September 5, 2008

Extinction Circles Giant Vultures

shadow has fallen over endangered giant vultures whose captive populations are
too small to save the species.

breeding colonies currently lack the genetic diversity to ensure survival for oriental white-backed vultures
(Gyps bengalensis) in the wild, where the birds are dropping dead from
feeding on drug-tainted meat.

vultures boast a seven-foot wingspan and thrived in South Asia until the
mid-1990s, when people started using an anti-inflammatory drug called
diclofenac to treat arthritis-like symptoms in livestock. Vultures that fed on
the tainted carcasses of the animals died of kidney failure within a day or two. 

know the problem, and we know the solution," said Jeff Johnson, a
biologist who conducted the research at the University of Michigan in Ann Arbor
and is now at the University of North Texas in Denton. "We just need to get
diclofenac out of the environment and more birds into protection before it is
too late." 

fate shares similarities with that of the California condors in North America,
which are dying from lead poisoning after feeding on
animals wounded or killed by hunters. 

shrinking population means less genetic diversity that can help species adapt
to changing environments and climates or disease outbreaks. The results could
spell extinction for the giant vultures, despite the small captive breeding
colonies in India and Pakistan. 

and other researchers took genetic samples from old museum specimens of the
giant vultures, and also collected recent feather and tissue samples from
Pakistan's last remaining wild breeding colony. They then used computer
simulations to determine that the number of vultures in captivity are not
enough to maintain genetic diversity if wild populations go extinct - a likely
case if people continue using diclofenac. 

loss of the giant vultures means fewer of nature's garbage
disposals to take care of uneaten livestock carcasses, which can become
breeding grounds for bacteria and attract rabid feral dogs. Such birds also
have cultural value for the ancient Parsi religion of South Asia, which places
deceased people on "Towers of Silence" for vultures to consume the
remains. The Hindu religion similarly reveres a vulture saint named

conservation organization called the Peregrine Fund is working to try and save the giant vultures, but faces political,
logistical and funding challenges in the vultures' home countries.

of my goals with this paper," Johnson said, "is to raise awareness of
the problem and to increase political will in India and Pakistan to get this
matter resolved." 

study is detailed in the August issue of the journal Biological Conservation.