Hooded vulture numbers take a nose-dive
Saturday September 03 2011
Most vulture species keep their distance from humans, preferring open savanna plains or sparsely populated settlements.
The exception to the rule is the hooded vulture, which until recently was seen in villages and towns, wandering around huts and feeding on carcasses from abattoirs as well as slaughterhouses.
“The hooded vulture is a very successful human commensal, whose decline is worrying,” explains Dr Darcy Ogada, the assistant director of Africa programmes at The Peregrine Fund.
Commensalism is a relationship between two organisms where one benefits while the other is neutral — it neither harms nor benefits. For example, the relationship between cattle egrets and livestock. As the cows graze in the fields, they stir up insects which the egrets eat.
Dr Ogada says the ability of hooded vultures to adapt to humans puts them at high risk of eating poisoned food in rubbish pits or being captured for food or witchcraft.
“It’s a wake-up call to shelter the remaining members of the species. Rapidly changing environments such as where the only tree species they nest in has been cut down or their preferred food has disappeared puts highly specialised species at great risk of extinction,” says Ogada. “But in this case you have a non-specialist like the hooded vulture vanishing.”
Dr Ogada says estimates from a 1999 survey put the entire African population of the hooded vultures at between 200,000 and 330,000 birds. “Today, we estimate that the population does not exceed 197,000 birds. However, it’s likely to be lower based on the demand for this bird for food in West Africa,” he says.
In Kenya’s Maasai Mara, based on the work of Dr Munir Virani (also of the Peregrine Fund and among the leading raptor scientists in Africa) and his colleagues, there has been a 62 per cent decline in the past 30 years.
Dr Ogada adds that the hooded vulture is unique in that it has separate urban and savanna populations throughout most of its African range.
“Urban populations used to be widespread near slaughter houses and rubbish dumps especially in the Western Province towns of Kakamega, Eldoret and Kisii. Today, a few can still be seen around Kakamega,” he says. “The savannah populations have decreased and are uncommon in the Mara, Laikipia and Tsavo regions. There are still some populations in the lower Tana Delta and near Wajir where they used to be quite numerous.”
The precise reasons for the decline of this vulture are not known, but scientists speculate that poisoning through the consumption of laced carcasses often meant to kill large carnivores and capture for food and witchcraft in West Africa may be among key reasons.
Reviled and revered
Vultures are equally reviled and revered in many cultures. In ancient Egypt, kings and queens wore gold tiaras with a cobra and vulture on them, symbolising fertility among other good things.
The hooded vulture also plays a vital part in protecting people and their domestic animals from diseases such as anthrax and other harmful pathogens because they eat carrion and other organic refuse, mainly from butcheries or slaughterhouses.
In South Asia, vultures have an important social significance. Among the Parsi community in India, fire, water, air and earth are pure elements that need to be preserved. Hence the dead are laid in “Towers of Silence” — circular pillars built on hilltops or low mountains where the corpses are disposed of by scavengers.
This ancient custom, also known as sky burial and similarly practised by Tibetan Buddhists, ended abruptly in the past decade due to the collapse of vulture populations in the region. At more than 96 per cent in the past two decades, the decline in Asia has been drastic. Experts attribute this largely to the use of diclofenac to cure livestock ailments and which in turn causes high levels of renal failure in many species of vultures. Regional governments banned it in 2006.
In Africa, uncontrolled use of agro-pesticides like the highly toxic carbofurans sold under the name “Furadan” have contributed to the decline. Although banned for use in the US where it is manufactured, Furadan is still sold throughout Africa and consumers only need to ask for “lion killer” in their agro-vet shop to purchase it.
In Kenya, its sale was suspended in 2008 by the US manufacturers in response to a public backlash due to a spate of wildlife poisoning incidents in the Maasai Mara. However, the product was never fully retracted and it is still being used to poison wildlife. In rural areas, it is used to lace livestock carcasses to bait predators in retaliation for preying on livestock. A minute amount can kill a full-grown lion in minutes.
“In India, estimates of the health costs of the loss of vultures and subsequent increases in dogs and as a result increases in rabies infections in humans are about $1.5 billion annually,” says Dr Ogada.
In Africa, studies have yet to put a definitive cost but researchers believe it will run parallel to the Indian sub continent as both harboured vast populations of the vultures until the past two decades.