Northern Hawk Owl––Another owl on the prowl for voles

Boreal owls, the subject of the last Birder’s Notebook article, are not the only unexpected owl to spice up the winter bird scene in parts of this region. Bold and charismatic, northern hawk owls also have come from interior forests in search of food.

A scarcity of voles in Alaska’s interior has apparently prompted both species to venture westward and onto the Seward Peninsula to prospect for prey beyond their normal range.

Hawk owls are an unusual and surprising owl in a number of ways. As suggested by their name, these mid-sized owls have some striking similarities to hawks and falcons in appearance and behavior.

Unlike most owls, hawk owls hunt in the daytime and use sight as well as keen hearing to find prey. Most owls hunt at night and have soft edges on their wing feathers for stealthy, silent flight. Not so the hawk owl, whose stiff wing feathers make some noise but enable fast and powerful daytime flight.

The face and piercing yellow eyes of a hawk owl are all owl, but look further and characteristics of other raptors emerge. Perched in its classic pose atop a tree or other high perch scanning for prey, the hawk owl’s body shape is more streamlined than that of most owls. That, and its long tail, combine to give this owl a hawk-like look.

Most owls have large, rounded wings and buoyant, moth-like flight. In contrast, a hawk owl has pointed wings like some hawks. Its flight styles vary from fast and powerful wing-strokes like a falcon, to maneuvering agilely through the trees like a goshawk, or it may hover like a kestrel.

Hawk owls are found in boreal forests (taiga) around the northern hemisphere. Or they may inhabit tundra areas where streams are lined by trees. These owls need a combination of open areas for hunting, and trees where they nest and roost. The hawk owl is not adapted to dense forest habitats where boreal owls live.

Hawk owls are fairly common in Alaska’s interior forests, but their numbers fluctuate with the ups and downs of vole population cycles. In this region, hawk owls are rare visitors, seen sporadically, most often outside of the breeding season.

Like the boreal owl, northern hawk owls are normally year-round residents of the boreal forest. However, when cyclic vole populations plummet, these usually nonmigratory owls may seek prey far beyond their normal range.

Irruptions are most likely when the scarcity of prey coincides with severe winter conditions, following a highly successful breeding season. During irruptions hawk owls may be found almost anywhere in Alaska, including on the Seward Peninsula.

Sometimes, these nomads move south into southern Canada and the northern United States in search of prey, as they did this year. This seldom-seen, unusual-looking owl that often shows little fear of people, generates huge excitement among bird enthusiasts and photographers.

Red-back voles are the hawk owl’s food of choice. Lemmings, shrews, other mammals as large as hares, and birds as large as grouse and ptarmigan are a smaller part of the hawk owl’s diet. In summer insects and small fish may be added to their menu.

These daytime hunters with keen eyesight and excellent hearing are often seen sitting at the top of a tree or other prominent perch, where they watch and listen for prey.

Their hearing is not as well developed as it is in night-hunting owls, which have larger facial discs to direct sound to their ears, and asymmetrical ear openings for precisely locating hidden prey. Regardless, they are able to detect rodents moving up to 12 inches beneath the snow, and pounce precisely to catch them using hearing alone.

When prey is detected, the owl swoops down, flying low to the ground with fast, strong wingbeats, grabbing its meal with strong feet and sharp talons. Or they may fly low over the ground searching for food, hover over prey before striking, or snatch birds in flight. If prey is plentiful, they may catch small mammals to cache in the trees to eat later.

Hawk owls do not build their own nests. Instead, they use woodpecker holes, natural cavities in trees, the decaying tops of broken off tree trunks, or occasionally abandoned stick nests of other raptors or ravens. If hawk owls nest in this region, I am not aware of it.

Hawk owls are one of the least studied birds in North America. They occur at low densities in vast and remote northern forests, making research difficult.

They have few predators besides great horned owls, and northern goshawks. Lack of nesting sites can limit their numbers, which fluctuate naturally with the boom-and-bust cycles of their prey. Their population trend is unknown.

Northern hawk owls can be unusually tolerant of people and human activity. When they show up sporadically in the Nome area, they can be quite a road-side attraction, posing obligingly for photos while perched on markers and signs. Keep a look-out, owls on the prowl for voles may be headed this way.