LAKE ANDES, S.D. - Famous for its role as Harry Potter's companion in the books and movies, a species of majestic, mostly white owls is being sighted in abundant numbers this winter far from both Hogwarts and its native Arctic habitat.
It's typical for snowy owls to arrive in the U.S. every three or four winters, but this year's irruption is widespread, with birders from the Pacific Northwest to New England reporting frequent sightings of the yellow-eyed birds. As many as 30 were spotted in December around South Dakota's Lake Andes.
"Thirty in one area, that's mind numbing," said Mark Robbins, an ornithologist with the University of Kansas Biodiversity Institute.
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 are drawn to frozen lakes, which remind them of their tundra back home in the Arctic, Robbins said.
"And if they're finding rodents there, they're staying there," he said. "And perhaps seeing a couple of more snowy owls there, they may think, 'OK, this is a hot spot.'"
The owls have been regular visitors to Boston's Logan Airport, and one even showed up just after Thanksgiving in Hawaii. Chicago's Montrose Point Bird Sanctuary has become a haven for the creatures, with "countless sightings" this season, said Matthew Cvetas, an Evanston, Ill., birder.
"It's just been really incredible," he said.
Cvetas said owl sightings are exciting for birders, as the creatures are mostly nocturnal and difficult to spot. Though snowy owls hunt day and night, the allure of their plumage helps make them a prize sighting.
"Here's the largest North American owl in terms of weight, a near all-white ghost of a bird for an adult male," said Cvetas, who has spotted four snowy owls since November. "For me, it symbolizes wilderness at its best."
Birders spotted three snowy owls sitting on an irrigation unit west of Squaw Creek National Wildlife Refuge near Missouri's borders with Nebraska and Iowa, and there have been five of the birds hanging around Smithville Lake just outside of Kansas City.
"In Missouri, I don't think there's ever been two at a single site," he said.
People have always had a fascination with owls, but the book and 2001 film "Harry Potter and the Sorcerer's Stone," in which a snowy owl named Hedwig first appeared as Harry's companion and mail courier, thrust the species in the spotlight. Holt said the movie series helped land the winged creature a December 2002 National Geographic cover story.
"We were inundated with phone calls from people about all these kids wanting to have pet snowy owls," Holt said. "It just went crazy for a while there."
Snowy owls begin life with a mix of white and dark brown feathers. Males, which tend to be smaller, lose their dark feathers as they age, with many winding up pure white. Their lifespan is not known, but Holt estimates that snowy owls can likely survive 10 to 15 years in the wild and three decades in captivity.
There's no good estimate on the size of their population. Holt recalls a study in which researchers working on a Canadian island found thousands of snowy owls one year, only to follow up the next year to find not a single one.
"They're too spread out and they move around too much," Holt said.
Holt said snowy owls are remarkable predators, nearing flying speeds of 70 miles per hour with the ability to attack and eat creatures as large as Canada geese and great blue herons. Yet despite that diverse diet, their breeding seems dependent on a single food source — the Arctic lemming.
He said this year's influx is following in Harry Potter's footsteps to return the snowy owl into the public spotlight, which is great for the species and his research.
"It's wonderful," Holt said. "It's great for snowy owls. It's great PR."