One of the most interesting and iconic winter visitors in Massachusetts is the snowy owl. With a wingspan of close to 5 feet and weighing up to 6½ pounds, snowy owls are the heaviest owl species in North America. And with their white feathers and piercing yellow eyes, they’re certainly one of the most beautiful.
Snowy owls typically begin to show up here in November and depart for their Arctic breeding areas by the end of April. They leave the Arctic tundra in northern Quebec and other parts of eastern Canada to spend the winter in places like the Cape and the Islands, Duxbury, Crane’s Beach, Salisbury Beach, and Plum Island. Some of them even hang out at Logan Airport, seemingly unfazed by the sound of jets taking off and landing.
“Snowy owls are looking for open areas,” said Wayne Petersen, Mass Audubon’s director of the Massachusetts Important Bird Areas program. “Areas that resemble their home in the Arctic tundra — like Logan Airport — no trees and flat. Lots of waterfowl to eat in the salt marshes, and grass at the edge of the taxiways to get rats and mice.”
One winter there were 49 snowy owls at Logan, said Petersen, but some winters there are only a few owls.
Although snowy owls can occasionally be found inland in open areas like farm fields, they mostly like the coasts where they can hang out in sand dunes and salt marshes, Petersen said.
Snowy owls are found throughout the Arctic, and move around a lot across the Russian and Canadian Arctic.
Snowy owls are considered an “irruptive” species, said Petersen, one that periodically responds to changes in food supply on its home territory by moving elsewhere. During the Arctic summer, snowy owls feed primarily on small rodents called lemmings.
Lemming populations go through cycles of boom and bust every few years, and these cyclic changes in the local abundance of food periodically influence snowy owl winter movements.
Norman Smith, a researcher with Mass Audubon’s Snowy Owl Project and former director of the Blue Hills Trailside Museum, determined that most snowy owls show up in New England after an Arctic lemming population boom. When food is plentiful the owls breed more successfully and produce more offspring.
“When there are lots of offspring produced, it’s probably like a case of let’s get the kids out of the house!” said Petersen. “The excess of young owls are ultimately hassled by their parents and other adults in the population to leave their territory.”
New England isn’t the only US destination for snowy owls in the winter. Some owls head south from other parts of the Arctic and spend the winter in the Great Plains, Great Lakes states, or Pacific Northwest, said Petersen.
Many snowy owls remain in the Arctic during the winter, said Petersen, where they feed on sea ducks and ptarmigans, a species of bird.
The Cornell University website “All About Birds” estimates a global breeding population of about 200,000 snowy owls, with around 24 percent wintering in the United States.
Snowy owls nest on the ground in the Arctic tundra, laying from two to 14 eggs, depending on the availability of food supply, said Petersen. The females scrape out a depression on the ground to lay their eggs, typically on a mound or tussock. The female stays at the nest, while the male hunts and brings food to the nest for the female and chicks.
Their nests are potentially vulnerable to predators, said Petersen, but snowy owls are fearsome birds and will go after potential nest predators like ravens and foxes.
The Cornell website said that snowy owls have been known to dive-bomb and strike at humans, and there was one report of a snowy owl attacking a pair of arctic wolves.
Male and female snowy owls can be difficult to tell apart, said Petersen, but most females have dark barring, while males are typically much whiter, and devoid of dusky markings.
Snowy owls usually mate for life, said Petersen, and are thought to live about 10 years or more in the wild. There is a record of a captive snowy owl living to 28 years old, he said.
Snowy owls are protected by law, but they still suffer mortality from illegal hunting, vehicle collisions, and being poisoned by rodenticides, said Petersen.
Because snowy owls like to hang out at airports, collisions with jets or getting caught in the backdraft of jets can be a source of mortality for the birds as well, said Petersen, and a potential problem for aircraft.
Smith has been trapping snowy owls at Logan Airport for many years, and relocating them to Duxbury Beach and Plum Island, Petersen said. And Smith helped airport officials in New York to develop a snowy owl trapping and relocation program at Kennedy Airport.
Petersen said Plum Island and Salisbury are the best bet for seeing snowy owls in Massachusetts in the winter.
“There are always bird watchers up there,” said Petersen. “Just ask the bird watchers where the owls are.”
Don Lyman is a biologist, freelance science journalist, and hospital pharmacist who lives north of Boston. Send your questions about nature and wildlife in the suburbs to email@example.com.