The Tengmalm’s Owl, Aegolius funereus, is also known as the Boreal Owl in North America.
It is named after the Swedish naturalist Peter Gustaf Tengmalm.
Distribution / Range
This bird occurs in most of North America (including northern Canada), Europe and Asia. In the US, they are found in the Rocky Mountains down to New Mexico. They generally inhabit old-growth forests.
This species is not normally migratory, but in some autumns many of them may move further south.
Its global population is estimated to consist of about 220,000 individuals.
The Tengmalm’s Owl is a small owl averaging 22-27 cm in length, with a 50-62 cm wingspan.
The plumage is brown above, with white flecking on the shoulders. It is whitish streaked brown on the underside.
It has a large head, with a white facial disc, and yellow-orange eyes.
Immature birds have a chocolate brown plumage.
Their flight is strong and direct.
Breeding / Nesting
They are traditionally considered “monogamous” – however, European studies reported that a male may mate with up to three females, and that the females themselves may pair up with two different males.
They found that this happens most often when there are large numbers of mice around to feed on.
The average clutch size consists of 3 – 6 eggs. They typically nest in abandoned woodpecker nests.
Feeding / Diet
This owl eats mostly voles and other mammals. It may also take birds, insects and other invertebrates.
This species is typically nocturnal (active at night), but though in the northern most parts of its range, it may hunt during daylight hours due to the very short summer nights.
Calls / Vocalizations
Its call sounds like a rapid sequence of “ting, ting, ting, ting“.