Showy snowy owls are back in Minnesota for one of their south-of-the-tundra forays, which happens every four or five years.
Dozens, if not hundreds, of arctic visitors are in Minnesota right now. They're in Wisconsin and the Dakotas. They're being reported in Northern states from coast to coast.
It's one of those periodic years when snowy owls, the largest of North America's owl species, move south out of the tundra. This happens every four or five years.
Ryan Brady, coordinator of the Wisconsin Bird Conservation Initiative, working in Ashland, said that December is the typical month for the arrival of snowies during an irruption year, so more of these white birds might arrive between now and the end of the month.
"In the winter of 2005-06, the last winter for a good snowy flight, we had seen seven or eight birds here by the end of November. We saw four times that many in December," he said.
Why are the owls coming south?
"The best hypothesis right now is that the owls had very successful nesting this spring," Ryan said. "We're seeing a lot of immature owls pushed south by lack of food."
Snowy owls will eat as many as five lemmings a day. In good lemming years, nesting snowies will raise as many as a dozen young birds. Nesting success often is 100 percent. When lemming populations are low, the owls don't nest at all, and they move south to find food.
Ryan thinks it's possible that lemming populations are no longer at spring levels.
"The owls would not expend the great amount of energy and risk of mortality required to migrate if it was not necessary to survive," said Matt Giovanni, a research biologist with the Peregrine Fund in Idaho.
"Their cyclic, irruptive, southward migrations are almost certainly caused by cycles in lemming populations," he said. (More information on the relationship of lemming populations and snowy owl nesting can be seen at www.startribune.com/a866.)
In Minnesota, snowy owls have been reported from near the Canadian border to near the Iowa border.
Four have been delivered to the Raptor Center at the University of Minnesota, according to Dr. Julia Ponder, executive director. Three of those birds died, two otherwise healthy adults from injuries, one juvenile from starvation.
"The birds are looking for lemmings," Ponder said. "They can't find them and they starve."
Driving along roads through Minnesota farmland could be one way to catch a glimpse of these owls. You can check on U.S. reports, including Minnesota, at www.startribune.com/a867.
Or, just keep an eye on high perches in your neighborhood. Urban sightings of these beautiful birds are hardly unknown.
If you see an owl, keep a respectful distance. Don't approach or disturb the bird. It could be having more trouble than it needs already.