Vultures may be rescued by their genetic diversity

A DNA analysis of 153 vultures caught from the wild for captive breeding centres of Bombay Natural History Society revealed that a large proportion was unrelated and that possibility of inbreeding was low.

India’s notoriously diminished vulture population, now just 3 per cent of its size from two decades ago, may in fact have a fighting chance of revival, says a new research paper. What vultures have lost in numbers, they make up for in genetic diversity — a key criterion for successful breeding — finds a study of three critically endangered Asian vultures: Oriental White-backed vulture (Gyps bengalensis), Long-billed vulture (Gyps indicus) and Slender-billed vulture (Gyps tenuirostris).

A DNA analysis of 153 vultures caught from the wild for captive breeding centres of Bombay Natural History Society revealed that a large proportion was unrelated and that possibility of inbreeding was low. The results were published in the journal Animal Conservation.

The genetic data from these captive populations indicate that there is no difference in levels of their genetic diversity prior to or after their decline, lead author Farah Ishtiaq of the Centre for Ecological Sciences, Indian Institute of Science (IISc), Bangalore told this Correspondent.

“It also implies that the remaining wild populations may also maintain such genetic diversity,” she said.

South Asia’s vulture population fell precipitously mainly due to an anti-inflammatory drug called diclofenac once routinely administered on cattle. Vultures that scavenged on cattle carcasses that contained traces of the drug often died from toxicity and kidney failure.

The Oriental White-backed vulture, once considered the most common large bird of prey in the world, declined by 99 per cent between 1990 and 2007. The populations of Long-billed and Slender-billed vultures similarly declined to just 2.5 and 2.3 per cent of their population during the same period.

Currently, an estimated 10,000 Oriental white-backed, 30,000 Long-billed, 1,000 Slender-billed vultures exist in the country.

“'Recent success with breeding of all three species in captivity, decrease in diclofenac incidence in ungulate carcasses and significant slowing of vulture declines in the wild suggest that large-scale re-introductions of Gyps vultures may very soon be possible,” says the paper.

Vultures will perhaps never return to their original populations, but even if they reach 30-40 per cent of their former abundance in, say, three decades, then they will return to their all important ecological role as keystone scavengers, Dr Ishtiaq said.