As recently as the 1980s there were millions of vultures all over India, but the population suffered precipitous losses and the few remaining birds are mostly found in sanctuaries. The main cause for the rapid decline in Indian vulture populations seems to be the use of a pharmaceutical called
diclofenac,which was used to prevent colic in cattle. The drug turned out to be lethal to vultures who consumed the flesh of dead cows, which are considered sacred in that country are so are left out in the open when the die. After diclofenac was banned, its replacement drug also turned out to be fatal to vultures, and the remaining populations may not be viable for the species' continued existence.
In addition to the deadly drugs used to treat cattle, the overall decline in wild grazing animals in Asia has lead to a drop in the available number of dead animal carcasses for the birds to feed on.
Once widely disbursed and abundant through Asia, in recent decades the wild population of Red-Headed Vultures (also known as the Indian Black or Pondicherry Vulture) have experienced a rapid decline in range and population. The current wild population is estimated at less than 10,000 individuals throughout Asia, with just a few hundred in Southeast Asia and the rest mostly in India. Like other carrion eaters, vultures are vital to the ecosystem for disposing of dead animals, and their loss has a profound effect on the biosphere. In India, members of the Parsi faith also relied on the birds for the disposal of human remains, as burying or burning the bodies was seen as polluting the natural elements.
