Aegolius acacias (Aegolius: Greek, “A kind of owl;” acadicus: for Nova Scotia, where first specimen was found).
Two recognized; only one subspecies in continental North America (A.a.acadicus); the other (A.a.brooksi) is endemic to the Queen Charlotte Islands off British Columbia.
SW Alaska and central Canada, south through US and central Mexico.
Prefers conifer forests near swampy area, but will also accept moist, mixed, mature woods. In winter, it favors thick evergreen stands or dense brushy tangles in parks, estates, and even yards, although can sometimes be found in an isolated evergreen. When roosting, this owl can be closely approached, and even handled.
Diet consists of small woodland mammals (mice, voles, shrews, chipmunks, baby squirrels, and bats), small songbirds (especially in spring), and insects. The largest prey known to have been taken by these tiny owls are doves and flying squirrels. The Saw-whet hunts nocturnally, most active at dusk and just before dawn, catching most of its prey on the ground after a short flight from an elevated perch. It also catches some insects on the wing.
March to July (usually April and May). Solitary. Because of the migratory (or wandering) tendencies of the Saw-whet, it probably does not form long term pair bonding. Predominately uses abandoned woodpecker cavities, mostly those of flickers, 14 – 60 feet above the ground; sometimes nests in natural tree holes. Will accept birdhouses. No materials added to the nesting cavity, except possibly a few feathers. Clutch is 4 – 7 eggs, usually 5 – 6.
In mountainous regions of the west, minor vertical movements to lower areas during winter. The northern populations of central and eastern US migrate south to Texas and the Gulf States; the most mobile are the immatures. Eruptive migrations also occur when food supply is short. Spring movement is from March through May, while fall migration extends from September to the end of November.
Stable … so far. However, necessary dense evergreen forests throughout their east coast wintering grounds are being threatened by pending industrial projects, so their future there will depend upon the success (or not) of the many local conservation groups desperately acting in their behalf. Besides possible habitat loss, these retiring and gentle owls, throughout their entire range, also are gradually being forced out of their breeding and wintering territories by the more aggressive, and numerous, screech owls.