Snowy owls swoop southward, delighting birders

Biologists say an increase in snowy owl sightings 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.

The mostly white owls of "Harry Potter" fame are spotted in small numbers in upstate New York and other northern states every winter. This year, they've also been spotted farther south, in states where they're rarely seen.

In Tennessee, birders armed with spotting scopes and telephoto lenses scrambled from as far away as Georgia and Alabama to see the first snowy owl reported in that state in 22 years.

The owl showed up in early December in the fields surrounding a General Motors plant in Spring Hill, Tenn. Sightings were still being posted on the Tennessee Ornithological Society's Web site in late January.

Birding hot lines lit up in northern Virginia with the sighting of a young male snowy owl in early December. The bird later died after it was found, sick and weak, and brought to the Wildlife Center of Virginia in Waynesboro.

Rarely seen south of northern Ohio, snowy owls have also been reported this year in Kansas and Missouri, according to the eBird.org national bird reporting Web site.

Snowy owls nest on the ground in the Arctic tundra and many of them stay there year-round, while some winter in Canada and the northern United States. They tend to show up in greater numbers in the U.S. every three to five years, pushed by crashes in the population of lemmings, the hamster-like mainstay of their diet.

But that doesn't appear to be the reason for this year's influx.

"This year it appears the lemming population was really good," said Laura Erickson, a biologist at the Cornell Lab of Ornithology in Ithaca. "When lemmings are abundant, snowy owls have a very successful breeding season."

As a result, the owl population grows 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.

Snowy owls aren't uncommon in winter in Minnesota and Wisconsin, but they're far more plentiful than usual this year, Erickson said. At the airport in Minneapolis, biologists have had to trap and move snowy owls 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," Erickson said.

The increase in southerly sightings is most likely a temporary phenomenon. Back in the arctic next summer, the larger population of owls may devour so many lemmings that food scarcity will bring the owl population back down, Erickson said.

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On the Net:

eBird sighting database: http://eBird.org