New Delhi: The decline of three of Asia’s critically endangered vulture species, the best known scavenging birds, which were almost near extinction, has begun to stabilise in India and Nepal, says a paper.
The latest surveys show that the numbers of three Gyps species — oriental white-backed vulture, long-billed vulture and slender-billed vulture — have remained stable in the last couple of years and may even have reversed for the oriental white-backed.
The paper, published this month in the science journal PLoS ONE was co-authored by the Bombay Natural History Society (BNHS), a Mumbai-based NGO engaged in nature conservation, and the Britain-based charitable organisation Royal Society for the Protection of Birds (RSPB), which is funding vulture conservation projects in India and Nepal. The authors of the study include Vibhu Prakash of the BNHS and Richard Cuthbert of RSPB.
According to the study, vultures are important to humans as they dispose of the carcasses of ungulates (animals with hooves) which would otherwise be left to rot or to provide food for the growing population of feral dogs, which cause health risks and nuisance.
The report highlights the need for further efforts to eliminate steroidal anti-inflammatory drug diclofenac, which was once commonly used in treating cattle, from the vultures’ food chain.
BNHS studies attribute the decline of vulture species to the extensive use of diclofenac in treating cattle. The vultures that consumed the carcasses of animals treated with diclofenac died with symptoms of kidney failure.
The toxicity of diclofenac to vultures and the evidence of its effect on their populations were the reasons for its withdrawal, says the paper.
Prior to the ban on veterinary diclofenac in India in 2006, vulture population was decreasing at a rate of up to 40 percent a year.
According to the study, populations of oriental white-backed, long-billed and slender-billed vulture crashed throughout the Indian subcontinent in the mid-1990s.
Surveys in India, initially conducted in 1991-1993 and repeated from 2000 to 2007, revealed that the population of the white-backed vulture had fallen to 0.1 percent of its total numbers in nature by 2007 from the early 1990s.
Likewise, the population of the long-billed vulture and the slender-billed vulture combined had fallen to 3.2 percent of earlier levels.
A survey of the white-backed vulture in western Nepal indicated that the size of the population in 2009 was 25 percent of that in 2002.
The study, based on the surveys conducted last year by BNHS and Bird Conservation Nepal, was undertaken across more than 15,000 km of roads in western, central and eastern states of India and across 1,000 km of roads in the lowland regions of Nepal.
“The stabilisation of vulture numbers across India is the first sign that the government’s ban on veterinary diclofenac is having its desired impact,” said Vibhu Prakash, the lead author of the study and BNHS deputy director.
But continued efforts “are still required,” he said, “to protect the remaining small populations, including stopping the illegal use of human diclofenac in the veterinary sector”.
Populations of several species of vultures and other large scavenging birds worldwide have declined, says the study. It’s because of reductions of food availability, collisions with man-made structures, contamination with remains of spent lead ammunition and poisoning of vultures.