In the last decade, vultures have nearly vanished from India and it is due to this reason they are listed by World Conservation Union as critically endangered, said Kirti Dua, incharge, wildlife centre of Guru Angad Dev Veterinary and Animal Sciences University (GADVASU) and professor of veterinary medicine, in a meeting held on the campus on Friday.
The initial hypotheses for the drastic decline in population were non-availability of food-dead livestock- as they were perhaps being removed for commercial purposes, or an unknown viral epidemic disease. But subsequently it was detected diclofenac, a frequently used painkiller in the domestic animals, as the main and probably the only cause of the crash in vulture numbers across South Asia.
Experiments showed that captive vultures are highly susceptible to diclofenac, and are killed by kidney failure within a short time of feeding on the carcass of an animal treated with the normal veterinary dose. This does not mean that other causes of mortality should be ignored.
Chicken, New World vultures, that are more closely related to storks, and crows can tolerate very high doses of diclofenac without mortality. Some scavenging birds in Asia, including the commonly seen black kite, have so far shown no signs of decline.
Removal of a major scavenger from the ecosystem will affect the equilibrium between populations of other scavenging species and/or result in increase in putrefying carcasses.
In some areas the population of feral dogs, being the main scavenging species in the absence of vultures, has been observed to have increased resulting in disease risks for wildlife, livestock and humans like rabies and anthrax, said the GADVASU expert.
Therefore it is essential to protect vultures in an environment where they will not be exposed to the drug. In order to ensure vulture survival it is necessary to bring them into captivity for breeding purposes.