Northern Pygmy Owl
In Canada, three races (Glaucidium gnoma swarthi and
Glaucidium gnoma grinnelli) of Pygmy Owl occur solely within British Columbia, and the third race
(Glaucidium gnoma californicum) occurs in the mountainous interior of British Columbia and southwestern Alberta. Because of the secretive and crepuscular
(most active at dawn and dusk) nature of this species, the natural history and distribution of the Northern Pygmy Owl is poorly known. In Canada, the Northern Pygmy Owl has not been designated by the
Committee on the Status of Endangered Wildlife in Canada
(COSEWIC).
The Northern Pygmy Owl uses a broad spectrum of forest habitat and prefers sites with low to intermediate canopy coverage. The Northern Pygmy Owl is most common near the edges of meadows, lakes and other similar clearings. In the
Rocky Mountains, the Northern Pygmy Owl is usually found in the vicinity of meadows or other sizeable openings in the forest. Human development and habitat alteration appears not to have affected this owl's breeding activity or survival, and partial forest clearing may improve hunting opportunities for the species. In the central and northern Rocky Mountains, the pygmy owl may occur up to elevations of 3600
metres. During the winter months the pygmy owl may be forced to move to lower elevations, including prairie foothills, sometimes well away from forested areas.
In Alberta, the Northern Pygmy Owl is described as preferring dense
stands of coniferous trees broken by small clearings, although mixedwood forests are tolerated provided there is a high proportion of spruce, pine, or fir. Winter records from Alberta suggest that pygmy owls can tolerate almost any habitat, provided there is adequate shelter and food available.
The Northern Pygmy Owl is one of the smallest owls in North America. It has a long, narrow, barred tail, with chestnut to chocolate-coloured
upper parts, streaked breast, and a pair of black patches on the nape that vaguely resemble eyes. The Northern Pygmy Owl has yellow eyes, a yellowish to horn-coloured bill, and yellow feet. As with most owl species in North America, the Northern Pygmy Owl exhibits reversed sexual dimorphism, where the female of the species is larger in size and weight than the male. The Northern Pygmy Owl occurs in both a gray and red colour phase, which is independent of both sex and geographical location. Northern birds are generally larger in size than southern birds, but are indistinguishable by plumage. Tail length also varies geographically with northern races having longer tails than southern races.
The most common territorial call of the Northern Pygmy Owl is a monotonous, repetitive series of hoot notes, given in one to two second intervals. It is also known to complete its advertising call with a series of two to three well-spaced
"kew" or "too" notes.
In Alberta, recorded laying dates include 25 April, 4 May and 7 May. Incubation is believed to be approximately 28 or 29 days in length. Female pygmy owls do not begin incubation until the clutch is complete in order that the young may hatch synchronously. Hatching dates vary from 9 June to 25 August, and brood sizes range from 1 to 7 young. The fledging period is believed to last 29 to 32 days. After fledging, juvenile pygmy owls will remain in the natal territory for an additional 20 to 30 days. Pygmy owls may begin to show signs of sexual maturity at approximately five months of age.
Northern Pygmy Owls are secondary cavity nesters in that they build their nests in tree cavities excavated by woodpeckers or holes created by fungal decay or insects.
The Northern Pygmy Owl consumes a wide variety of prey throughout the year. Mammalian prey accounts for around 60.8% of the diet (based on
biomass), and birds account for 36.6%. Although rodents appear to be the dominant prey item during the breeding season, pygmy owls are highly opportunistic and will take almost any prey. A Northern Pygmy Owl was observed catching and killing a red squirrel, and even taking a woodpecker nestling from inside a tree cavity. Pygmy owls have been observed feeding on Boreal Toads (Bufo
boreas) and Columbia Spotted Frogs (Rana luteiventris) in the Canmore and Kananaskis areas.
Given the small size and crepuscular nature of the Northern Pygmy Owl, the species has many potential predators and competitors. The presence of larger, aggressive corvids (ravens, magpies, jays) ay inhibit the hunting behaviour of the Northern Pygmy Owl.
Diurnal birds of prey such as Cooper's Hawk, Sharp-shinned Hawk,
Northern Goshawk, Broad-winged Hawk, and Red-tailed Hawk are most likely the dominant predators of the Northern Pygmy Owl. Other forest owls in Alberta are predominantly nocturnal and are probably not important predators or competitors of the Northern Pygmy Owl. However, the Northern Saw-whet Owl
and Northern Hawk Owl have been known to actively hunt during the day, and predation of a Northern Pygmy Owl by a Saw-whet owl has been documented. Given the pygmy owl's habit of nesting in cavities, mammalian predators are likely few. However, red squirrels and pine martens
may be responsible for some mortality during the nesting season when inexperienced young or incubating adults are more susceptible to predation.