Boreal owls are solitary animals, and do not communicate often with other boreal owls except during the breeding season. In order to attract a mate, a male will sing and also making flying passes past females. After leaving the nest, young will call out to their parents with a begging call when they are hungry. Other calls include a warning call used by both sexes as well as a call used by the male to let the female know he has brought food to the nest. Boreal owls will also snap their bill together as a warning when they feel threatened.
Boreal owls perceive their environment visually, acoustically, and chemically. They have keen eyesight, especially in the dark, and can detect prey by prey-generated sounds. Boreal owls, like most owls, have an asymmetrical external ear structure that makes it possible for them to precisely locate prey using only prey-generated sounds. They can hunt for prey completely hidden under snow cover.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Aegolius funereus is not endangered. They are rarely hunted by humans because of their small size. Further, humans don’t kill its prey, so it has a fairly stable food source. The only real impact made by humans on the species is destruction of habitat by harvesting trees for lumber. Nest boxes are sometimes placed on trees to provide nest sites. Since boreal owls are considered migratory, they are protected by the US Migratory Bird Act.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of A. funereus on humans.
Aegolius funereus has very little impact on humans, aside from its role as a predator of small mammals which humans might consider pests.
Positive Impacts: controls pest population
Boreal owls are thought to be one of the most important avian predators of small mammals, such as voles and mice, throughout their range. More than 90% of their diet comes from this source. They are also, as noted above, a prey animal for several other species.
Boreal owls are carnivorous. They feed primarily on small mammals, such as voles, mice, chipmunks, and squirrels. In North America, they have been observed preying on red-backed voles (Myodes gapperi), heather voles (Phenacomys intermedius), jumping mice (Zapus), northern pocket gophers (Thomomys talpoides, and northern flying squirrels (Glaucomys sabrinus). Boreal owls have also been hunting insects and small birds, such as dark-eyed juncos (Junco hyemalis), American robin (Turdus migratorius), and common redpolls (Carduelis flammea). Females may prefer larger, mammalian prey and males may specialize on hunting smaller mammals and birds. During the winter and breeding season boreal owls cache food in rock crevices or tree branches.
When hunting, boreal owls sit on a perch and wait for prey to scamper into sight. They usually select a perch that is bare below, but provides good cover overhead, so that it is more difficult for predators to spot them. Once they have spotted prey, they descend slowly, grasp the prey with their claws, bracing themselves against the ground for leverage. They kill prey with a quick bite to the head or neck. Boreal owls typically eat prey on a perch.
Animal Foods: birds; mammals; insects
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Eats terrestrial vertebrates)
Aegolius funereus can be found in subalpine and boreal forests across the northern hemisphere, including the Neartic and Palearctic regions of the globe. Its range generally follows the northern forest belt.
In North America, where they are known as boreal owls, the range extends from Alaska to eastern Canada.
In Eurasia A. funereus is called Tengmalm’s owl. In Europe they are found mostly in Scandinavia, though there are several scattered populations also found in subalpine forests in the central mountain regions. The range of Tengmalm’s owls extends eastward from Scandinavia, stretching across virtually all of northern Siberia, as they inhabit the taiga lowlands. Their range dips south as it approaches the Pacific Ocean, occurring throughout forested mountains north of the Korean Peninsula.
Biogeographic Regions: nearctic (Native ); palearctic (Native )
Other Geographic Terms: holarctic
Aegolius funereus occur almost exclusively in coniferous forests. However, they are also found in areas of deciduous forest. Dominant tree species in these forests include Engelmann spruce, black spruce, white spruce, aspen, poplar, birch, and balsam fir. They are usually found in dense forests, they seem to avoid areas that are more exposed.
In North America, boreal owls are found from 1580 m to over 3200 m. They occur as low as 1100 m in Central Europe and as high as 2000 m in Siberia. However, during extreme weather, Tengmalm’s owls have been observed as low as 400 m.
Range elevation: 400 to >3200 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: taiga ; forest
The longest known lifespan for a boreal owl is 16 years, from several banded individuals in various studies. In Finland, a study was done to determine the survival rate of A. funereus. Only 50% of first year males survived, while 67% of adult males survived annually. Other studies have put adult survival at 72% and 62% respectively. Yet another study determined that 78% of fledgling males died before they reached sexual maturity.
