September 17, 2013
When I read a headline in Scientific American that said vultures were facing extinction, I was incredulous. After all, they aren’t picky about what they eat – they eat road kill! And I was right about the North American vultures, the black vulture and the turkey vulture. As a matter of fact, their numbers are growing, as are interactions between suburbanites and these useful birds with unattractive habits.
It is a different story with their Old World cousins, however. In West Africa, populations of almost all vulture species have declined by 95 percent in the last 30 years. There are a number of reasons given for this die-off. Power lines and wind farms take a toll. Poachers kill them to hide poaching sites, and they are collateral damage when farmers poison carcasses to kill hyenas and lions. They are sold as meat or medicine, and they suffer when herd migration patterns change.
On the Indian subcontinent, where, until recently, there were millions of vultures, the numbers of three species of Asian vultures have dropped by 97 to 99 percent in just the last ten years. This is faster than the decline of the dodo.
There are several things that might be contributing to this decline, including malaria, pesticide residues, and cattle being butchered instead of left for scavengers. However, the overwhelming problem in India is the use of a veterinary drug called diclofenac. It is a NSAID used since the early 1990’s as a cheap treatment for inflammation, pain, fever and lameness.
If vultures eat carcasses containing diclofenac, they suffer from visceral gout and kidney failure, causing death. Because vultures are social when they eat, huge wakes of them gather around the same carcass, killing between 50 and 500 birds at a time. (‘Wake’ is the collective noun for feeding vultures.)
When it was determined that diclofenac was the culprit, it was banned for veterinary use in India, Pakistan and Nepal in 2006. However, it is still available in large vials for “human use.” It remains popular because it is cheaper and works more quickly than other drugs that serve the same purpose.
The lack of vultures is creating huge problems for India and its neighbors. Dead livestock are usually left out for scavengers rather than incinerated due to the scarcity of fuel and religious prohibitions. The accumulation of these animals in carcass dumps foster diseases including botulism, swine fever, and anthrax. Feral dogs feed on the carcasses, and their population is exploding. India already has the most cases of rabies in the world, and this just makes it worse. The dogs attack wildlife and have even been known to attack and kill children. They can also carry distemper which threatens the dhole, an indigenous wild dog, as well as tigers and Asiatic lions.
Another problem is that it threatens the livelihood of local hide and bone collectors who depend on the vultures to clean the carcasses they collect.
Another group affected by the lack of vultures are Zoroastrians and a few others around Mumbai who practice ‘sky burial.’ Human remains are left out in the open in what are called ‘Towers of Silence,’ to be picked clean by vultures. They use this method to avoid contaminating the sacred elements of earth, water, and fire.
Conservation efforts are now under way, but it will be a difficult process to bring these birds back from the edge. They do not reach maturity for five years after they fledge and then breed slowly. Captive breeding programs are in place and have had some success. Safe havens for vultures, called ‘vulture restaurants,’ have also been created.
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