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Researchers report Yosemite owls are own distinct species

Article Date: 2010-09-24   Source: http://www.recordnet.com   Comments: 0

By Dana M. Nichols

Yosemite National Park, California, U.S.A. - Genetic researchers say a new study shows the great gray owls living in and around Yosemite National Park are a distinct species and should have their own name.

It has been about 26,700 years since the Sierra Nevada great grays have been able to interbreed with other great gray populations in what are now Oregon, Idaho and Canada, according to an article published recently in the journal Molecular Phylogenetics and Evolution by a team of researchers from the University of California, Davis, and the U.S. Forest Service.

In contrast, genetic evidence indicates that other populations of great gray owls have had at least some chances to interbreed since the last ice age ended about 11,000 years ago, according to the paper.

The owls are dramatic birds with yellow eyes, hooked beaks and 5-foot wingspans. They nest in the tops of towering snags and dine on small mammals such as voles and pocket gophers. Biologists say there are only about 150 of the birds within Yosemite National Park, and the species is listed by the state of California as endangered.

Sarah Stock, a Yosemite National Park wildlife biologist who assisted the research team, said the group spent months searching for the owls and collecting blood samples by using mice to lure the owls into spring-loaded noose traps.

She said it took only three to five minutes after each owl was caught in the trap to take a blood sample and release the bird. And she said the work was all done bare-handed, despite the owls' sharp talons, to make sure researchers did no harm to the animals.

"We do put a cover over their eyes, and that minimizes stress," Stock said.

John J. Keane of the U.S. Forest Service Pacific Southwest Research Station and Holly B. Ernest and Joshua M. Hull of the Veterinary Genetics Laboratory at UC Davis were the lead researchers. Their paper recommends that the Yosemite owls be named Strix nebulosa yosemitensis. The other great gray owls in North America would continue to be called Strix nebulosa nebulosa.

The paper urges the American Ornithological Union to approve the new name to recognize the Sierra owls' isolated evolutionary history and to "provide important context for ongoing conservation and management efforts."

The owls already are the subject of a number of protection efforts. In the Stanislaus National Forest just outside Yosemite, biologists have even constructed artificial snags to replace nesting spots lost to logging and fires.

Inside Yosemite, construction work is banned near great gray owl nests during breeding season, Stock said. And the use of amplified devices to broadcast owl calls - a technique sometimes used by birders eager to find an owl - is strictly banned in the park.

Stock said the great gray's calls are adapted to owl family life. She said the males have a call something like the low rumble of a jet airplane heard at a distance that they use to defend territory or communicate with a mate.

"They have a deep voice. It's a single note they vocalize over and over with," Stock said.

She said the females make a "whuup" call that rises in pitch to signal that the they are hungry and the male should bring food.

In addition to taking blood samples from 29 great gray owls in the Sierra Nevada, researchers also sampled eight owls from western Canada, 25 from southern Oregon, 22 from eastern Idaho, and nine from northern Oregon.

Then researchers extracted the owls' DNA from the blood and looked at 30 different chunks of the genetic code for each bird. That data was analyzed a number of ways using computers to determine how closely the various owl populations were related.

Their conclusion was that after the last ice age, the northern populations of great gray owls spread from the pockets of habitat where they'd survived the ice age and mixed with other great grays, but "excluded movement to the southern Sierra Nevada."

Disclaimer: This article has been reproduced from http://www.recordnet.com and placed here for comment. OwlPages.com is not responsible for the accuracy of any information in this article, and does not necessarily agree with the author's opinions.

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2009-01-05 - Great gray owls to get new nests with a little help from biologists by Dana M. Nichols - San Andreas, California, U.S.A.

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