It begins up north, as a few reports around late October: Snowy owls sighted. Sometimes it builds slowly, sometimes suddenly, with reports coming in from New England, from Minnesota. Every three to five years, around December, January, and occasionally early February, what began as a flurry becomes a blizzard of snowy owl sightings—sometimes as far south as southern California and Florida.
One of the biggest years on record was the winter of 1926–27. Estimates were that five thousand snowies were shot in the United States that winter, and observations were recorded as far south as North Carolina and West Virginia. This event—the periodic southward movement of owls en masse—is so startling, so puzzling, that it is called an irruption.
No one knows what causes so many of these big, white Arctic owls to come south. But this is not the only mystery about the snowy owl. Flying during the day—“like a huge white moth,” in the words of one naturalist—the snowy is a predator of uncanny powers, with senses so sharp they seem to defy explanation.
Snowy owls appear at times and places you would least expect to see an owl. They will hunt in daylight. They don’t like trees, preferring open areas instead, like beaches and fields and airport runways—flat areas that must remind them of their native tundra. They often sit on the ground, sometimes for hours.
Few birds are more exciting to see. Huge and gorgeous, standing up to twenty-eight inches tall and weighing about five pounds, an adult female snowy is a third bigger than a great horned owl. The mostly white plumage of the adult females and youngsters is chevroned with brown, but adult males are dazzlingly snow-white.
“The most amazing thing is their eyes,” says Ross Lein, a University of Calgary professor who has studied snowies for years. “These brilliant yellow eyes in this white face, surrounded by jetblack eyelids—it’s spectacular. They put a stare on you like nothing else.”
They are waiting for prey. Field ornithologist Simon Perkins of Massachusetts Audubon calls the snowy “the supreme predator.” Most owls hunt on silent wings, surprising prey in the dark of night. Not the snowy. Hunting in the open, like a falcon, the snowy owl swoops on its prey and takes it in flight. It can muscle big Canada geese, fat raccoons, even great blue herons; yet it can also delicately snatch a tiny snow bunting.
Norm Smith, director of Blue Hills Trailside Museum in Milton, Massachusetts, has been studying snowies at Boston’s Logan Airport since 1981, and still he sometimes can’t believe his eyes. Once he spotted an owl across the water in Winthrop, so far away that the bird was only a speck in his binoculars. His young daughter insisted they try to trap and band the owl. To appease her, Smith baited a trap with a pigeon, even though he was sure the owl would never see it. The owl flew right to the prey.
Another time, Smith chose to use a starling as a lure to capture an owl sitting on the landing lights at the airport. A jet was taking off as Smith prepared to place the starling in the trap. The starling squawked. The owl swiveled its head. Even over the jet engines’ roar, the owl had heard the starling.
Perhaps because of the snowy owl’s unusual powers, Ice Age people believed it was a magical creature. In the caves at PessacsurDordogne, France, inhabited by European tundra-dwellers twenty thousand years ago, anthropologists have found thousands of snowy owl claw bones. It is thought the bones were used as magic charms.
Even today, many people believe that owls possess special powers. A Native American saying holds that seeing an owl foretells a change. But what change drives the snowies south in such numbers?
For years, many naturalists believed the mass southern excursions followed a crash in the population of Arctic lemmings. (These tundra-living voles are the ones that commit suicide on cue for TV cameras. Actually, lemmings don’t toss themselves over cliffs out of despair. But they do mass migrate, and if the leaders make a wrong turn—like over a cliff—the followers don’t figure it out till it’s too late.) When the snowies ran out of rodents, it was thought, they went south in search of other food.
The idea that lemming numbers drove owl irruptions stemmed from a 1940s paper correlating lemming numbers in Churchill, Manitoba, with snowy owl irruptions in New England. The problem with the study, Professor Lein points out, was that there are no snowy owls in Churchill.
Another theory is that bad weather might drive the birds south. During light snow years with lots of ice, there may be plenty of rodents, but the birds can’t get at them very easily. Owls are known to dive through powdery snow to grab tunneling rodents, but they can’t crack through crusty ice. In the winter of 1992, for example, Ottawa reported a particularly icy winter, and New England received a blizzard of snowies—forty of them in Vermont alone, the highest number ever recorded there.
Like the lemming idea, this theory casts the visiting owls as starving nomads—but in 1992, the dozens of birds Smith examined at Logan Airport were all fat and healthy. He offers a more optimistic scenario: Perhaps rather than telling of a bad winter, the owls’ appearance recalls a good summer; perhaps when an unusual number of snowy owlets fledge, some must come south as “overflow.” Sure enough, a high number of the owls reported during irruptions are immatures.
But no one really knows. No one even knows where in the vast Arctic they come from. The strong-winged snowy owls migrate singly and can fly enormous distances. In 1945, two snowies landed on a ship following a circular route between Gibraltar and New York, some 1,300 miles from New York and 320 miles from Newfoundland. There are records of Asia-breeding snowies turning up as far south as Iran.
One incredibly lucky researcher was able to get reports on the whereabouts of three out of five hatchlings he had banded from one nest at Cambridge Bay, Victoria Island, British Columbia. Within a year, one was recovered along the southern Hudson Bay coast. Another was found in eastern Ontario. A third was in Siberia.