Range lifespan
Status: wild: 16 (high) years.
Average lifespan
Status: wild: 3.4 years.
Average lifespan
Sex: male
Status: wild: 11.0 years.
Aegolius funereus individuals are small owls with large, rectangular heads and long wings. Males are typically between 21 and 25 cm in length, while females are slightly larger, being between 25 and 28 cm. Like most owls, they have an obvious, light colored facial disc. The head is covered in brown and black mottled feathers. The bill is whitish-yellow, in contrast to the black bill of the northern saw-whet owl. The underparts are white, while the back and wings are predominantly dark brown with lighter spots. The legs are covered in white feathers to the claws. Aegolius funereus is unique from all other owls in that, when the tail is closely folded, there are 3 rows of white spots visible on the dorsal surface. Females are larger than males, weighing 132 to 215 grams, while males weight from 93 to 139 grams. Wing spans are between 55 and 58 cm in males and between 59 and 62 cm in females.
Young are similar in appearance to adults, with more muted colors.
Range mass: 93 to 215 g.
Range length: 21 to 28 cm.
Range wingspan: 55 to 62 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
The primary predators of adult and fledgling boreal owls are other owls and hawks. Included in these are: Accipiter cooperi (Cooper's hawks), A. gentiles (northern goshawks), Buteo virginianus (great horned owls), Strix uralensis (Ural owls), and Strix aluco (tawny owls). All of these predators hunt boreal owls from the air. When they sense a predator nearby, boreal owls will shrink away into a concealment position, remaining motionless and as small as possible to prevent from being seen.
Martens (Martes) are the primary predators of eggs, owlets, and adult females in the nest. Red squirrels (Tamiasciurus hudsonicus) are also probable egg predators.
Known Predators:
Anti-predator Adaptations: cryptic
Aegolius funereus is primarily monogamous. However, there have been documented cases of both bigyny (one male with two mates) and biandry (one female producing two clutches by two different mates). These cases have been observed only in Eurasia, and only when food is extremely plentiful. Males don't defend large foraging territories, but rather nest sites (old woodpecker holes), which are often in short supply. Fights between males have not been observed, and it appears that they compete for females through song and flight. Males will fly between perches near females, and sing a courtship song to attract female interest. If a female is interested, she will inspect the nest and, if she accepts it, she will simply stay there. The courtship period might last anywhere from 2 to 6 weeks for individual owls and from 1 to 4 months for the population as a whole.
Mating System: monogamous
Breeding season is variable, but takes place most commonly from March to June. Clutch size varies with food availability, but is typically around 4 or 5. Eggs are laid once every two days and brooding begins with the first egg, so hatching is asynchronous. Incubation is typically 28 days long. Young fledge about 30 to 31 days after hatching. The young are cared for by their parents for about a 6 weeks after fledging before setting out on their own. They become sexually mature in their first year, at around nine months old.
Breeding interval: Boreal owls typically breed once yearly. If food is plentiful then multiple clutches may occur.
Breeding season: Breeding season is highly variable, but is typically from the end of February to as late as July.
Range eggs per season: 2 to 7.
Average eggs per season: 5.
Range time to hatching: 25 to 32 days.
Range fledging age: 28 to 36 days.
Range time to independence: 6 to 7 weeks.
Range age at sexual or reproductive maturity (female): 9 to 9 months.
Range age at sexual or reproductive maturity (male): 9 to 9 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Average eggs per season: 5.
