Back from the brink

Back from the brink


All set to take off : The long-billed vulture. The ban seems to have worked. Five years ago, India, Pakistan and Bangladesh banned veterinary use of diclofenac as it was found to be the main causative factor behind a virtual wipe-out of the subcontinent’s vultures that gorged on diclofenac-laden carcasses. Scientists have now unearthed the first evidence of the efficacy of the ban.

The ban did not have an immediate impact, but started to show results after almost three years. Analysis of samples collected around December 2008 showed a reverse trend in the decline of vulture population. Even though veterinary diclofenac is still believed to be in the system illegally, the results so far are encouraging.

Researchers at Bombay Natural History Society reported decline of vulture population first in the 1990s in Keoladeo National Park at Bharatpur in Rajasthan.

Subsequently, the crash in population was reported from across the country.

A large number of studies in the last decade have clearly established that the population of three species of vultures decreased at an alarming rate, thanks to the drug. A meeting of the Indian National Board for Wildlife in 2005, chaired by the Prime Minister of India, finally prompted the withdrawal of licences for the manufacture of veterinary diclofenac.

The numbers of oriental white-rumped vultures (gyps bengalensis) declined by 99.9 per cent between 1997 and 2007. The population of oriental white-billed vultures has an average annual rate of decline of 43.9 per cent between 2000 and 2007. Their numbers are on a decline since 1992, as a result of which India now has only about 11,000 birds from tens of millions.

Populations of long-billed and slender-billed vultures have fallen. The combined population of long-billed vultures (gyps indicus) and slender-billed vultures (gyps tenuirostris) too dropped by 96.8 per cent. With a combined annual average decline rate of 16 per cent, India currently has about 45,000 long-billed vultures and just about 1,000 slender-billed vultures.

Just short of extinct

All three species fall in the International Union for the Conservation of Nature (IUCN) category of ‘critically endangered’, the highest risk category is just short of extinct. Researchers from BNHS and Indian Veterinary Research Institute, Izzatnagar with colleagues from UK and Spain measured the prevalence and concentration of diclofenac in carcasses of domesticated cattle in India, before and after the implementation of the ban. Samples were collected in three phases – between May, 2006 and July, 2005; April and December of 2006 and between January, 2007 and December, 2008. The study shows that the proportion of cattle carcasses in India contaminated with the drug declined by over 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 approximately 60 per cent, the team reported in the journal PLOS One on May 11.

Need for greater efforts

The resulting decline rate is still expected to be around 18 per cent per year for the most susceptible species, the oriental white-backed vulture. Even though the results show early signs of success compared to the pre-ban era when the decline was about 40 per cent per year, the study suggests that vultures will not recover unless more efforts are made to eradicate the drug from the system. Although legal action has started to show encouraging results, much remains to be done.

“Because of the difficulty in ensuring that human diclofenac is not being used illegally and in secret, testing the vulture food (cattle carcasses) directly is the only way to find out how safe the vultures really are,” said Devendra Swarup, former research director at IVRI and one of the authors of the paper.

Three captive breeding centres have been built so far in India, where 250 vultures are housed at the moment and successfully breeding of all three species is continuing. The centres are in Haryana, West Bengal and in Assam. Two additional centres are operational in Nepal and Pakistan, and five Indian zoos are also developing captive breeding facilities with the support of the Central Zoo Authority.

“We will start releasing the vultures by 2014-15 when we have sufficient birds (in groups of 25 birds) and most importantly by that time, the government should see that diclofenac is totally removed from the veterinary sector; otherwise these released birds will also die one day due to diclofenac poisoning,” BNHS director Asad Rahmani told Deccan Herald. Pharmacies in India often dispense both human and veterinary medicines because of which they can legally hold diclofenac stocks.

Safe alternatives are key

They dispense human formulations of diclofenac for use on livestock. Together with informal and illegal dispensing of human diclofenac for veterinary purposes by unregistered people probably accounts for the continued contamination of ungulate carcasses, the researchers said, adding that a similar situation might exist in the Punjab province of Pakistan too.

Complete removal of diclofenac from vulture food was the single most important action needed to save vultures, Rahmani 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,” said the study’s lead author Richard Cutbert from Royal Society for the Protection of Birds.

The only safe alternative used in India known so far is meloxicam, which is becoming more widely used now that its cost is falling and approaching that of diclofenac, Rahmani added.