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Northern Hawk Owl - Surnia ulula

More Northern Hawk Owl (Surnia ulula) Photos >>
 
Calls - Surnia ulula
Typical call Floatplane Lake, Alaska, USA. July 1999. CC Dan Lane
Scream Northern Minnesota, USA. Call given at perch after unsuccessful hunting attempt. © Richard Peet
Tremolo Northern Minnesota, USA. Given in response to above 'scream' call. © Richard Peet

Introduction: The Northern Hawk Owl is a medium sized Owl with no ear-tufts, a whitish face and long pointed wings. Local names for this bird include Day Owl, and Hudsonian Owl.

[For help with terms used in the description, see parts of an owl. For general characteristics common to most owl species, see owl physiology.]

Description: The facial disc is whitish, broadly rimmed blackish at the sides. Eyebrows are white, and eyes are pale yellow (golden yellow in juvenile). The bill is pale yellowish-green and the cere pale greyish-brown. Upperparts are dark grey to dusky greyish-brown, with the crown densely spotted whitish and the nape with indistinct false eyes. Mantle and back are dusky grey with some whitish dots. Scapulars are mainly white, forming rather broad white bands across shoulder. Flight feathers are dark grey-brown with rows of white spots. the Tail is long and graduated and dark greyish-brown with several narrow whitish bars. Underparts are whitish, barred with Greyish-brown. Legs and toes are feathered. The soles of the toes are dirty yellow, and claws are dark brown with blackish tips.

Size: Length 36-41cm. Wing length 218-258mm. Tail length 160-204mm. Weight males 215-375g, females 323-392g.

Habits: A largely diurnal bird. Flight is straight with rapid wingbeats and open-winged glides; often hovering, perching in exposed sites such as a treetop or post. Flicks tail when excited. Not social - seen mostly singly or in pairs.

Voice: Typical male call is a rapid, melodious, purring trill of up to 14 seconds long, which consists of about 11 to 15 notes per second. It begins softly, rises slightly in pitch and increases to a vibrating trill before breaking off abruptly. This is repeated at various intervals. Females utter a similar, higher-pitched, less clear song. Both sexes give a piercing kiiiiirrl or a kestrel-like kwikikikikkik call when excited. Screeching calls are also uttered. A soft uhg or uih is given as contact between pairs. Young beg with a drawn-out chchchiep.

Hunting & Food: Takes mainly small mammals as prey, mostly lemmings and voles. Will also take birds, frogs and occasionally fish. Prey weight is normally below 70g. Hunts by searching from a lookout, then quickly flying to swoop down on prey. Has been observed hovering also.

Breeding: Male advertises potential nest sites, and the female selects one. Nests in Cavities on top of broken trunks, natural tree hollows, abandoned holes of large woodpeckers. Will accept nest boxes, and occasionally use a stick nest of a larger bird. Laying normally occurs in April and the first half of May. Clutch sizes are usually between 5 and 13 eggs, each 36-44  x 29-34.4mm. Eggs are laid at 1-2 day intervals, and incubated by the female alone for 25-30 days. During this time, the male feeds the female. After hatching, the chicks are brooded for 13-18 days, and leave the nest at 23-30 days, and can fly well by the time they are about 5-6 weeks old. They become independent of their parent's care towards the end of August. They become sexually mature towards the end of their first year. Pairs are monogamous during breeding season.

Habitat: Open boreal coniferous forest with clearings and moors in lowlands or mountains. Hunts in semi-open country with scattered trees or groups of trees.

Distribution: Eurasia from Norway, Sweden and Finland east through Siberia to Kamchatka, Sakhalin, and North China, in Central Asia south to Tien Shan. North America from Alaska east to Labrador.
Moves widely within its area of distribution, breeding where food is abundant. In some Autumns, invasions (mainly juveniles) occur in areas south of its normal range.

Distribution of Northern Hawk Owl - Surnia ulula
Distribution of the Northern Hawk Owl Surnia ulula

Status: Not threatened or endangered.

Original Description: Linnaeus, Carolis. 1758. Systema Naturae ed. 10, p. 93.

Subspecies: S. u. ulula, S. u. caparoch, S. u. tianschanica

References:

Boyer and Hume. 1991. "Owls of the World". BookSales Inc
Campbell, Wayne. 1994. "Know Your Owls". Axia Wildlife
del Hoyo, Elliott & Sargatal. 1999. "Handbook of the Birds of the World: Barn Owls to Hummingbirds". Buteo Books
Duncan, James R. 2003. "Owls of the World: Their Lives, Behavior and Survival". Firefly Books
Johnsgard, Paul A. 2002. "North American Owls: Biology and Natural History". Smithsonian
König, Claus & Weick, Friedhelm. 2008. "Owls: A Guide to the Owls of the World (Second Edition)". Yale University Press
König, Weick and Becking. 1999. "Owls: A Guide to the Owls of the World". Yale University Press
Mikkola, Heimo. 2012. "Owls of the World: A Photographic Guide". Bloomsbury
Voous, Karel H. 1988. "Owls of the Northern Hemisphere". The MIT Press

Page Information:

Page compiled by . Page last updated 2013-07-27

OwlPages.com Owl Species ID: 180.010.000

 
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