BIRD SPECIES AND DISTRIBUTIONS IN YUKON-CHARLEY RIVERS NATIONAL PRESERVE
Northern Hawk Owl (Surnia ulula)
Typically, owls are short-necked, large-headed birds of prey, with hooked bills and razor-sharp talons. All have large, immobile eyes embedded in fluffy, facial disks. Most are nocturnal, hunting only at night. Their silky plumage is almost soundless in flight, an adaptation that enables stealthly stalking of their prey. Both sexes and juvenile birds have similar plumage, though females are larger. Named for its hawk-like profile and flight, the Northern Hawk Owl is the only owl (except for the Pygmy Owl) with a long, banded tail. Their Latin species name, ulula, means "howl or hoot" and refers to their various vocalizations.
Descriptions: Basically non-migratory, Northern Hawk Owls inhabit muskegs, wooded swamps and coniferous-deciduous boreal forests year round. Often perched high atop spruce trees, their hawk-like stature and long, pointed tails are distinctive among owls. Overall, these medium-sized 41cm owls are deep, rich brown but underneath they are heavily barred in tawny and white (which distinguishes them from Boreal and Saw-whet Owls). Their whitish faces are framed in black, with dark markings on the sides of their heads. Speckling on their foreheads and crowns offsets their bright, golden eyes. They fly low, swift and straight, alternating flapping and gliding. Like American Kestrels, Northern Hawk Owls also are known to hover during flight.
Vocalizations: Reminiscent of a Boreal Owl but higher and sharper, the courtship call of the Northern Hawk Owl is heard mainly during the night as a series of popping, whistled notes, "popopopopopopo " The female and juvenile also make a weak, screeching "tshooolP" food-begging call and a thin, rising whistle, "teeee." When alarmed, these owls chirp a series of shrill "qui,qui, qui,qui " notes. During the breeding season in March and April, Northern Hawk Owls were never detected during nightly owl surveys in the Preserve but they were heard calling during the morning when passerine surveys were being conducted.
Nests: Northern Hawk Owls build their platform nests within the excavated cavities of dead trees and snags. They are also known to use the tops of stumps, nest boxes and abandoned basket and platform nests of crows and other birds of prey. Wood chips are molded into the nest cavity to cushion the 3-9, 40 mm, white and unmarked eggs of the clutch. While the female alone incubates the clutch for 25-30 days, the male feeds her from several days before egg-laying through hatching. These owls are fearless and aggressive against nest intruders and will defend their nests vehemently. Young birds hatch asynchronously producing variously sized siblings in the nest. Both parents rear the young birds and fledging (flying) occurs 25-35 days post-hatching. The family group is maintained until the following spring.
Diet: Northern Hawk Owls are primarily crepuscular, hunting in the morning and evening, but may also hunt during the day. Although Northern Hawk Owls predominantly hunt small mammals, including lemmings, mice and shrews, they also consume small birds and insects. Their diet varies seasonally, with small mammals taken primarily during summer and small birds taken in winter. As with all owls, the primary feathers of their wings are modified to eliminate the noise of airflow, creating virtually silent flight for hunting. They hunt by swooping down from the air or their perches and snatching up their victims with their sharp talons. They can also hover and pounce on their prey.
Distribution: Northern Hawk Owls are year-round residents of North America. They span from Interior Alaska eastward across most of central Canada to Newfoundland, Canada. Their summer and winter ranges are virtually identical though irruptions south occur in Alaska during some winters. Within the Preserve, only one Northern Hawk Owl was detected during the Yukon-Charley Rivers National Preserve Bird Inventory (June 1999 and 2000) and it was in the Charley Foothills (CF) ecological unit . However, this may not accurately reflect the density of these owls in the Preserve because of the timing of the survey. Most owls breed and call earlier in spring and the inventory surveys were performed in June. Although they are year-round residents, Northern Hawk Owls are more likely to be seen than heard in the summer.
Detections of Northern Hawk Owl
|Detections of 1 Northern Hawk Owl by detailed ecological unit in Yukon-Charley Rivers National Preserve, Alaska, Avian Inventory, June 1999 and 2000.|