noted at Keoladeo National Park, India. Since then, catastrophic declines, also involving Gyps indicus and Gyps tenuirostris, have continued to be reported across the subcontinent. Consequently these vultures are now listed as critically endangered by BirdLife International. In 2000, the Peregrine Fund initiated its Asian Vulture Crisis Project with the Ornithological Society of Pakistan, establishing study sites at 16 OWBV colonies in the Kasur, Khanewal and Muzaffargarh-Layyah Districts of Pakistan to measure mortality at over 2,400 active nest sites. Between 2000 and 2003, high annual adult and subadult mortality (5-86%) and resulting population declines (34-95%) (ref. 5 and M.G., manuscript in preparation) were associated with renal failure and visceral gout. Here, we provide results that directly correlate residues of the anti-inflammatory drug diclofenac with renal failure. Diclofenac residues and renal disease were reproduced experimentally in OWBVs by direct oral exposure and through feeding vultures diclofenac-treated livestock. We propose that residues of veterinary diclofenac are responsible for the OWBV decline.

Asian Vultures Killed by Mystery Disease

Asian Vultures Killed by Mystery Disease

Pain of Extinction: The Death of a Vulture

In the mid-1990s it was discovered that populations of three species of Asian vulture were disappearing at an unprecedented rate throughout India and the surrounding region. In attempting to convey the gravity of this situation we are often drawn to present it through numbers and data, to recount, for example, that 99 per cent of the Oriental white-rumped vultures (Gyps bengalensis) are now gone. But is this an appropriately ethical response to the mass death of vultures and the likely extinction of their species? In contrast to these more conventional accounts of extinctions, this article takes up the pain of vultures and the claim for response and responsibility that this pain issues. Writing about pain brings individual vultures (and others) back into our accounts as ethical subjects. But inside the multispecies communities of life that we all inescapably inhabit, I argue that this responsibility requires a worldliness beyond discrete individuals, and consequently must be understood as a generative opening, drawing us into entangled accountabilities.