The Saw-whet Owl (Aegolius acadicus) is a small owl.

Adults are 18cm long with a 43 cm wingspan. They have a large round light grey face with brown streaks, a dark bill and yellow eyes. The underparts are pale with dark streaks; the upper parts are brown with white spots.

Their breeding habitat is coniferous forests, sometimes mixed or deciduous woods, across North America. They nest in a tree cavity, usually one created by a woodpecker. They will sometimes use nesting boxes.

Some are permanent residents; others may migrate south in winter or move down from higher elevations.

These birds wait on a low perch at night and swoop down on prey. They mainly eat small rodents; on the Pacific coast, they may also eat crustaceans and aquatic insects. Like many owls, these birds have excellent hearing and exceptional vision in low light.

This bird was named for its call, which is said to resemble a saw being sharpened with a whetstone. It is fairly common, but not always easy to spot.