The Great Indian Vulture Decline
Once a vulture paradise, India has become a tomb for these magnificent birds, with a dramatic decline in their population. Some scientists have advocated a ‘disease hypothesis’ and estimated that the decline of the White-backed and Long-billed Vultures is up to 90 per cent in the subcontinent. But this estimate has been made without thoroughly surveying past or present vulture strongholds. Fears were also expressed that Bharatpur’s vultures had been wiped out, even though these birds forage in large areas of about 10,000 sq. km. or more, which can include Agra and Delhi. Moreover, vulture sightings have been reported from all over India in the last two years.
The disease hypothesis states that the Birna or Adeno virus, one of the symptoms of which is a drooping head, killed India’s vultures. A year ago, the same group had said that vulture mortality was due to pesticide bioaccumulation. The disease hypothesis has not yet been proved and is not supported by several vulture experts and ornithologists from India and abroad.
Human persecution, not disease
A drooping head is the normal resting posture of the Griffon’s and White-backed Vultures, and need not indicate disease. Dr. Jose Tella of Spain who observed dead vultures around a poisoned carcass in Rajasthan in 1994, noticed the head-drooping behaviour in one of them. He and Dr. Ohad Hatzofe from Israel opined that poisoning had played a major role in the Indian vulture decline. Dr. Warren Goodwin of Zimbabwe also mentions head-drooping in vultures as a classic indication of poisoning.
No sick or dying vulture has yet been investigated for disease. The presence of some disease germs in dead vultures may be normal as they feed on diseased carcasses and corpses. Hence these germs may be dormant in them. Observing pathogens in the carcasses of healthy vultures may mean that they can withstand some pathogens, rather than succumb to them.
From 1996 to 1999, over 200 vultures died in Bharatpur according to BNHS scientists, who claim to have observed birds dying after being afflicted by the head-drooping syndrome for 30 to 32 days. Without marking or banding, it is difficult to say which bird died and after how long. These carcasses were not investigated for poisons.
Vultures have always been harassed, trapped and killed out of ignorance, dislike or fear. In some places, vulture eggs and adults are even fed on. Vulture populations in and around airfields are a threat to aviation and reportedly caused a loss of Rs. 300 crores annually from 1980 to 1994. Though the BNHS recommended ecological solutions, by and large this led to efforts to exterminate selected vulture populations, which led to many of the birds seeking refuge in and around Protected Areas, forests and villages. In their new homes, vultures succumbed to rampant poisoning of wild and domestic animals by poachers and villagers. The large number of tigers, leopards, and other carnivores poisoned between 1989 and 1999 is an indicator of the high mortality rates that vultures too have probably suffered.
There is a significant relation between the poisoning of wild animals and nationwide vulture mortality from 1989 to 1999. In 1993, Kannan mentioned villagers laying poison-baited carcasses to kill marauding carnivores in the Anamalais, thereby wiping out all vultures in the area. A report in Down To Earth (May 15, 1999), mentioned the instant death of vultures after consuming a poisoned cow carcass in Kutchh. Cattle-lifters usually poison livestock to steal the hide and bones. There were reports of cows having died after feeding on zinc phosphide, a rodenticide used by hide collectors in Bharatpur. The indirect but equally lethal effect of pesticides on birds and animals cannot be ignored and may have played a role in the vulture decline as well.
In the early 1980s, Dr. Agarwal and Dr. Bhatnagar of the Indian Agricultural Research Institute had experimented on the toxic baiting of vultures and Pariah Kites, in order to eliminate these birds from sensitive areas like airports and defence installations. The birds died within one to three hours of consuming meat laced with methyl parathion.
Strategy for the future
My hypothesis is that human persecution, not disease, is responsible for the fall in vulture populations. Setting up feeding stations to provide poison-free food, clean water, bone chips and perches within open-roofed wire-mesh enclosures could be the best in situ conservation tool to save these birds. Protecting natural habitats and educating communities would be sensible long-term options. One way or another, it is time that governments, institutions, scientists and communities came together to save the vultures.
Author: Dr. S.M. Satheesan, First appeared in: Sanctuary Asia, VOL. XXI. NO. 3. June 2001.