By Dr. Becker
One of My Favorite Birds is Facing Extinction in Asia
Just 15 years ago there were millions of vultures on the Indian subcontinent.
Today, they are in danger of completely disappearing from the earth.
Two species of vulture native to India, Pakistan and Nepal have declined by 97 percent, and another species by 99.9 percent.
The three species are the oriental white-backed vulture, the slender-billed vulture, and the long-billed vulture.
The race to extinction of these remarkable birds has happened faster than even that of dodo birds.
No other wild bird has seen its population decimated with such swiftness.
The name vulture actually describes two different groups of scavenging birds – the New World vultures found in North and South America, and the Old World vultures found in Africa, Europe and Asia.
Vultures are on every continent except Australia and Antarctica.
The Killing Agent: Diclofenac
At the heart of the decline of south Asia’s vultures is a veterinary drug called diclofenac.
Diclofenac is a non-steroidal anti-inflammatory drug (NSAID). It entered the veterinary market on the Indian subcontinent in the early 1990s and is used as an inexpensive treatment for inflammation, pain, fever and lameness in livestock. Losing livestock to lameness or illness can be devastating to Asia’s small farmers.
When the drug is administered to cattle shortly before death, it remains in the tissues of the carcasses, which is how vultures are exposed to it.
On the Indian subcontinent, dead livestock are typically left out for scavengers to take care of, with vultures the first in line. Dead animals are not widely eaten in Pakistan for religious reasons, or by the many vegetarians in India.
In addition, in those countries fuel is scarce and can’t be spared to incinerate carcasses.
A 2004 Peregrine Fund study showed that both captive and wild vultures contaminated with diclofenac shared the same symptoms of visceral gout and kidney failure, causing death. Visceral gout is a condition in which white uric acid or urate crystal deposits develop in the soft tissues of various organs.
Other studies have shown that at just 10 percent of the recommended dose for animals, diclofenac is lethal to vultures.
Once the link was established between the drug and millions of dead vultures in south Asia, diclofenac was banned for veterinary use. Sadly, it is still being sold and used illegally.
While livestock carcasses are not usually left out in the open in the U.S., we should all be aware of the situation in south Asia. FDA-approved veterinary use of diclofenac in the U.S. has so far been limited to a topical solution for horses to relieve lameness.
Though remote, the possibility of poisoning scavenging birds exists. It can be avoided by not leaving carcasses of dead animals in fields, shallow graves or uncovered landfills. As long as safe disposal practices are followed, drugs should not cause undue problems for scavenging wildlife.
As a result of the vulture die off, feral dog populations on the Indian subcontinent have exploded. Both the dogs and decomposing animal carcasses dotting the countryside can spread disease.
Local tradesmen who rely on clean hides and bones to make their living are finding their lives much harder without the vultures. Many cattle owners who can ill afford it now must pay for carcass burial or cremation services.
The Parsi people in Mumbai dispose of their dead in what are called sky burials. The corpses are placed on outdoor “towers of silence” to be picked clean by vultures. They have been forced to turn to alternatives that cannot include cremation, which is forbidden.
Vulture Conservation Efforts
A number of organizations are involved in projects designed to improve the plight of south Asia’s nearly extinct vulture population.
Captive breeding programs for several species of Indian vulture are underway. Vultures are long-lived and slow breeders, reaching breeding age at about 5 years old. Obviously, breeding programs will take decades. The goal is to eventually release captive-bred birds into the wild once the environment is free of diclofenac.
In 2009, a slender billed vulture was successfully bred in captivity for the first time. The year before, oriental white-backed vultures were bred for the first time, with additional chicks arriving in 2009.
The more vultures the breeding centers can bring into captivity, the better the chance of survival for the species. Other measures must include banning the retail sale of diclofenac.
Another conservation effort is the establishment of vulture safe havens -- also called safe zones and ‘vulture restaurants’ -- in the wild. These are locations where there is very little risk of diclofenac poisoning in the areas surrounding the remaining wild vulture breeding colonies.
These sites will retain vultures within their natural habitat rather than in captivity, and the hope is also to use them as future release sites for captive bred birds. Release of captive reared birds must be limited to areas where it has been established vultures can be protected. These sites must also be congregation areas for wild vultures.
The Value of Vultures
I think many people either ignore vultures or consider them another loathsome species. The job nature has assigned to them is unappealing. And the manner in which these fabulous birds of prey are portrayed in movies, TV shows and other media is less than flattering.
Vultures are of tremendous value to the ecosystem as scavengers, especially in hot climates. They are able to eat up to 2 pounds of carrion in a single meal, which is over 10 percent of their body weight.
The stomach acid of vultures is extremely corrosive, which allows them to safely clean up the carcasses of animals infected with deadly bacteria like botulism, classical swine fever and anthrax.
And thanks to another brilliant design of nature, New World vultures urinate straight down their legs, and their urine kills bacteria they’ve picked up from walking through dead carcasses.
I realize the physiology and lifestyle of vultures isn’t good dinner table conversation, but I do hope everyone reading here today understands how vital these magnificent scavenging birds are to our natural world.
“Vultures are the ultimate recyclers – able to strip a carcass in just a few hours, they keep our environment clean and disease free.”i