Today saw a glimmer of hope for the three species of Asian vulture threatened with extinction.
Oriental white-backed, long-billed, and slender-billed vultures in South Asia have suffered one of the most rapid and widespread population declines of any bird species, declining by more than 97% over the last 10-15 years.
These declines were caused by the widespread veterinary use of the drug diclofenac for the treatment of sick domestic livestock throughout the Indian subcontinent. Diclofenac kills vultures that feed on the bodies of livestock that have been given the drug shortly before death.
To combat diclofenac's devastating effects on vulture populations, the Indian government announced, in March 2005, its intention to phase out the use of the drug. However, progress has been hampered by the lack of an alternative drug that is known to be safe for vultures yet effective for treating livestock.
In a new report published in the open access journal PLoS Biology, a team of scientists from South Africa, Namibia, India, and the UK concluded that such an alternative has now been found.
The team, led by Gerry Swan of the University of Pretoria, found that the drug meloxicam was safe to vultures at the likely range of levels they would be exposed to in the wild. Meloxicam, which is similar to diclofenac in its effectiveness for treating livestock, has recently become available for veterinary use in India and could easily be used in place of diclofenac.
"This research is an excellent example of international collaboration in response to an urgent conservation problem," Said Dr Debbie Pain, Head of International Research at the RSPB and a co-author of the paper.
Fellow-author Dr Rhys Green, Principal Research Biologist at the RSPB and a scientist at Cambridge University, said: "Dr Lindsay Oaks discovered that diclofenac is the cause of the vulture declines just two years ago, so having found a practical solution so quickly is encouraging. Even so, vulture populations are declining so fast that it could still be too late to save them unless action is taken immediately."
Publication of these results is very timely because the government of India today convened a two-day international meeting to decide how to save the endangered vultures. Removal of diclofenac from their food supply is a vital step, so the identification of an alternative drug may have come just in time.
Dr Asad Rahmani, Director of the Bombay Natural History Society said: "It is essential that the government of India acts quickly to make good use of this new information. Diclofenac must be replaced by meloxicam as soon as possible and there are many things that government can do to speed this up."
The vulture declines have had profound ecological and social consequences. Vultures play a vital role in environmental health by disposing of carcasses and reducing the risk of disease.
The two key steps necessary to save vultures from extinction are removal of diclofenac from their food chain, and the establishment of conservation centres for captive breeding as a stop-gap measure until that is achieved.
"It is essential that the environment is free of diclofenac before vultures from conservation breeding centres can be released into the wild," said RSPB Research Biologist Dr Richard Cuthbert, who coordinated the new research. "In view of these findings, there is now no reason for governments to delay in banning the veterinary use of diclofenac."
Citation: Swan G, Naidoo V, Cuthbert R, Green RE, Pain DJ, et al. (2006) Removing the threat of diclofenac to critically endangered Asian vultures. PLoS Biol 4(3): e66.
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The three endangered vulture species are found only in South Asia. In addition to populations in India, Pakistan, and Nepal, there are small numbers in Myanmar, Bangladesh, Bhutan, and Cambodia.
There are thought to have been tens of millions of Asian vultures before diclofenac was used to treat livestock. The Critically Endangered oriental white-backed vulture was considered to be probably the most common large bird of prey in the world in the 1980s, prior to diclofenac use.
Vultures are declining by between 22 and 48% each year in India. They die within days of consuming flesh from the carcasses of diclofenac-treated cattle and water buffaloes.
Less than 1% of the Indian population of the oriental white-backed vulture and less than 3% of long-billed vultures remain. The slender-billed vulture is the least common of the three.
The IUCN – World Conservation Union has classed all three Asian vulture species as Critically Endangered, the category most at risk of extinction in the near future.
Feral dogs are now a major scavenger of wild and domestic animal carcasses. This could increase the risk to humans of contracting rabies, which is mainly transmitted through dog bites.
The research involved administering meloxicam to African white-backed vultures by oral ingestion, and subsequently by feeding them with tissues from cattle treated shortly before death with meloxicam. A small number of Oriental white backed and long billed vultures were also given meloxicam by oral ingestion.
Only a small proportion of diclofenac production is for veterinary use. Use of diclofenac as a painkiller by humans would not be affected if use in livestock were banned.
Captive breeding and release of a related species, the Eurasian griffon vulture, led to a thriving wild population being re-established in the Cevennes region of France, from which the species had been wiped out by persecution.
Because vulture populations across the Indian subcontinent are now so low, both a veterinary ban on the use of diclofenac and the taking of vultures into captivity for conservation breeding programmes are necessary to save these species from extinction. The Bombay Natural History Society, the RSPB and others have established two vulture breeding centres. These are in Pinjore, Haryana, and at the Buxa Tiger Reserve in West Bengal. Vultures and their offspring will be housed here until the environment is diclofenac-free, when they will be reintroduced to the wild. Chris Bowden heads the RSPB's vulture conservation programme.
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