New study gives hope for critically endangered birds, but more work to be done
May 2011: The ban on a veterinary drug which caused an unprecedented decline in Asian vulture populations has shown the first signs of progress, according to scientists. However, the recovery of the wild vulture populations needs the drug completely removed from the birds' food supply.
Now researchers report measurements of the prevalence and concentration of diclofenac in carcasses of domesticated cattle in India, before and after the implementation of the ban.
The governments of India, Nepal and Pakistan banned the veterinary use of the painkiller diclofenac in 2006 because of its lethal effects on vultures that feed on the carcasses of cattle and buffaloes treated with the drug.
Vulture survival depends on drug eradication being more successful
The study shows that the proportion of cattle carcasses in India contaminated with the drug declined by more than 40 per cent between 2006 and 2008. The concentration of the drug in contaminated animals also fell.
Combining the effects of these two changes, the expected rate of annual population decline of the vultures is expected to slow by around two thirds. Yet this is still expected to be around 18 per cent per year for the most susceptible species, the oriental white-backed vulture, down from about 40 per cent per year before the ban, meaning that vultures will not recover unless efforts to eradicate the drug become more successful.
Although the legal action has started to show encouraging results, much remains to be done, because diclofenac manufactured for human use is still being used illegally to treat cattle in India.
Even some alternative drugs are toxic to vultures
One of the study's authors, Dr Devendra Swarup, former Research Director of the Indian Veterinary Research Institute, commented: ‘Because of the difficulty in ensuring that human diclofenac is not being used illegally, testing the vulture food directly is the only way to find out how safe the vultures really are.'
Lead author, Dr Richard Cuthbert of RSPB, said: ‘This shows how much progress has been made, but there is still a job to do to make sure that safe alternative drugs are used. Unfortunately some of the alternatives have not been tested for their safety to vultures and one drug in increasing use, ketoprofen, is already known to be toxic to vultures.'
The only safe alternative used in India is meloxicam, which is becoming more widely used now that its cost is falling and approaching that of diclofenac. However, other drugs known to be toxic or with unknown effects remain legal and are still being used by vets.
Dr Asad Rahmani, director of the Bombay Natural History Society said: ‘Complete removal of diclofenac from vulture food is the single most important action needed to save vultures. Human formulations are still being sold by some irresponsible companies in large veterinary-sized vials and these bigger bottles must also be outlawed to make illegal diclofenac use on cattle more difficult and expensive.'
News source -
http://www.wildlifeextra.com/go/news/vulture-deaths.html
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