"In October and November, snowy owls started appearing," said Duluth birder Laura Erickson, host of the "For the Birds" radio program.
And, no, they're not starving.
"Most of the owls we get, even in an irruption, are healthy. They're just out of their range," Erickson said.
Snowy owl irruptions are not fully understood, but they typically occur for one of two reasons, Erickson said. The snowy owl population in the Arctic is tied closely to the population of lemmings, one of their main prey sources. In years when the lemming population crashes, many snowies move south looking for food.
In years when the lemming population is high, female snowy owls produce more eggs and hatch more young. Snowies in the Arctic are territorial, and young birds can't compete effectively for food. So, in years of those big hatches, many young birds move south to find their prey.
In this year's irruption, about 90 percent of the snowies appear to be juveniles, the DNR's Brady said.
"This tells you they had really high reproductive success in the Arctic," he said. "They raised lots of babies. Those babies have to go somewhere, and they end up down here."
They'll be here for the winter, then return north in the spring.
Where to see them
Because snowy owls are native to the tundra, they tend to prefer open spaces even when they come south. They're typically seen near airports, the Duluth-Superior harbor or open areas such as fields and bogs, Erickson said. They perch on high places like utility poles, light posts or piles of snow.