When the vultures watching your civilization begin dropping dead...it is time to pause and wonder.
Tomorrow, September 5, has been designated as International Vulture Awareness Day. This was prompted primarily by the Asian vulture crisis, which has seen populations of several species—long-billed (Gyps indicus), slender-billed (G. tenuirostris), and Oriental white-backed (G. bengalensis) vultures—plummet to near-extinction.
The mystery of the birds' abrupt disappearance was solved in 2003 by researchers associated with The Peregrine Fund, who discovered that diclofenac, a widely-used NSAID (non-steroidal anti-inflammatory drug) given to livestock, caused kidney failure in vultures which fed on carcasses containing even minute amounts of the drug. India, Pakistan, and Nepal all banned diclofenac in 2006, but Gyps populations in southern Asia continue to decline. Presumably, this continued decline results from exposure to illegally-prescribed diclofenac, but inbreeding or other population-ecology effects in the wake of the initial crash may be a factor as well.
The loss of vultures in southern Asia has public-health and even religious implications. The affected species, like all vultures, play a critical role in disease prevention by removing carrion. In the absence of vultures, feral dogs have become the region's dominant scavengers; not only are dogs less efficient in a sanitation role, but the drastic increase in feral dog populations has led to an associated surge in human cases of rabies. For centuries, vultures have also played a key role in "sky burials" practiced in Tibet, India, and, at least formerly, elsewhere in Asia—including Persia (Iran), where sky burials were an integral part of Zoroastrian practice before the hegemony of Islam. In both Zoroastrian and Tibetan Buddhist traditions, sky burial is considered not just a practical means of disposing of a body, but also an act of charity toward the scavengers. (The Tibetan term for sky burial, jhator, means "giving alms to the birds".)
Vulture populations elsewhere in the world have also declined, though not always as severely as in southern Asia. Here in North America, the California condor (Gymnogyps californianus) very nearly went extinct and is still an endangered, intensively-managed species. Recent research indicates that lead poisoning from spent ammunition (fragments can be found not only in unrecovered quarry but also in gutpiles left behind by hunters) has been a major cause of mortality in condors; logic would suggest that black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) are subject to lead poisoning from the same source. (So are human hunters—which is an excellent argument for switching to non-toxic ammunition even where not required by law.) Vultures are too often vilified—especially in the West—as dirty, cowardly, opportunistic in the most negative sense of the word. (Their image in South America is mixed but generally more positive than in the rest of the Western world: the Andean condor [Vultur gryphus] is the national bird of Bolivia, Chile, Ecuador, and Colombia, and appears on the coat of arms of each of these Andean nations. Both the Andean condor and the king vulture [Sarcoramphus papa] were significant in Native religions.) Considering what they are and what they do, including what they do for us—they are among the most graceful of the soaring birds, harbingers of spring in some regions, ecological indicators, sanitation workers, even messengers to the gods and transport to the hereafter—awareness of vultures may be too low a goal. We should strive for an appreciation of vultures.