Northern Saw-whet Owls

Did you know????

Northern Saw-whet Owl

Aegolius acadicus

· We are part of Project Owlnet, a group of cooperating Saw-whet Owl banding stations in the United States and Canada. Stations are located throughout the Great Lakes, New England and the mid-Atlantic. The project mission is to promote standardized banding efforts as a tool for monitoring owl population trends and migration patterns, contributing to the conservation of owls and their habitats.

· The Saw-whet Owl is the smallest owl found in the eastern United States. It is only 7-8 inches from bill to tail. Its wingspan of 18-22 inches makes it appear larger in flight. Its small size allows banders to capture it with the same mist net techniques used for passerines.

· Female owls are generally heavier and have longer wings than males. Taking both of these measures into consideration allows banders to determine the sex of a Saw-whet Owl. Wing chord: males 125-142mm, females 129-147mm. Weight: males 70-88g , females 85-130g

· The Saw-whet Owl does not replace all of the flight feathers on the wing every year. Banders look for contrasts in wing feather color and wear to determine an owl’s age.

· Saw-whet Owls have heavily feathered legs and feet. The bander needs to be careful to use the right size band and to feel both legs to verify that the owl is not already banded.

· The Saw-whet’s primary courtship call is a monotonous series of single, whistled “toot” notes, which may last for several hours without a break. This call is given by the male only and is restricted to breeding season (March - May). The audio lure used by banders is a playback of this call.

· The Saw-whet’s name comes from its "skiew" alarm call, which is said to resemble the whetting of a saw. We often hear this call when an owl is in the vicinity of our nets.

· Defensive behaviors of Saw-whet Owls include bill snapping and raising and extending the wing closest to the disturbance. Some of the owls we band exhibit these behaviors, otherwise they are extremely passive.

· The Bird Banding Laboratory lists the longevity record for a wild Saw-whet Owl at 10 years, 4 months.

· The Saw-whet Owl’s main breeding territory includes southern Canada, the western United States, the Great Lakes region, New England and locations in the Appalachians. They breed in coniferous forests & mixed woodlands. They winter throughout much of their breeding range, but the northern and eastern populations are highly migratory, regularly moving to the central United States through Georgia. They winter in habitats with dense cover, especially conifer groves.

· In the eastern U.S., Saw-whet Owl spring migration falls between March 1 and May 31 and fall migration extends from September 1 to November 30. It is thought that the owls follow two main migratory corridors: the Ohio River valley and the Atlantic coastline. Juveniles are more likely to migrate than adults and tend to move further south. They utilize habitats along their migration routes that are similar to their breeding habitats. Collective banding experience has shown that the best migratory flight nights are clear nights with light westerly winds after the passage of a cold front.

· Saw-whet Owls are nocturnal, hunting mainly at dusk and dawn. They generally hunt by remaining motionless on a low perch and dropping down on prey, which they locate by both sound and sight. They roost in dense conifers during the day relying on the foliage cover and their plumage for camouflage.

· Saw-whet Owls feed primarily on small rodents such as mice, shrews and voles. Other prey includes squirrels, moles, small birds, frogs and large insects. When prey is plentiful, they will cache excess food. Saw-whet Owls are preyed upon by larger owls such as Great-horned and Barred, and hawks such as the Cooper's Hawk and the Northern Goshawk.

References

Johnsgard, Paul A. 1988. North American Owls: Biology and Natural History. Smithsonian Institution, Washington, DC.

Kaufman, Kenn. 1996. Lives of North American Birds. Houghton Mifflin Company, New York, NY.

Klimkiewicz, M. K. 2002. Longevity Records of North American Birds. Version 2002.1. Patuxent Wildlife Research Center. Bird Banding Laboratory. Laurel MD.