PLUM ISLAND — There's been a surge in snowy owl sightings across the nation, and biologists believe the thanks goes to lemmings, those hapless little creatures known for jumping en masse off cliffs.
At least two snowy owls have been spotted with regularity on Plum Island and Crane Beach in Ipswich over the past few weeks, most recently near parking lot 5 in Parker River National Wildlife Refuge. They have drawn an enthusiastic following of birdwatchers wanting to catch a glimpse of the strikingly handsome birds.
"It's one of the really big deals in this area in the winter," said David Larson, education coordinator for Mass Audubon's Joppa Flats Education Center in Newburyport. "The snowy owl is always a huge draw. People love to see them.
"People are constantly coming through here asking what the latest information is."
As striking as owls can be in appearance, snowy owls are notable even among their own kind. Their eyes are bright yellow, and their feathers are pure white with a pattern of short, squiggled black lines that give them some camouflage on tree limbs. They can range in height up to 28 inches, with 5-foot wingspans.
Snowy owls have recently gained some fame in popular culture. In the Harry Potter books and movies, Harry's owl sidekick, Hedwig, is a snowy.
Snowy owls' main habitat is the Arctic, but they are known to migrate south in pursuit of food. This year's unusual migration is believed to be related to lemmings — rodents that vary between 3 and 6 inches long and are commonly found in the Arctic. Like all rodents, they tend to experience population booms and busts. 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.
The U.S. Fish and Wildlife Service reported that snowy owls have been spotted in unusually, and perhaps historically, high numbers across the nation, from Washington State in the West to Plum Island in the East. They have been sighted as far south as Kansas.
"This has certainly been a good year. Crane Beach has been the local hot spot," Larson said.
Larson said the number of snowy owls seen locally thus far is about average for Plum Island, although in some years — like last year — there were none.
"Two is not unusual. Three or four is really good," Larson said.
A third owl appears to have been found. Larson noted that a dead snowy owl was recovered on the northern end of Plum Island and brought to the refuge headquarters for examination.
Birdwatchers will need to change their habits slightly in order to spot the snowy owls. Larson said the usual place to look for them is the salt marsh, but this year, it's much easier to spot them sitting on the dunes.
"The portent of that is not clear," he said, noting that the owls might be warming themselves on the sand or digesting.
There's plenty of food for the owls here. They're known to kill mice, as well as ducks, which have been in abundance due to the lack of ice. They've even hunted and killed a great blue heron, a bird that stands 4 feet tall.
As for lemmings, their long-held reputation for committing mass suicide by marching off cliffs has been disproved by biologists. When lemming populations surge and food supplies dwindle, they mass migrate to new territory, which sometimes involves attempting to leave their overpopulated land by plunging into the frigid Arctic waters in an attempt to swim to a less-populated place.
The lemming myth was popularized by a 1950s Disney nature movie that depicted lemmings casting themselves off a cliff. Decades later, a Canadian Broadcast Company probe found that the scene had been contrived by Disney filmmakers by placing the lemmings on the edge of a cliff and pushing them off with a mechanical device.