January 28, 2009

Snowy Owls Showing Up Further South Than Usual

An increase in snowy owl populations in the South suggests that the arctic species did so well in its northern breeding grounds last year that competition is driving the young ones to warmer climates, biologists told the Associated Press on Wednesday.

Upstate New York and other northern states are considered the usual areas most snowy owls end up every winter. But researchers say this year several have been spotted farther south, in states where they're rarely seen.

The first snowy owl reports in 22 years have cropped up around Tennessee, where birders armed with spotting scopes and telephoto lenses were eager to catch a glimpse of the mostly white owls, famously seen in the Harry Potter movies.

One owl was spotted in the fields surrounding a General Motors plant in Spring Hill, Tenn. in early December. Members of the Tennessee Ornithological Society's Web site posted sightings until late January.

A young male snowy owl was reported in early December in areas around northern Virginia. The bird was later brought to the Wildlife Center of Virginia in Waynesboro where it died from sickness.

The eBird.org national bird reporting Web site said snowy owls have been reported this year in Kansas and Missouri, though they are rarely seen south of northern Ohio.

The Arctic tundra is the normal nesting ground for snowy owls, where the species nest on the ground and often stay there year-round. Some are known to migrate to Canada and the northern United States during the winter.

Every three to five years the owls tend to show up in greater numbers in the U.S. to take advantage of the increasing lemming populations, a mainstay of their diet.

But ornithologists hope to find out why this year's influx has increased.

Laura Erickson, a biologist at the Cornell Lab of Ornithology in Ithaca, said this year's lemming population was really good.

"When lemmings are abundant, snowy owls have a very successful breeding season."

However, this can result in populations growing so large that many of the young males move farther south to stake out feeding territory. An individual adult snowy owl may eat three to five lemmings per day, or up to 1,600 per year.

Erickson said snowy owls aren't uncommon in Minnesota and Wisconsin during the winter, but they're far more plentiful than usual this year.

Biologists have had to trap and move snowy owls at an airport in Minneapolis for fear they'd be sucked into a jet engine, she said. "As birds of the tundra, they're drawn to large open fields like airports."

Some scientists say the increase in southerly sightings is most likely a temporary phenomenon.

Erickson believes the larger population of owls may devour so many lemmings in the arctic next summer that food scarcity will bring the owl population back down.


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