Boreal Owl Life History

Habitat

Habitat Forests

Boreal Owls occur in stands of spruce, aspen, poplar, birch, and fir in the vast boreal forest that stretches across much of northern North America and Eurasia. They also occur in high elevation mountains with subalpine forests in Canada and the western U.S. In the winter, they forage in spruce-fir forests where uncrusted snow under the trees facilitates access to prey. In spring, they often forage in clearcuts and agricultural fields where small mammals are easier to locate.

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Food

Food Mammals

Boreal Owls eat small mammals, birds, and insects. Small mammals in their diet include voles, mice, shrews, and squirrels. They hunt at night, except in the far north where the sun doesn't set in the summer. From hunting perches, they sit and wait for prey before attacking it with their talons. Like other owls, they cough up pellets of indigestible bones and fur, usually once a day.

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Nesting

Nest Placement

Nest Cavity

Boreal Owls nest in older stands of mixed-conifer forests, but also in nest boxes in younger forests. The male advertises 1–5 nest sites within his territory, from which the female chooses.

Nest Description

They nest in holes in trees (cavities) created by woodpeckers or in natural holes. They also nest in nest boxes.

Nesting Facts
Clutch Size:1-19 eggs
Number of Broods:1 brood
Egg Length:1.3-1.4 in (3.2-3.5 cm)
Egg Width:1.0-1.1 in (2.5-2.7 cm)
Incubation Period:26-32 days
Nestling Period:27-36 days
Egg Description:

Dull white.

Condition at Hatching:

Eyes closed and covered in white down.

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Behavior

Behavior Aerial Dive (ground/talons)

When attacking prey, Boreal Owls glide down to the ground and grab it with their talons. Boreal Owls are solitary birds, even during the breeding season. Mated pairs don't roost together and typically only meet up at the nest site during courtship and feeding. The male courts the female with song and food, feeding her for up to 3 months prior to nesting. He continues to bring food to the female throughout the nesting period. Males and females form monogamous bonds in North America for a single breeding season. In Europe males sometimes mate with more than one female and can produce more than one brood per season, unlike the single-brooded pairs in North America. Males sing to maintain their territory, but they only defend the area surrounding the nest cavity, not the entire foraging territory.

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Conservation

Conservation Low Concern

Boreal Owls are uncommon and infrequently encountered. Their boreal range and nocturnal habits mean that their populations are not surveyed by the North American Breeding Bird Survey and little is known about population trends. Partners in Flight estimates the global breeding population at 1.7 million. The species rates a 10 out of 20 on the Continental Concern Score, which means it is not on the Partners in Flight Watch List and is a species of low conservation concern.

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Backyard Tips

If you live within the breeding range of a Boreal Owl, consider putting up a nest box. Boreal Owls readily accept nest boxes, just make sure you put it up well before breeding season. Head on over to NestWatch where you'll find plans to build a nest box sized just right for a Boreal Owl.

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Credits

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Hayward, G. D. and P. H. Hayward. 1993. Boreal Owl (Aegolius funereus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love (2016). Longevity records of North American birds. Version 2016.1. Patuxent Wildlife Research Center, Bird Banding Laboratory, Laurel, MD, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Pieplow, N. (2017). Peterson field guide to bird sounds of eastern North America. Houghton Mifflin Harcourt Publishing Company, NY, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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