IT was a clear and pleasant October evening. The forest was silent except for occasional birdcalls. A Giant Malabar Squirrel scampered along a low branch. The deciduous forest patch was at its best after the monsoon showers, the grass a verdant green. We were in the middle of a small valley, the five of us, anxiously scanning the tall trees around for signs of activity.
We were at the abode of the vulture, or the valley of the vulture, as it is popularly known. The Chitalayam forests inside the Wayanad Wildlife Sanctuary in Kerala are a fine patch with abundant wildlife, greenery and water holes. Suddenly there was activity on a tall tree. We had, a little earlier, identified eight nests in the locality. The nest on this particular tree looked new and considerably larger when compared with the rest. A large vulture flew out of the nest; magnificent bird! For some of us it was for the first time that we were looking at a wild oriental white backed vulture. More visual treats were in store. One after the other, two more birds left the nest. One landed on the branch of a nearby tree, but the third one gained height.
The white backed vulture (Gyps bengalensis) is a medium sized vulture, once common in the sub-continent. Its wings are black, the neck ruff, and rump and under wings white (www.arkive.org/species/GES/birds/Gyps_bengalensis/-reference_2) The bare head and neck are black and the bill is silver. It is 75 to 85 cm long, and has an imposing look and majestic movements.
These birds are found in colonies and are sociable creatures. At a time there may be several nests on a tree. Nests are made up of sticks, leaves, branches, etc. The breeding season is from January to November. The female lays one egg at a time and the incubation period is 60 days. The chicks are taken care of by both parents for nearly three months.
Vultures are scavengers/carcass eaters. "I have seen a colony finishing off a dead elephant in less than three hours. They devour carcasses with amazing speed," says P.N. Sasidharan, Deputy Range Officer, Wayanad Wildlife Sanctuary. All over the sub-continent, vultures are found near human habitation and used to feed on dead animals laid out in the open after skinning the hide. They are an integral part of urban and village landscape. Their absence will have catastrophic impact on the health of the environment. When vultures are no longer around, carcasses will decay and lead to the outbreak of TB, anthrax and foot-and-mouth disease. Vultures will be replaced by less favoured scavengers like rats and dogs. Diseases spread by them have become rampant in urban India too.
In the 1990s the numbers of the white backed vulture began to drop dramatically. Today it is one of the most critically endangered bird species. Parts of the country, particularly urban and semi-urban areas where the vultures were once common, have seen a near total loss of the species. Even wild populations have dwindled and nestings are few and rare.
"In Kerala, the vulture has long been absent, except for very rare wild populations and this nesting in Chitalayam is indeed very important," says Dr. Sasikumar, ornithologist, who is doing field research in the area. There are several reasons for the disappearance of the vulture from Kerala. Change in life style and increased awareness of public hygiene are prime. "I don't remember seeing vultures in Kerala at all. But it is true that their populations have dramatically dwindled in the sub-continent, but before jumping to conclusions we need to find out why," says Dr. Lalitha Vijayan, ornithologist and Principal Scientist at the Salim Ali Center for Ornithology and Natural History (SACON), Coimbatore, Tamil Nadu. "Wild populations like those in the Chitalayam forests are of immense value because they are perhaps one of the few colonies that are still alive," adds Dr. Sasikumar.
Diclofenac poisoning
A study by Dr. Rhys Green of the Royal Society for the Protection of Birds and the University of Cambridge, indicates that the rapid decline in the population of the white backed vulture, the long-billed vulture (Gyps indicus) and the slender billed-vulture (Gyps tenuirostris) in India, Pakistan and Nepal, may have been caused by diclofenac poisoning. Diclofenac is an anti- inflammatory drug used widely. In South Asia, its veterinary use was particularly widespread in the last decade. It became popular as a veterinary drug in India in the early 1990s. Early theories of a viral or bacterial disease, or the impact of some toxins causing the mass deaths of vultures were laid to rest when the results of a field study from Pakistan were published by the Nature Magazine in January 2004. (It was carried out jointly by the Ornithological Society of Pakistan and the Peregrine Fund.) Of 259 dead birds examined, scientists found out that 85 per cent of the deaths was caused by visceral gout, a medical condition induced by renal failure. Heavy metal poisoning or pesticide poisoning was not found. All the vultures dead by visceral gout were tested positive for diclofenac.
A study by Lindsay Oaks of the Peregrine Fund showed that tissues of livestock treated with the standard veterinary dose of diclofenac shortly before death were lethal to captive vultures and that a high proportion of wild vultures found dead in Pakistan were contaminated with diclofenac and had the same symptoms as the poisoned captive birds in the scientific experiments. The birds succumb to kidney failure and visceral gout. Early symptoms of affected birds are the way they hang their heads down to their feet for long periods. Even at 10 per cent of the recommended dose for mammals, diclofenac is lethal to vultures, recent studies have shown.
Dr. Muraleedharan, head of the Toxicology division at SACON, says that the possibility of other causes such as poisoning by mercury or arsenic or viral infections has to be investigated again. "The population decline of vultures in India started much before the use of diclofenac became popular among vets. We need further investigations," he adds.
"A survey conducted by the Bombay Natural History Society (BNHS) shows that the population of the white backed vulture has come down by more than 95 per cent since 1990. It is an alarming trend and the three species of the vultures have been put in the critically endangered list," observes Dr. Sasikumar.
"The wild populations are found in these areas from time immemorial. Tribals call this area Kazhukankolly or the home of the vulture. They mostly feed on carcasses of wild animals, which are free of any diclofenac poisoning. Couldn't it be the reason for their survival? We need to have a special protected area status for these forests in Wayanad, with a focus on vulture protection" hopes Mr. Dhanesh Kumar, Assistant Wildlife Warden at Wayanad.
Meanwhile ornithologists and environmentalists are examining captive breeding. Reports from Pakistan say that the provincial government in Punjab has decided to set up a captive breeding centre for vultures. The vulture population in the region has gone down by 95 per cent. A vulture care centre has been started in Chandigarh also. As recent as in the 1980s, white backed vultures were considered the most abundant avian scavengers in the world. In 10 to 15 years, they have found their place in the Red Data book. The Peregrine Fund has warned that "their loss has important economic, cultural, and human health consequences".
Dramatic decline
The decline of the vulture population is one of the most dramatic cases of decline of any wild species. And the link between this decline and a popular drug used for treating humans and animals has been suggested by leading research organisations in the world. Has any one looked at the impact of diclofenac on humans and other animals? Also there needs to be further study of the possibility of exposure to lethal chemicals, the impact of climate change on the mortality rates of these birds. The question whether the vulture population in India is getting exposed to damaging quantities of diclofenac has also to be answered.
As we trekked back from Kazhukankolly, a distressing thought crept into our minds.
Were we watching one of the last remaining vultures in our country? The good news is that more nestings have been reported from other parts of Wayand. My friend and environmentalist M. Gangadharan called in the last week of January 2005 to say that more vulture nests had been found in Pulpally and Tholpetty. "Are you not coming to see them?" he asked enthusiastically. Good news indeed.
sridevimohan@hotmail.com
