Snowy Owl

The snowy owl is the owl of the far north — a big, heavily feathered predator that hunts in daylight across treeless tundra and ties its entire life cycle to the boom-and-bust of a small rodent.

Overview

Snowy owls breed on Arctic tundra right around the pole, in northern Canada, Alaska, Greenland, Scandinavia, and Russia. They are birds of wide open space: flat, grassy or rocky ground with a clear view and low perches. In winter, some stay in the Arctic and others move south, unpredictably, to open landscapes that echo the tundra — coastal dunes, prairies, marshes, and, famously, airfields.

Physical characteristics

Snowy owls are built for cold. They are among the most densely feathered birds in the world, with thick down and feathers covering the legs and feet like fluffy boots, and they carry a heavy fat layer. At 1.6–2.9 kg they are the heaviest owl in North America and one of the largest owls by weight anywhere.

Plumage ranges from the near-pure white of old males to the boldly barred brown-and-white of females and juveniles. The eyes are golden yellow, and unlike most owls the snowy owl has a rounded head with no ear tufts.

Diet and hunting

The snowy owl is, above all, a lemming specialist. On the breeding grounds an adult eats three to five lemmings a day and may take more than 1,600 in a year. When lemmings crash, snowy owls switch to voles, Arctic hares, ptarmigan, ducks, and seabirds, or simply do not breed that year.

They hunt from a low perch — a hummock, a fence post, a piece of driftwood — scanning and listening, then gliding out on silent wings to snatch prey with their talons. In continuous summer daylight they must be able to hunt at any hour, so, unusually for owls, they are active by day.

Reproduction and the lemming cycle

Snowy owl breeding is dictated by rodents. In a good lemming year a female lays a large clutch — up to 11 eggs — in a shallow scrape on a raised, snow-free rise. In a poor year she may lay three, or none. The male provisions the female and chicks, and both parents defend the nest fiercely against Arctic foxes, jaegers, and wolves, even attacking caribou and people that wander too close. Chicks leave the nest before they can fly and scatter to hide among the tundra while the parents keep feeding them.

Because lemming populations in any one area peak roughly every three to five years, snowy owls are nomadic, shifting their breeding sites across the Arctic each year to wherever the rodents are abundant.

Threats and conservation

The snowy owl is listed as Vulnerable and declining:

• Climate change. Warming is making Arctic snow conditions less predictable, which appears to be dampening or desynchronising the lemming cycles the owls rely on to reproduce.
• Collisions. Wintering owls, especially inexperienced young birds, are killed by vehicles and aircraft when they settle on roads and runways.
• Prey disturbance and contaminants across the range, and disease.

Because snowy owls range across remote territory in low densities and move so much between years, they are hard to count and monitor — part of why their recent reclassification as Vulnerable surprised many birdwatchers.