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  ScienceZoologyBirdsOrder Strigiformes
 
Northern Saw-Whet OwlSaw-Whet Owl

Aegolius acadicus

Description

One of the smallest owls, the saw-whet is 7 to 8 inches long, has a wing span of 17 to 19 inches, and weighs up to 5.5 ounces. It has no ear tufts, but does have a prominent facial disk. The face is outlined in brown and white, with the white forming a distinct "V" shape from the base of the black bill up and over the eyes. The underparts are white streaked with brown. Both sexes are similar in plumage, but the female is larger than the male. Juveniles lack white markings on the back, except for small amounts on the wings and tail.

Distribution and Habitat

distribution of the northern saw-whet owl (breeding range in green)The saw-whet owl breeds across all of southern Canada and throughout the Great Lakes region, and from southern Alaska through the western states into central Mexico. Winter populations can be found throughout most of North America. Populations in the northern and eastern portions of the range are far more migratory than in the western and southern portions, and juveniles are more likely to migrate than adults.

Saw-whets live in a variety of forested habitats, but prefer riparian regions for breeding and areas with dense cover for roosting. They are only found in urban areas during migration. Although most common at higher altitudes, they can be found down to 1,000 feet above sea level.

Diet

Mice make up the majority of the saw-whet's diet, but other small rodents are taken as well. Saw-whets will also take the occasional bird, as well as insects and spiders. As are most owls, the saw-whet is capable of taking prey as large as itself, and has been known to prey on small flying squirrels, rock doves, and other similarly sized animals.

Although it hunts almost exclusively at night and, therefore, has the excellent night vision characteristic of owls, the saw-whet relies more on hearing than on sight when hunting. An opportunistic hunter, it generally waits on a tree branch or other suitable perch and listens for the right movement; once prey has been located it will then use its vision to zero in on its meal and grab it with its strong feet and sharp talons.

It is not uncommon for a single saw-whet to take more prey in one night than it can consume. Excess prey is often cached for later consumption, allowing it to "store up" for lean times.

Reproduction

Although saw-whets are generally monogamous, pairs usually only stay together for one breeding season, which runs from March through July. The male typically picks the nest site, which is almost always an abandoned woodpecker hole, and then attracts the female by singing.

Four to seven eggs are laid per clutch, and are incubated exclusively by the female for 27 to 29 days. Although he takes no part in incubating the eggs, the male does bring food for the female, as well as for the newly-hatched chicks. He will continue to bring food for the chicks for up to a month after hatching. Chicks fledge at 4 to 5 weeks, and are fully independent at 10 to 13 weeks. It is believed that saw-whets are sexually mature by the end of their first year.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Aves
order Strigiformes
family Strigidae
genus & species Aegolius acadicus


All About Birds www.allaboutbirds.org/guide/Northern_Saw-whet_Owl/id
Owling www.owling.com/Saw-whet_nh.htm

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  The Robinson Library > Science > Zoology > Birds > Order Strigiformes

This page was last updated on February 02, 2015.

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