Assam’s rare captive-bred vultures face a drug problem

The last of the nature’s scavengers in Assam, a suitable habitat for vultures, are battling toxic chemicals in livestock carcasses. And the ‘meal of death’ that is killing them is also delaying freedom for vultures being reared in captivity in the State.

The Vulture Conservation Breeding Centre (VCBC) at Rani, about 30 km west of Guwahati, is one of four in India that the Bombay Natural History Society (BNHS) set up more than a decade ago in association with State Forest Departments.

The VCBC has 104 vultures, most of them brought in as chicks from the wild. The centre has 30 adults and sub-adults: all oriental white-backed and slender-billed. These are two of six species found in Assam that are old enough to be set free.

But their release is getting delayed because big vials of diclofenac, a painkiller, banned three years ago but allowed to be sold if manufactured before December 2015, are yet to expire. Rampant use of pesticides by farmers and more than 70,000 tea gardens is another cause.

The digestive system of vultures, experts say, is so evolved that they can tolerate bacteria and natural toxins in putrefying meat. But they are vulnerable to chemicals such as diclofenac, present in the carcasses of cattle that were injected with the painkiller.

Spelling doom

“Diclofenac for veterinary use was banned in 2005, but vials for humans continued to be made until BNHS pressured the government into banning those of 30 ml or more in 2015. Humans need 3-5 ml while only 30 ml or more works for cows. But quacks use the 30 ml vials for veterinary use, with fatal consequences for vultures,” Sachin Ranade, the Rani centre manager, told The Hindu .

The centre, according to Mr. Ranade, is unlikely to release the adult vultures until the last of the 2015 stocks of the big vials expire by December 2018. Even then, there is no guarantee that the birds will be safe.

This is because of easy availability of pesticides. Wildlife officials say dogs, jackals and leopards are usually the target of villagers who lace the carcass of dead cattle with pesticides. But vultures are the unintended victims. On March 18, at least 32 vultures, most of them Himalayan griffons, died after feeding on the carcass of a goat.

The VCBC, however, is making all efforts to save the birds. For instance, mutton is the only food given at the VCBC and goats are kept for 10-12 days before the feeding. This is to ensure that traces of any toxic painkiller or other chemicals are flushed out.

India hosts nine vulture species, five of them the highly endangered Gyps species. Assam is home to six, including winter visitors from the Himalayas — the Himalayan and Eurasian griffons.

BNHS and other organisations found in the 1990s that the Gyps populations in India and Nepal declined from about 40 million by 99.9% in just two decades.

Vultures take time to mature, pair for life, breed once a year, and live up to 70 years – making captive breeding efforts a challenge, and their decline serious.

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Printable version | Sep 28, 2022 10:05:12 pm | https://www.thehindu.com/sci-tech/energy-and-environment/assams-rare-captive-bred-vultures-face-a-drug-problem/article23343814.ece