On the Snowy Owl Invasion

Snowy Owls have migrated south in impressive numbers this winter. Unlike some irruptions, which affect one part of the continent but not others, this year's Snowy Owl irruption has been observed across North America. Even Hawaii recorded a Snowy Owl, a first state record (which was promptly shot by airport officials). The New York Times reports on the scale of the Snowy Owl irruption:

The irruption started in late fall and is expected to end by March or April. In few places are people as excited as in Kansas and Missouri, where snowy owls are exceedingly rare. Ninety have shown up in Kansas this winter and 40 in Missouri. Until this year, the highest number counted in Missouri had been eight.

“It’s a massive movement,” said Mark Robbins, the ornithology collection manager at the University of Kansas.

When five of the birds took up residency at Smithville Lake, near Kansas City, Mo., it created an “owl jam,” Mr. Robbins said. Thousands of people have driven there to see them, he said, and hundreds of owl seekers have shown up at Clinton Lake near Lawrence, Kan....

Geoff LeBaron, director of the Audubon Society’s Christmas bird count, said that it was hard to estimate how many snowy owls flew south in this irruption because the latest data has not been tallied, but that the overall number was probably a few thousand. Despite the surge, the society says, snowy owls are thought to have been in decline since 1945.

There is far more data on the scope of this migration than in years past, thanks to a citizen science project based at Cornell called eBird, which is run by the Cornell Lab of Ornithology and the Audubon Society. Bird-watchers around the country call in sightings, which are plotted on a map that shows precisely where the birds are wintering.

“A lot of people who have never seen one before have rushed out and seen multiples,” said Marshall Iliff, an ornithologist at Cornell and the project’s leader. “And photographers are having a field day.”

Additional hot spots include the mouth of the Columbia River in Washington State, with 10 to 13 birds; 20 at Lake Andes National Wildlife Refuge in South Dakota, and 30 in Boundary Bay, near Vancouver in British Columbia.

The owls are even showing up in urban and suburban areas, along highways, on signs and fence posts, and in other places where people can more easily spot them. It has been a good snowy owl year at Logan Airport in Boston, too. Because the airfield looks like tundra, snowy owls tend to flock there, and they must be trapped and removed.

“We’ve removed 21 so far this year, and the average is six,” said Norman Smith, who works for the Massachusetts Audubon Society and traps the birds. The most ever trapped was 43 in 1986, Mr. Smith said, “but the year’s not over.”

To be more precise, birders do not "call in sightings" to eBird but enter sightings through web-based checklist forms on the eBird website. For more on the causes behind this year's Snowy Owl irruption, see this post by David Sibley. He gives a more clear account of what probably happened than The New York Times does.

I have only seen the one Snowy Owl (pictured) that was present at Merrill Creek Reservoir so far this winter. So this winter has not been quite as memorable for me as the winter of 2009, when I saw four Snowy Owls over the course of the winter, or the winter of 2010, when I saw two Snowy Owls at Parker River NWR in Massachusetts during the Superbowl of Birding.