Disappearing vultures

While the decline in the population of tigers has been in sharp focus in recent years, an even faster drop in the number of vultures has gone largely unnoticed. Their population is reckoned to have plummeted by a whopping 95 per cent in the past 15 years, pushing them to the verge of extinction. Even a bird sanctuary like the Keoladeo National Park, which had about 700 vultures in the early 1990s, has no vulture now. What is of even greater concern, this phenomenon is not confined to India alone, though the incidence of vulture deaths is perhaps the largest here. The drop in the vulture count has been noticed also in the neighbouring countries, especially Pakistan, Bangladesh, and Nepal. Equally disconcerting is the fact that all the three species of the Asian vulture (slender-billed, long-billed, and white-billed) are on the endangered list, portending the total elimination of this useful bird from the sub-continent. Should that happen, the consequences would be grave. The concern is not about the resultant imbalance in the natural fauna alone. More than that, vultures are nature's scavengers and play a useful role in the management of bio-waste, notably animal carcasses. Without them, these remains will be left to decompose, causing environmental problems and health hazards for animals, including livestock, as well as human beings. What is worse, if the space vacated by the vultures is filled by other birds and animals, such as crows and dogs, the menace will aggravate manifold. Rather than tackling these wastes in situ, they would tend to spread them around, with the obvious hazards.

Significantly, the high levels of toxic residues in dead animals (due chiefly to the indiscriminate use of pesticides) have, for long, been deemed as the main cause for the unnatural death of vultures. But it has now been conclusively proved that pesticides alone are not responsible. The bigger culprit is an anti-inflammatory drug called Diclofenac, which veterinarians tend to use liberally for treating domestic animals. This was first confirmed in Pakistan in 2004, when over 85 per cent of nearly 360 vulture deaths were found to have been caused by the presence of the residues of this drug in the animal corpses consumed by the victims. Subsequently, studies in India bore out the same finding. Birds feeding on the carcass of an animal that had died shortly after treatment with Diclofenac suffered kidney damage and other complications, leading to their demise.

Prima facie, banning this drug would appear to be an easy solution. But there are practical difficulties in doing so unless a suitable alternative is discovered for this otherwise useful medicine. Of course, a few other drugs, especially Meloxican and Ketoprofen, have been reported in the literature to be a possible replacement of Diclofenac, but more tests and trials are needed to ascertain that. Till an effective alternative is discovered, management strategies would have to be adopted to not only curb the death of vultures but also to augment their population through artificial breeding. Though a beginning in this direction has already been made at the captive vulture breeding zone in Pinjore, near Chandigarh, this effort needs to be scaled up substantially, considering the extent of population depletion. Besides, veterinarians too need to be careful and avoid using excessive doses of potentially injurious drugs.