Silent Towers, Empty Skies

Article excerpt

On the round-the-world trip chronicled in his book Following the Equator, Mark Twain stopped off in Bombay (now known as Mumbai) and, as part of the standard tourist circuit, was taken to the Towers of Silence, where the Parsi community brought their dead. "On lofty ground, in the midst of a paradise of tropical foliage and flowers, remote from the world and its turmoil and noise, they stood," Twain wrote. "The vultures were there. They stood close together in a great circle all around the rim of a massive low tower--waiting; stood as motionless as sculptured ornaments, and indeed almost deceived one into the belief that that was what they were."

The assemblages Twain saw are a thing of the past. The vultures have vanished from Mumbai, and populations of three vulture species have nosedived all over the Indian subcontinent: India, Pakistan, Bangladesh, Nepal. The die-off has had profound consequences for public health, as well as for Parsi funerary practices. Biologists at first suspected an infectious agent and feared migrating vultures might spread it to the savannas of Africa. But research in Pakistan by The Peregrine Fund points to an unsuspected cause: an anti-inflammatory drug called diclofenac sodium, widely used in veterinary as well as human medicine. "This is the first known case of a pharmaceutical chemical involved in damage to a wildlife population," says toxicologist Robert Risebrough, who has studied the effects of toxics on California condors and other endangered birds, and has made several visits to India to investigate the vulture die-off.

The relationship between humans and Old World vultures is an ancient one. Long before the rise of Homo sapiens, hominids likely tracked the scavenging birds to locate the kills of more adept predators. Eight thousand years ago, the inhabitants of the Neolithic city of Catal Huyuk in Anatolian Turkey appear to have exposed corpses to be stripped of flesh by vultures as part of the preparation for burial. If, as some archeologists and linguists believe, Anatolia was the homeland of the Indo-European language family, the Parsi practice may have its roots there.

India's Parsis follow a religion founded by the prophet Zoroaster around 1400-1200 BCE on the Asian steppes. His disciples were a nomadic people, speaking a tongue ancestral to modern Farsi, who moved south into present-day Iran. The state faith of successive Persian empires, Zoroastrianism was brought to India in 936 AD by refugees fleeing persecution by Arab Muslim conquerors. Holding earth, fire, and water too sacred to pollute with corpses, Zoroastrians relied on wild scavengers to dispose of their dead. A text from the time of the Parthian Empire, contemporary with Imperial Rome, directs believers to leave a body "on the highest places, so that corpse-eating beasts and birds will most readily perceive it." Simple platforms for exposure were later replaced by open-topped stone structures called dakhmas; "Towers of Silence" was the coinage of a 19th-century British journalist.

The dakhmas of Mumbai attracted the once ubiquitous white-rumped or Indian white-backed vulture (Gyps bengalensis). A mid-sized vulture with a wingspan approaching seven feet, the white-rumped inhabited the region from southeastern Iran to Vietnam and Cambodia. In India, it could be found wherever carcass dumps, slaughterhouses, or bone mills provided a food source. With the agricultural development of western desert regions under the British Raj, the white-rumped spread into Sind, Punjab, and Rajasthan. It's a gregarious bird, often nesting colonially and feeding in quarrelsome flocks.

Its close relative, the long-billed vulture (G. indicus), was also abundant through the western portion of the white-rumped's range, outnumbering it in peninsular India. A third form, the slender-billed (G. tenuirostris), once considered a subspecies of the long-billed, differs in bill structure and nesting habits; it occurred in smaller numbers from Kashmir through Bangladesh to Southeast Asia. …