Why are vultures dying?

Published: Monday 31 December 2007

Down to Earth The anti-inflammatory drug diclofenac has been incriminated as the main cause for decline in vulture numbers in South Asia. The birds, it is said, perish after feeding on carcasses that have residues of the drug. The argument seems logical but is not based on scientific evidence. The diclofenac-toxicity argument, in fact, obscures a deeper malaise in vulture conservation: a shortage of skilled hands and a lack of seriousness.

The fall in vulture population predates the introduction of diclofenac: the drug was introduced in South Asia in 1994. But a fall in vulture numbers was reported as early as the 1960s in Kerala and 1981 in Andhra. The vulture population is falling in Africa as well where diclofenac is hardly used. Many experts reject the role of pesticides and viral diseases as reasons for the decline.

Diclofenac has been found to be less dangerous to large vultures of the genus Gyps: the Eurasian griffon and Himalayan griffon, for example. It is not clear why. It also appears that the drug is non-toxic to crows, dogs and other scavengers that feed on carcasses.

Zeroing in In 2003-2004, scientists led by Lindsay Oaks of the Department of Veterinary Microbiology, Washington State University, fed 20 vultures in Pakistan carcasses of buffaloes which had been given diclofenac. Thirteen died. But the scientists had nothing to say on how seven survived.

Diclofenac's half life is just 12.2 hours and the drug retains its effects up to 71 hours in the kidneys and liver of livestock. So, it is very likely that by the time the carcasses reach dumping sites, diclofenac has lost its potency.

How many birds exactly Some studies suggest there has been a 95-97 per cent fall in vultures in the past decade. This estimate was made after analyzing road surveys for vultures in 1990-93 and in 2000. But do we have a detailed ecological analysis to find out why 3-5 per cent vultures survived? I recently spotted about 5,000 vultures belonging to seven species in Rajasthan and Gujarat. These include the long-billed vulture, white-backed vulture, king vulture, the Egyptian vulture, the migratory Himalayan griffon and the cinereous vulture. Many researchers have also spotted several small to large vultures at many locations in central, western and northern India.

Our research has shown that in the last decade, habitat loss due to massive mining, quarrying, blasting and logging have affected vultures in Rajasthan and Gujarat. Nesting and roosting sites of vultures have also declined. Other reasons include scarcity of food and water, predation by wild dogs and accidents. Changes in agriculture, livestock rearing land use practices have also affected vultures' breeding ecology.

It is important to study the genetic diversity of all Gyps vulture in India to ascertain if there has been a loss of genetic diversity, leading to a decline in vulture population.

Captive breeding Authorities must plan well while selecting the breeding stock for captive breeding. Birds most suitable for the purpose should be selected, rather than unsystematically and unscientifically collecting chicks from their natural habitat, disturbing natural breeding.

The Union Ministry of Environment and Forests has, with assistance from the Bombay Natural History Society, the Royal Society for the Protection of Birds and the Zoological Society London, started captive breeding centres at Pinjore in Haryana and Buxa in West Bengal. However, no Indian organization has expertise in captive breeding and there are already problems because of a lack of skilled hands. Temperature fluctuations led to the death of two nestlings in Pinjore in January this year.

The Central Zoo Authority is, however, unfazed. It is going ahead with its plan for four more captive breeding centres in Junagarh, Bhopal, Hyderabad and Bhubaneswar.

Extensive statewide, scientific surveys need to be conducted to ascertain the most vulnerable vulture species. Captive breeding must then be dedicated to conserving these species.

Sadly, no such measure has been initiated so far. But then captive breeding should not be the only way to conserve vultures. My team has saved more than 30 long-billed and white-romped vultures in the last two years in Rajasthan and Gujarat. I am quite certain that a countrywide rescue programme can save over 100 threatened vultures every year. This is something which an expensive captive breeding programme will not be able to match in the next 10-15 years.

Anil Chhangani is member, iucn Birds and Mammals Breeding Specialist Group. He can be reached at chhanganiak@yahoo.com

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