Snowy owls (Bubo scandiacus) are Arctic owls, but some migrate to more southern territories from November to March. During this time, you might spot one in open, treeless coastal areas of Massachusetts. One was spotted in Assembly Row in 2015, and another in West Medford in 2022. They have also been spotted in South Boston.
There are more snowy owl visitors in some winters than others. Occasionally these golden-eyed birds come down from their breeding grounds in the north in tremendous numbers. The number of snowy owls born in a season depends on how much food the parents can find in the Arctic. Snowy owls eat mostly the small, short-tailed rodents known as lemmings. If there are not many lemmings, some owls will not breed at all, and others will lay fewer eggs. In years in which the lemming population soars, female owls lay more eggs and more chicks hatch. These are boom years, called irruptions.
Since 1882, there have been 26 such years; the latest was in 2013–2014.
During irruption years, all these young snowy owls spread out to find good territories for the winter and have been seen as far south as Texas, Florida and Cuba.
Smaller population bumps occur every four or five years. In 2021, a snowy owl visited Central Park in New York City – for the first time since December 1890. According to Norman Smith, a raptor specialist at Mass Audubon, this winter is turning out to be an average year for snowy owls.
You might be surprised to learn that the largest concentration of snowy owls in the Northeast is around Logan Airport. These birds like Logan Airport because it resembles Arctic tundra – flat and treeless (and teeming with rats and voles). It is also surrounded on three sides by water, and in addition to eating small mammals, snowy owls eat waterfowl small and large, including ducks, geese, herons, gulls and cormorants. Snowy owls begin arriving at the airport in early November and leave in early April; one will occasionally stay around all year.
Snowy owls swallow small food whole. It goes into the gizzard, where digestive fluids and grit grind and dissolve the muscle, fat, skin and organs. Indigestible bits of fur, teeth or bones are compressed into a pellet that the owl spits up 18 to 24 hours after eating. The pellet blocks the entrance to the gizzard, so a pellet must be regurgitated before an owl can eat again. When eating larger prey, such as a duck, the owl plucks the feathers and eats only the breast. (If you study owl pellets to determine its diet, be aware that not all prey will show up in the pellets.)
Because Logan’s snowy owls are a threat to aircraft, Smith is on a mission to capture them using a bow net and a rodent-baited cage. To capture one, Norman sets his trap and waits (often in the dark) in a nearby vehicle that acts as a blind. It can take five or six hours to lure an owl. This is not a job for an impatient person. When the owl finally jumps on top of the cage, Norman pulls a 150-foot string on a fishing rod to trigger the net and capture the owl.
In the irruption year of 2013, he captured 121 owls at the airport. On average, he catches eight to 10.
Capturing owls might seem like an exercise in futility, a Sisyphean task, but it works. Relocated birds rarely return to the airport. In one study, only 17 of 452 relocated snowy owls were recaptured at Logan airport – and those recaptures were all in later years.
Since 1981, Smith has captured more than 900 snowy owls and released them in remote locations. By putting transmitters on some, he has learned that snowy owls can fly as fast as 82 mph and fly as high as 8,000 feet. In nine months, one owl flew more than 7,426 miles.
In the Arctic, snowy owls hunt at irregular times during daylight hours – they have no choice, since it is light almost 24 hours per day at the height of summer. Lemmings, their main prey, are active day and night. In the winter in our area, snowy owls tend to hunt more at dawn and dusk and at night, just like other owls. They rest, perched on a bump on the ground, to conserve energy during most daylight hours.
Snowy owls have eyes that are almost the same size as ours despite the birds weighing only 4 to 6 pounds. This gives you an idea of how important vision is to them. Owl eyes are large to help them see well in low light and from great distances. A snowy owl can spot a mouse from a football field away. Owls also have the largest brains of any bird, which probably co-evolved with the large eyes to help them see and hunt well. Snowy owls cannot move their eyes in the socket, though. Because they can look only straight ahead, owls compensate by having a flexible neck that allows them to turn their head 270 degrees and almost upside down.
Snowy owls are not snowy white in color: Though males tend to be white, females tend to have more brown markings (as well as being larger). Like all birds, snowy owls have feathers. To stay warm in temperatures as low as minus 80, they have fine, furlike feathers even on the beak, legs and feet.
Many owls die from colliding with cars, being electrocuted on power lines or ingesting rat poison. Toxicology testing of dead owls shows that rat poisoning is an increasing cause of death in the Northeast, and if these dangers weren’t enough, three years ago snowy owls in our region began dying from bird flu. (Waterfowl have been hard hit by bird flu, and snowy owls eat waterfowl.)
Snowy owl populations are declining rapidly, according to recent data. It is estimated that there are only about 5,000 to 7,000 breeding pairs in North America. Global warming also threatens them. A shift to warmer, wetter winters can lower lemming populations, which then limits the snowy owl population.
If you are along the coast in the winter, especially in flat, treeless areas, keep your eyes peeled. You might spot a snowy owl at rest. Stay at least 150 feet away, and if it fully opens its eyes, back off immediately. Snowy owls need to conserve their energy, and if disturbed too much, they may not survive the winter.
Reader photo
Teresa McCraw spotted this Cooper’s hawk in Clarksville, Tennessee, on Sept. 22.
Have you taken photos of our urban wild things? Send your images to Cambridge Day, and we may use them as part of a future feature. Include the photographer’s name and the general location where the photo was taken.
Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.
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Thank you, Jeanine, for your comprehensive and beautifully written articles. I learn so much from reading them and admire your passion for and dedication to all creatures.