Vulture carcass disposal
Vultures are extremely effective and efficient scavengers, with a flock of birds being able to reduce an adult cow carcass to bare bones within an hour. This rapid cleaning mechanism has been the traditional way of disposing of carcasses in Asia, and placing carcasses of animals on the outskirts of villages or at large municipal dumps was and still is common practice.
The collapse in vulture numbers in the Indian subcontinent means that there is now an abundance of available meat and carcasses across the region, and other scavengers are now filling the gap left by vultures.
The mass of meat that used to be disposed of by vultures was astronomical. While vultures may only feed every 2-4 days, they need to consume the equivalent of around a 1/3 of a kilogram of meat per day in order to fulfil their energetic requirements. Over a year, a single bird will consume around 120 kg.
During the early 1990s, there were an estimated 100 to 160 million vultures in India that consumed around 20 million tonnes of carrion.
With the almost complete collapse in vulture numbers, South Asia has now lost 99% of its carcass disposal system. Vulture declines have been associated with an increase in feral dogs across the region, with government statistics in India showing that feral dog populations that numbered 17-18 million in the early 1980s were close to 30 million in 2005. These increases have occurred despite intensive control measures in India. At carcass dumps the situation is even more severe, with packs of several hundred dogs taking the place of the hundreds or thousands of vultures that used to be present. Such large packs of dogs are very aggressive and the Indian press has reported several cases of children and adults being killed.
The increase in dog numbers and rotting animal carcasses has major implications for the potential risk of both human and animal diseases, including anthrax, brucellosis and tuberculosis. Of major concern is the likelihood that the increasing dog population is furthering the spread of rabies in the region. India has the highest incidence of rabies in the world (about 60% of all documented cases)
and of the 20,000 cases each year, 96% of these are a result of dog bites.
An economic evaluation of the costs associated with the decline of vultures and management and cost of rabies in India estimates that over the period 1993-2006 the health costs would be in the regions of US$ 34 billion. The costs of conserving vultures are a fraction of this total.
Towers of Silence
The Parsi religion prohibits the burial or cremation of their dead. Instead, they hold a 'sky burial' where the body is left in the open to allow nature to take its course. In India, vultures were responsible for cleaning the bodies left at the ceremonial centres such as the Towers of Silence in Mumbai, usually within a matter of hours. Since the decline in vulture numbers, the Parsi are having considerable difficulty in taking care of their dead.
Similar sky burials are practiced by the Buddhist communities on the Tibetan plateau, although it is not known if this practice has been affected by a decline in vultures.