Boreal owls provide considerable care for their young, both before and after hatching. Females stay near the nest about a week before egg laying. During this pre-fertilization time, males hunt for themselves and bring food back to their mate. After the clutch has been laid, males continue to provide food for females, but otherwise stay away from the nest. Females incubate the eggs, leaving once daily to eliminate waste. After hatching, males bring food for females and nestlings. Females tear food into smaller pieces that the nestlings can swallow, until they become big enough to eat prey whole. Brooding occurs as long as there is still young in the nest. The final young typically fledges after about 4 weeks from the start of incubation. Once the young have fledged, they stay close to the nest site for about a week, and both parents bring food to them at night, homing in on the begging calls of the fledglings. At the end of the week, the fledglings begin to move farther away, but are still fed for some time by the parents. They finally become independent about six to seven weeks after hatching.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Male, Female); pre-hatching/birth (Provisioning, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Protecting: Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
The boreal owl (Aegolius funereus) or Tengmalm's owl is a small owl in the "true owl" family Strigidae. It is known as the boreal owl in North America and as Tengmalm's owl in Europe after Swedish naturalist Peter Gustaf Tengmalm or, more rarely, Richardson's owl after Sir John Richardson.[3][4]
Due to the boreal owl's shyness and evasive reaction to human activities, nocturnal habits and preferred inaccessible taiga forest habitat, it is rarely seen by humans.
The boreal owl was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae. Linnaeus placed it with all the other owls in the genus Strix and coined the binomial name Strix funerea.[5] The Eurasian scops owl is now placed in the genus Aegolius that was introduced in 1829 by the German naturalist Johann Jakob Kaup with the boreal owl as the type species.[6][7] The genus name is Latin for a screech owl, the word came from the Ancient Greek aigōlios meaning "a bird of ill omen". The specific epithet funereus is Latin meaning "funereal".[8]
Seven subspecies are recognised:[7]
The boreal owl is 22–27 cm (8.7–10.6 in) in length and has a wingspan of 50–62 cm (20–24 in).[9] A female is heavier than a male bird and weighs 131–179 g (4.6–6.3 oz) compared with an average of 107 g (3.8 oz) for a male bird.[10] The plumage is brown above, with white flecking on the shoulders and whitish underparts with rust-colored streaks. The head is large with yellow eyes and a dull white facial disc that is sometimes described as giving the owl a "surprised" expression. The beak is a light yellow, rather than dark like its relative the northern saw-whet owl.[11] The sexes are similar in appearance. The plumage of young birds is chocolate brown. The boreal owl's flight is relatively noiseless and straight.[9]
Its call is similar in sound to the "winnowing" of the North American Wilson's snipe.[12][13]
The boreal owl breeds in dense coniferous forests across northern North America and the Palearctic, and in mountain ranges such as the Alps and the Rockies. This species is not normally migratory, but in some autumns significant numbers move further south. It is rarely any great distance south of its breeding range, although this is partly due to the problems of detecting this nocturnal owl outside the breeding season when it is not calling.
They first breed when one year of age. The nest is usually a hole in a tree often that made by a woodpecker, but the birds also readily use nest-boxes. The clutch is usually 3–7 eggs which are laid at 2-day intervals. They are glossy white and measure 33 mm × 26 mm (1.3 in × 1.0 in) and weigh around 12.5 g (0.44 oz). The eggs are incubated only by the female beginning with the second egg. They hatch asynchronously after 25–32 days. The young are cared for by the female who broods the nestlings for an average of 21 days. The young fledge when aged around 28–33 days and become independent at 5 to 6 weeks.[14]
This small owl eats mainly voles and other mammals (such as mice, chipmunks, other squirrels, gophers, moles, shrews and bats),[15][16] but also birds as well as small amphibians,[17] insects (such as beetles)[18] and other invertebrates. In North America, they have been observed preying on southern red-backed voles, western heather voles, jumping mice, northern pocket gophers and northern flying squirrels.[19] Birds preyed upon include dark-eyed juncos, American robins and common redpolls.[20] It is largely nocturnal, though in the northernmost parts of its range, it has to hunt during daylight because of the very short nights in summer.
Banded boreal owls have been known to live up to 16 years. Due to the owl's small stature it is often eaten by other owls and large raptors thus decreasing its average lifespan.
The boreal owl (Aegolius funereus) or Tengmalm's owl is a small owl in the "true owl" family Strigidae. It is known as the boreal owl in North America and as Tengmalm's owl in Europe after Swedish naturalist Peter Gustaf Tengmalm or, more rarely, Richardson's owl after Sir John Richardson.
Due to the boreal owl's shyness and evasive reaction to human activities, nocturnal habits and preferred inaccessible taiga forest habitat, it is rarely seen by humans.
