Boreal Owl

Boreal Owl (Aegolius funereus)

The Boreal, or Tengmalm’s Owl is a small owl with a large, rounded head and no ear-tufts. The species name funereus comes from the Latin word for funeral. In North America, where it is known as the Boreal Owl. In other parts of the world, it is known as Tengmalm’s Owl. Other names for this Owl are Richardson’s Owl, Sparrow Owl, Partridge-haw and Pearl Owl. The facial disc is whitish, surrounded by a dark rim with small white spots, which makes them look very similar to the larger Northern hawk Owl. There is a small dark portion between the eyes and the base of the bill. Eyes are pale to bright yellow. Upper parts are dark brown with bold white spotting. Their chest and belly are off-white, with broad streaks of darkish brown, denser on the breast and trailing off at the lower belly. The tail is short and brown, with 4-5 white cross-bars. The legs and feet are covered with white feathers. Claws are darkish to blackish brown, and have very sharp blackish tips.

They have a body length of 8-11 inches, wingspan of 21-24 inches and a body weight of 3.3 – 7.6 ounces.

Lives in boreal forests with spruce, aspen, poplar, birch, and balsam fir. In mountains of West, found in subalpine forests of fir and spruce. Hunting habitat includes forest meadows and open forests. When roosting they need dense conifers where they roost 5-6m up.

(Note: Boreal Owls are nocturnal hunters so they are often found roosting in the daytime. This allows for some great Boreal Owl pictures. However, when taking your Boreal Owl photographs keep your disturbances to a minimum and don’t remove any branches in front of the owl. These branches are camouflage for the owls from larger raptors that may kill the owl for food.)

Boreal Owls are nocturnal ambush predators. This means that they will sit on a branch waiting for prey as opposed to some owls that glide over fields scanning for prey. While the eyes of Boreal Owls are exceptional in low light it is actually their amazing hearing that they use to find prey. The ears of the Boreal owl are found close to their eyes on the edge of their facial disc. This facial disc acts like a parabolic collector that channel the sound to the ears. Their ears are not directly across from each other but are slightly diagonal to each other, one being higher and one being lower. This adaptation gives most owls 3 dimensional hearing and makes locating prey easier. You will often see an owl turn its head to one side. This helps use that 3d hearing to narrow down the prey’s location. It also makes a comical owl photograph.

Boreal Owls are primarily rodent hunters, especially voles. But they will also lemmings, mice, shrew and moles. But they will also take small birds, bats, squirrels, frogs and beetles.

They usually nest in old woodpecker holes, but will also use nesting boxes. They do not add nesting material. Males begin searching for nest holes in late Winter. Prey items are often deposited into the hole, after which, the male will sing from a perch. If an interested female approaches, the male will fly to the cavity and utters a stuttering or trilling song. The female may then inspect the nest hole, and if she accepts it, will stay. The male brings her food while she is in the hole.

Several days later, the female lays 3-8 white eggs which are laid a day apart. Incubation begins with the first or second egg laid, and lasts 28-29 days. The female does all incubation and the male brings food to the nest. The chicks hatch a day apart, and their eyes open after 10 days. They leave the nest at about 30-32 days, and are looked after by the parents for 4-6 weeks. They are mature at about 9 months.

The Boreal Owl is usually single-brooded, but will sometimes try to produce 2 broods. Breeding success is fairly high. Desertion or predation of eggs and young are the primary causes of nest failure. Unlike many other owls, pair bonding is only seasonal.

References: Cornell Labs of Ornithology, The Owl Pages