In 1993, when South African photojournalist Kevin Carter clicked a vulture stalking a dying child in Sudan many expressed outrage. After all in most parts of the world, vultures are reviled. Carter was censured for having done nothing to help the dying child. In spite of the outrage, the photographer went on to win a Pulitzer Prize for the picture in 1994. It bears saying that the combination of a vulture and a child near death generated very strong reactions.
It is only of late that the services vultures render to the ecosystem are being appreciated—and missed. It is ironical that this bird has caught the interests of scientists and laymen alike when most species have been declared critically endangered by the International Union for Conservation of Nature.
Vultures are classified as New World vultures and Old World vultures. The former are distributed in North, Central and South America and belong to the family Cathartidae. Some examples include the Turkey Vulture, Black Vulture and King Vulture. The Old World vultures belong to the family Accipitridae and are found in Africa, Asia and Europe. All vultures are carrion eaters except for the Palm Nut Vulture which feeds principally on the fruit of the oil palm.
Nature has designed vultures in a manner appropriate to their function. These birds display remarkable tolerance to microorganisms that are pathogenic to most other animals—the lethal Bacillus anthracis that causes anthrax, for example. Their digestive acid is strong enough to enable this. Their feeding habits make vultures nature’s agents for reducing the spread of disease-causing organisms. Some vulture species locate their food using an acute sense of smell, while others use keen eyesight. A particular characteristic of many vultures is a head devoid of feathers; this enables the birds to keep their head clean while feeding. New World vultures are known to urinate straight down their legs; the uric acid kills bacteria accumulated in the carcasses, and also serves as a cooling mechanism.
Genders appear identical and it is impossible to visually distinguish males from females by sight alone. Vultures have been known to fly long distances (500 to 1,000 km in a day) and soar to amazing heights—there has been a case of a jet colliding with a vulture at 10,000 m. They mate for life, and most species lay only one egg in a year.
Vultures have not always been reviled. Their role in nature gave the bird a place of pride in some cultures. The ancient Egyptians, for example, considered the vulture to be a protecting and nurturing mother, and so their word for mother was also the word for a vulture, mwt. For many centuries, the Zoroastrians of India, whose religion does not permit the burning or burial of the dead, have relied on a combination of sunlight and vultures for the task.
There are nine vulture species found in India: Oriental White-backed Vulture, Long-billed Vulture, Slender-billed Vulture, Egyptian Vulture, Indian Griffon Vulture, Himalayan Griffon, Cinereous Vulture, Red-headed Vulture and Bearded Vulture. The first three were once common. Unfortunately, their populations have declined precariously since the 1990s—a whopping 97 per cent of these three species have been lost. In India, Nepal and Pakistan, veterinary use of the non-steroidal anti-in´¼éammatory drug diclofenac has been cited as the main, and perhaps the only, cause of the decline.
The drug was once commonly prescribed by veterinarians as a painkiller and for relief for fever to domesticated cattle. It is now well known that vultures are exposed to diclofenac when they feed on carcasses of livestock that die within a few days of treatment—and so carry residues of the drug. Given that up to 200 vultures have been sighted as feeding on a medium-sized carcass, one poisoned carcass can kill a huge number of the birds.
The near-disappearance of vultures has tilted the equilibrium in favour of other scavengers like feral dogs that can carry rabies, and has led to an increase in disease vectors due to putrefying carcasses. It is tragic then that something as apparently benign as a painkiller has led to this avian scavenger’s near-extinction. It is estimated that less than 0.8 per cent of domesticated animal carcasses available to foraging vultures would need to contain a lethal dose of diclofenac to have caused the observed population declines.
Once the causative agent was identified, the government devised a recovery plan: one, identifying a safe alternative drug; two, purging diclofenac from the environment; and three, establishing a full-scale conservation breeding programme for reintroduction of the bird once diclofenac was removed. Some gains have been made. A safe alternative called meloxicam has been identified, and is becoming more widely used now that it is out of patent and can be manufactured cheaply.
A recent three-day vulture estimation exercise at the Panna Tiger Reserve in Madhya Pradesh threw up encouraging results, with some 1,700 vultures counted in the periphery of the protected area (however, newspaper reports do not provide an absolute percentage of increase over the last-known count).
Captive breeding centres in India run by the Bombay Natural History Society, with support from the UK-based Royal Society for the Protection of Birds, have been able to rear 18 birds in 2011, almost double the number the previous year. Other vulture conservation programmes in Assam and Gujarat have reported important advances through the education of veterinarians and livestock owners to avoid treatment of terminally ill livestock, or to bury or burn carcasses of recently treated animals.
However, there are a few chinks in the armour. Diclofenac manufactured for human use is still being illegally used to treat cattle in India. Unfortunately, some of the vet medicine alternatives have not been tested for their safety to vultures and one drug in increasing use, ketoprofen, is already known to be toxic not just to these birds, but also to storks, cranes and owls. The use of supplementary feeding stations with diclofenac-free carcasses, also called “vulture restaurants”, has been considered one of the most useful management techniques for recovering vulture populations.
However, feeding stations are principally used by the non-breeding population. Vultures tend to occupy greater home ranges, cover greater distances each day and spend proportionately more time in the air during the late brooding and post-breeding seasons. Even when vulture attendance at restaurants is high, studies have shown that the predictable food source may not be sufficiently attractive to deter the birds from feeding on carcasses elsewhere. So restaurants can reduce, but not eliminate, vulture mortality through diclofenac exposure.
Some studies have emphasised the importance of the diversity of prey in the vultures’ diet to the birds’ breeding success. The jury is still out on the long-term effectiveness of these conservation activities. Consider this: almost 25 years after North America’s California Condor (a New World vulture) went extinct in the wild and dwindled to just 27 birds in captivity, in 2011, breeding programmes helped increase its numbers to 400, including 200 birds thriving in the wild. Clearly, there is hope.
Mahazareen Dastur is an environment researcher-cum-writer based in Mumbai. She blogs at mahazareendastur.blogspot.com