Boreal Owl Biology

A Reference for North and Central American Owls

Name: Boreal Owl – Aegolius funereus
Other Common Names:  Arctic Saw-Whet Owl; Funeral Owl; Richardson’s Owl (richardsoni); Tengmalm’s Owl (funereus); Sparrow Owl.

Subspecies: TIn North America there is only one accepted race of Boreal Owl. There are five other races recognized across Europe and Asia. One of these other races, A. f. magnus, is resident in N. E. Siberia and may accidentally show up in Alaska but will not be discussed further here.
A. f. richardsoni is resident from south and central E. Alaska across Canada to the East Coast. Also resident in the Rocky Mountains as far south as Colorado. Light blue area on the map above indicates probable local breeding.

Measurements and Weights:
Wingspan: 19 – 25 in.
Length: 8.5 – 12 in.
Tail: 3 3/4 – 4 1/4 in.
Average Weight: Male: 4.4 oz.
Average Weight: Female: 6 oz.

Description: A small owl lacking ear tufts. The male and female are alike in plumage. The general color of the upper parts are dark brown. The backside has dispersed large white spots. Its crown is thickly spotted with smaller white spots. The facial disk is white with a dark brown border at the sides. Around the eyes is a black border. Below and at the sides of the bill is cinnamon- brown. The chest, flanks, and belly are heavily streaked brown on a white base. The feet are feathered. And its claws are black. Its iris are lemon yellow and its bill is dark grayish-horn with a yellowish tip. The Boreal Owl is usually nocturnal except in the far north when there is no night.

Young: The young are dark chocolate-brown to deep sooty-brown above and below. The facial disk is black. Eyebrows, above (forehead), and along the sides of the bill is white. Sometimes said to have a white “V” on its forehead. The mustache is white (white extends outward from the bill). Iris is yellow.

Habitat:

The Boreal Owl inhabits the northern coniferous and mixed deciduous boreal and subalpine forests of North America. In Colorado they were found to occur between 9,100 and 10,400 ft. elevation although the highest densities were above 9,800 ft. in mature spruce-fir forests where there were numerous subalpine meadows and high populations of red-backed voles. In N. E. Washington, Montana, and Idaho they were found to favor spruce-fir or subalpine-fir above 5,000 ft. elevation.

Food and Feeding:

The primary foods of the Boreal Owl are small mammals, birds, and insects. Voles are its preferred food, which may make up as much as 75% of its diet. It is primarily a nocturnal forager except in the far north where there is continuos light during the summer although it will intermittently forage in daylight hours in the southern latitudes also. It is a “sit and wait” predator. It can locate and capture prey strictly audibly such as beneath the snow or vegetation. Will cache food and can later thaw it if necessary by performing brooding like behavior over it.

Breeding:

The Boreal Owl nests in woodpecker holes (Pileated and Northern Flicker) or nest boxes. Clutch size ranges from 3 – 11 eggs but 4 – 6 are more common. The incubation period is from 25 – 32 days. The young owls fledge at 28 -36 days but remain close (

Movements and Life Span:

In general the Boreal Owl has been thought to be resident in its home range during years when their prey does not become scarce. Recent evidence seems to suggest that the females and young are more migratory and may even have some seasonal movements or migrations. The males are generally sedentary within their territory. Periodic eruptions do occur where large numbers of Boreal Owls move into Southern Canada and the north and north-eastern States. Banded Boreal Owls have been known to live for almost 16 years.