Consensus: Snowy owl invasion caused by boom of Arctic lemming population in 2011; it was also caused by the *bust* of the Arctic lemming population in 2011

Harry Potter's owl spotted across U.S. - TwinCities.com

[January 6, 2012] The arrival of the birds, which can top 2 feet in height with a wingspan of nearly 5 feet, is the result of a plentiful population of Arctic lemmings this summer, which led to a strong breeding season, said Denver Holt, director of the Owl Research Institute in Charlo, Mont.

Lemmings are snowy owls' main food source, and the baby boom is sending many of the youngsters across the border to scrounge for voles, field mice, rats, rabbits and shore birds.

"It's very unusual, because it's coast to coast," said Holt, who has been researching the owls' Arctic habitat for 25 years.

Snowy owls' visit causing stir with birders » Local News » NewburyportNews.com, Newburyport, MA

[January 6, 2012] Biologists believe the lemming population is undergoing a bust, sending snowy owls far south in search of food, such as field mice and ducks.

"The migration usually means the food supply is in bad shape up north, and that usually means lemmings," Larson said.

The Arctic National Wildlife Refuge, which supports a large snowy owl population, also attributes the unusual southern migration to the lemming dilemma.