On a wing and a prayer

[Mahazareen Dastur]

When Kevin Carter, a South African photojournalist, photographed a vulture stalking a dying child in Sudan in 1993, many expressed outrage. After all, vultures are looked upon as reviled, foul things, and Carter himself was reviled for having done nothing to help the child. Notwithstanding the outrage, the photographer went on to win a Pulitzer Prize for the picture in 1994. It bears saying that the combination of vulture and a child near death generated very strong and understandable reactions.

Traditionally, vultures have been looked upon as repellent creatures. However, their services to the ecosystem are only now being appreciated—and missed. With vulture populations in most places around the world declining precariously, it is ironical that this bird has engendered the interests of scientists and laymen alike, only now, when most species of the bird are listed as critically endangered by the International Union for Conservation of Nature (IUCN).

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 (Cathartes aura), Black Vulture (Coragyps atratus), and King Vulture (Sarcoramphus papa). The Old World vultures belong to the family Accipitridae are found in Africa, Asia, and Europe. All vultures are carrion eaters except for the Palm Nut Vulture (Gyphohierax angolensis) 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 (for example, the lethal Bacillus anthracis that causes anthrax) that are pathogenic to many other animals. Their digestive acid is strong enough to enable this. They are credited with reducing the occurrence of disease as they can eat diseased animals and prevent disease-causative organisms from spreading. 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 bald head (devoid of feathers) so as to keep the head clean when feeding. New World Vultures are known to urinate straight down their legs; the uric acid kills bacteria accumulated from walking through 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 large distances (500–1,000 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 per year.

There are nine vulture species found in India: Oriental White-backed Vulture (Gyps bengalensis), Long-billed Vulture (G. indicus), Slender-billed Vulture (G. tenuirostris), Egyptian Vulture, Indian Griffon Vulture, Himalayan Griffon, Cinereous Vulture, Red-headed Vulture and Bearded Vulture. The first three were the most common. Unfortunately, their populations have declined precariously since the 1990s—a whopping 97% of these three species has been lost. In India, Nepal and Pakistan, veterinary use of the non-steroidal anti-inflammatory drug diclofenac has been cited as the main, and perhaps the only, cause of the population declines. It has been prescribed by veterinarians as a painkiller and for fever relief among domesticated cattle. Vultures are exposed to diclofenac when they feed from carcasses of livestock that die within a few days of treatment and contain residues of the drug. Given that up to 200 vultures have been sighted as feeding on a medium-sized carcass, one such poisoned carcass can kill a huge number of vultures. Their near-disappearance has tilted the equilibrium in favor 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 has been estimated that less than 0.8% of domesticated animal carcasses available to foraging vultures would need to contain a lethal dose of diclofenac to have caused the observed population declines.

Above: The Red-headed Vulture in Corbett National Park, India 

(Source: Wikimedia Commons)

Curiously, their physical form and function have led to vultures having a place of pride in the cultural arena too. The ancient Egyptians 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 their dead, have relied on a combination of sunlight and vultures for the task.

Once the causative agent was identified, the government devised a Recovery Plan: (a) identifying a safe alternative drug, (b) purging diclofenac from the environment, and (c) establishing a full-scale conservation breeding programme for future reintroduction once diclofenac had been 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 more cheaply. A recent three-day vulture estimation exercise at the Panna Tiger Reserve (Madhya Pradesh) threw up some encouraging results, with some 1,700 vultures being counted within its periphery (however, newspaper reports do not provide an absolute percentage increase over the last-known count). Captive breeding centers in India run by the Bombay Natural History Society, with support from the Royal Society for the Protection of Birds (UK), have been able to rear 18 birds in 2011, almost double the number last year. Other vulture conservation programs in Assam and Gujarat have been reporting 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 some chinks in the armor. Diclofenac manufactured for human use is still being used illegally 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.

Above: Map of vulture distribution in and around India before their dramatic decline

(Source: Wikimedia Commons)

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 their 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 sufficiently attractive to deter birds from utilizing carcasses encountered elsewhere. Therefore, restaurants can reduce, but not eliminate, vulture mortality through diclofenac exposure. Some studies have also emphasized the importance of the diversity of prey in the vultures’ diet and its relationship 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, by 2011, breeding programs helped increase its numbers to 400, including 200 birds thriving in the wild. Clearly, there is hope.

A shortened version of this article first appeared in the March 15, 2013 version of Down to Earth magazine (http://www.downtoearth.org.in/content/wing-and-prayer).