- 7.5–9.8 in
- 21.7–24.4 in
- 3.5–10.8 oz
- Petit-duc des montagnes (French)
- Tecolote occidental (Spanish)
- Oddly enough, the Western Screech-Owl doesn't really screech; it makes an accelerating series of hollow toots. The “screech” part of its name better suits the closely related Eastern Screech-Owl, whose primary sound is a descending whinny.
- The diminutive Western Screech-Owl is a predator to be reckoned with: it occasionally takes prey bigger than its own body, including cottontail rabbits. At other times they’ve been seen eating bats, insects and earthworms, which they collect from rainy roads and even compost piles.
- Western Screech-Owls sometimes perch at the entrance of their roost holes during the day, but they remain nearly invisible by pressing their head and body feathers against the tree to blend in.
- A pair of captive Western Screech-Owls lived to be 19 years old. The longest lifespan recorded in the wild is at least 13 years: a bird banded in Claremont, California, in 1926 and recovered there in 1939.
Western Screech-Owls live mainly in forested habitats, especially in bands of deciduous trees along canyons and other drainages. Common trees include cottonwood, aspen, alder, water birch, oak, and bigleaf maple. But you can also find Western Screech-Owls in suburbs, parks, deserts, coastal areas, and in mountains up to about 6,000 feet elevation.
Western Screech-Owls are carnivores. They eat mostly small mammals, thought they also eat birds, fish, amphibians, and invertebrates. Their diet can vary tremendously from place to place and from season to season. Mammal prey includes pocket mice, deermice, grasshopper mice, shrews, woodrats, kangaroo rats, as well as bats and occasionally rabbits. Invertebrate prey include insects, crayfish, worms, slugs, snails, and whip scorpions. They are sit-and-wait predators, perching inconspicuously on tree branches and watching the ground for prey. These owls sometimes perch above creeks, watching for crayfish to emerge from the shallows. They also glean invertebrates from foliage and catch flying insects in midair, or bats leaving a roost.
- Clutch Size
- 2–7 eggs
- Number of Broods
- 1 broods
- Egg Length
- 1.3–1.7 in
- Egg Width
- 1.1–1.4 in
- Incubation Period
- 26–34 days
- Nestling Period
- 35 days
- Egg Description
- Condition at Hatching
- Covered in white down; eyes closed.
The Western Screech-Owl does not build a nest, but lays its eggs on whatever material happens to be in the cavity. Western Screech-Owl nest cavities are about 1 foot in diameter and 1 to 1.5 feet deep. Entrances are just big enough to admit an owl's body; presumably this helps prevent larger predators from getting in. Western Screech-Owls sometimes take over the nests of other species.
Like many small owls, Western Screech-Owls nest in tree cavities excavated by woodpeckers. They may also use naturally occurring cavities, such as those formed where branches have broken off a trunk. Very occasionally, they nest in cavities in cliffs and banks. They sometimes use nest boxes. Wherever the location, the male owl finds a suitable hole, then calls or leads the female to it, sometimes by carrying an enticing prey item. They may use the same cavity for several years in a row.
Western Screech-Owls are nocturnal. They usually leave their roosts around sunset to forage, returning within a half-hour of sunrise. You may glimpse them perching at the entrances of their roost cavities on sunny winter days. They are "socially monogamous," meaning that pairs raise young together, although both sexes may also mate outside the pair. The male and female in a pair often preen each other. During courtship and mating, they sing duets, and the male presents food to the female. In breeding season, the male roosts near the nest cavity. During the last weeks of the nestling period, the female also leaves the nest, often roosting close enough to the male that their bodies touch. Both adults guard the entrance from crows, jays, and other predators. The male provides almost all the food for the female and young during nesting, while the female incubates eggs and broods the baby owls. She stays with her young constantly for the first 3 weeks, then takes increasingly long breaks to help the male hunt. Owlets leave the nest before they can fly well. They remain with their parents for about 5 weeks after leaving the nest site.
Western Screech-Owl population trends are difficult to study because of the birds' nocturnal habits. The North American Breeding Bird Survey reports that its sample sizes are not large enough to adequately estimate population changes in this species, but populations appear to have declined between 1966 and 2014. Partners in Flight estimates the global breeding population at 400,000, with 69% of these in the U.S., 6% in Canada, and 25% in Mexico. They rate a 12 out of 20 on the Continental Concern Score. The Pacific Northwest population of Western Screech-Owls has proven vulnerable to predation from recently arrived Barred Owls, and is on the 2014 State of the Birds Watch List, which lists bird species that are at risk of becoming threatened or endangered without conservation action. The streamside vegetation where Western Screech-Owls thrive tends to be prime real estate for humans as well. High-density development and clearcut forestry have a negative impact on screech-owl habitat. They are also dependent on standing dead trees containing cavities for their nest sites. Maintaining robust populations of the Western Screech-Owl will require protecting open forested areas along bodies of water in both rural and residential areas. Conservation efforts benefit from Western Screech-Owls' abilities to tolerate human presence and adapt to nest boxes.
- Cannings, R.J. and T. Angell. 2001. Western Screech-Owl (Megascops kennicottii), In The Birds of North America Online, No. 597 (A. Poole, Ed.), Cornell Lab of Ornithology, Ithaca, New York.
- North American Bird Conservation Initiative, U.S. Committee. 2014. State of the Birds 2014 Report. U.S. Department of Interior, Washington, DC.
- Partners in Flight. 2012. Species assessment database.
- Sibley, D.A. 2014. The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York.
- USGS Patuxent Wildlife Research Center. 2015. Longevity records of North American Birds.
USGS Patuxent Wildlife Research Center. 2014. North American Breeding Bird Survey 1966–2014 Analysis