Any fan of forensic mysteries like CSI can tell you that DNA evidence can be essential to cracking the case. A wildlife scientist at West Virginia University was part of a team that applied genetic sleuthing to another kind of unanswered question: accurately estimating species populations.

Todd Katzner, a research assistant professor in the wildlife and fisheries resources program in WVU’s Division of Forestry and Natural Resources, has been estimating seasonal population of imperial eagles in the Narzum National Nature Reserve of Kazakhstan. He and colleagues used traditional methods – counting the birds as they flew from a roost– and a less conventional approach – conducting genetic testing on feathers collected at those roosting sites.

Andrew DeWoody’s research group at Purdue University was able to extract DNA from those feathers and determine that there were hundreds of eagles that had recently visited the site.

“What you see isn’t what you get,” Katzner told British magazine New Scientist in a recent interview. “Most conservation plans are centered around nests and breeding pairs, but in reality there’s a cryptic population that you don’t see but is really important to protecting rare and endangered species.”

Traditional observation of imperial eagles in Kazakhstan tallied only 21 birds using roosts as well as 106 breeders and chicks. Genetic testing of left-behind feathers revealed a total of at least 414 birds.

Katzner said the value of using non-invasive methods like genetic testing has significant benefits.

“First, they allow us to collect data with minimal disturbance to the animal in question,” he said. “Second, in this case they resulted in substantially more information gathered with less effort than would have been collected otherwise.”

“A biologist doesn’t always see them coming and going,” said DeWoody, a professor of genetics at Purdue. “Eagles are difficult to capture, mark and resight. Biologists in the field can’t differentiate individuals, whereas by a genetic fingerprint geneticists can differentiate among individuals that have visited a site.”

“Non-invasive genetic approaches such as these are an emerging strategy to study wildlife populations,” said Katzner. “Although these techniques have been used before for mammals, our work is the first to focus on birds. Furthermore, the present study builds on earlier work to show the implications of this work for conservation planning.”

Kaztner and DeWoody’s research findings, conducted with Jamie Ivy, a population manager at the San Diego Zoo, will be published in an upcoming issue of Animal Conservation, a peer-reviewed journal published on behalf of the Zoological Society of London.

The study was funded by a National Science Foundation fellowship, the National Geographic Society, National Birds of Prey Trust and Wildlife Conservation Society.



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