Whiskered Screech-Owl Biology

A Reference for North and Central American Owls

Name: Whiskered Screech-Owl – Megascops (Otus) trichopsis
Other Common Names: Arizona Whiskered Owl; Spotted Screech-Owl; Whiskered Owl.

Subspecies: There are three accepted races of Whiskered Screech-Owl in North and Central America. Only one of these races has a range crossing into North America. Six additional races are described but not yet recognized and subsequently included within the following.
M. t. aspersus is found from S. E. Arizona and S. W. New Mexico to Sonora and Chihuahua, Mexico.
M. t. trichopsis is found in the highlands of central Mexico from Michoacan to Veracruz, Oaxaca and Chiapas. The described races ridgwayi (Michoacan), guerrerensis (S. W. Mexico), and pinosus (Veracruz) are included.
M. t. mesamericanus is found from S. E. Mexico (Chiapas) to N. C. Nicaragua. The described race pumilus (Honduras) is included.

Measurements and Weights:
Wingspan: 16 – 20 in.
Length: 6.5 – 8 in.
Tail: 2.5 – 3 in.
Average Weight: Male: 3 oz.
Average Weight: Female: 3.3 oz.

Description: The smallest of the three Screech-Owls that occur in North America. All three Screech-Owls are very similar in appearance and can only positively be distinguished in the field by their call (see the Western Screech-Owl biology for the visual differences of all three owls). The Eastern and Whiskered Screech-Owls have no overlap in range in North America so confusing these is not possible. The ear tufts are conspicuous when raised. Its facial “whiskers” give rise to the owl’s name. These bristles are more numerous and longer (extending well beyond the bill) than in the other Screech-Owls. The owl is generally brownish-gray above with dark brown and white mottling, short streaks or spots. Under parts are dull white with dark brownish-gray streaks and crossbars. The iris is lemon-yellow and the bill is yellow to grayish or greenish-yellow.

Young: Initially pure white. This plumage is replaced with a dull grayish-brown coat above with indistinct gray and white barring or mottling. Under parts are dull white, broadly barred with grayish-brown.

Habitat:

In general the Whiskered Screech-Owl is found at higher elevations than the Western Screech. Although it is resident down into the Pine / Oak zone of the Montane habitat and the Western Screech will inhabit this zone in areas where the Whiskered Screech is not present, they seem to remain ecologically isolated. The two owls do not seem to intermingle in habitat and there seems to be a clear division between the two owls as you rise in elevation. The Whiskered Screech inhabits up into the pine zone of the Montane habitat where it will come in contact with the Flammulated Owl and down into the upper Sonoran zone where there is a significant overlap with the Elf Owl.

Food and Feeding:

The primary foods of the Whiskered Screech are insects with only a single record of a vertebrate (mouse) found in the stomach content of an owl. The insects of choice are usually flying although centipedes seem to be an important winter food. Also taken are moths, beetles, spiders, and grasshoppers. Usually hunts from a perch in a tree where it will fly out to catch winged prey although may also fly back and forth in tops of trees catching multiple insects.

Breeding:

There is very little information known of the breeding of this owl. Clutch size seems to average 3 to 4 eggs. The nests have always been located in natural cavities or woodpecker holes. Fewer nests have been found than any other North American Owl. There is no information on incubation or fledging periods although likely to be the same as Eastern and Western Screech-Owls. Egg laying is in April and May.

Movements and Life Span:

The Whiskered Screech-Owl is believed to be entirely sedentary. Most of the population is far enough south that it is unaffected by winter weather. In the north of its range (Arizona) there may be some downslope movements in winter.