This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
India's three vulture species have all but disappeared from the country's skies. Over the last 20 years, virtually all of India's vultures have died, the victims of unintentional poisoning. Vultures feed on dead cattle and other livestock that had been treated with an anti-inflammatory drug called diclofenac, which sends vultures into renal failure. Unfortunately, the cause of the vulture declines wasn't discovered until 2004, long after vulture populations had already been devastated.
Now India's attempts to save one of its vulture species, the slender-billed vulture (Gyps tenuirostris), has marked its first success. According to a report from the Press Trust of India (PTI), "A chick born in February last year from one of the six pairs of the rare species hosted in the vulture conservation breeding center at Rajabhatkhawa forest in West Bengal's Jalpaiguri district is now healthy."
The program, operated by the Bombay Natural History Society, is currently raising 23 adult and juvenile slender-billed vultures that have been caught and removed from the wild over the last four years. Fewer than 200 mated pairs of the birds are estimated to still exist in the wild. If enough birds can be raised in captivity, they will be released into the wild to augment remaining populations, although that step may still be years away.
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The conservation program also hosts 19 long-billed (Gyps indicus) and 49 white-backed (Gyps africanus) vultures, and aims to create "founder populations" of 25 pairs for each of the three species.
The mass vulture die-offs have had terrible consequences throughout India. With no vultures to eat cattle carcasses (which are just dumped when the cows die), other predators have filled the gap. Populations of feral dogs have exploded in recent years, adding 5.5 million more canines to the streets. A report published last year in the journal Ecological Economics suggests this massive increase in feral dogs has led to tens of millions of attacks on humans and as many as 47,300 human deaths from rabies.
India banned the veterinary form of diclofenac in 2006, but vets and farmers just switched to using the version of the drug intended for humans, and vulture populations continue to decline as much as 40 percent a year, according to PTI. Even the smallest use of diclofenac in India threatens future vultures; according to BirdLife International, computer modeling has shown that vultures will continue to die at current rates if just one in 760 livestock carcasses contains diclofenac residues.
Image: Slender-billed vulture in captive-breeding program, by Dave Dick, BirdLife International