Although their range does include SḴŦAḴ | Mayne Island, you may never have seen a Western screech owl. There are likely a few reasons for that:

• They are small owls that stand only about 20 cm high, and are so well camouflaged they can elude even experienced birders. When roosting, a screech-owl that senses danger will often stand up tall, partially close its yellow eyes, and remain silent and motionless. Mottled brownish or grayish feathers and short “ear” tufts help them blend seamlessly into surrounding tree bark and leaves.
• Unlike the more common barred owl, which can often be spotted roosting in the open during daylight, they are seldom vocal or active during the day, and often take shelter in tree cavities or dense stands of trees until sundown.
• Their numbers have been decreasing over the past 30 years in our area.

A roosting screech owl. Photo by Holly Keepers, US Fish and Wildlife Service.

Taxonomy

Like many other birds, the scientific classification of the screech owl has changed a lot over the years, as battles waged between taxonomy “splitters” and “lumpers,” and DNA analysis brought new evidence to light. Currently, two species are recognized in Canada: the Western screech owl (scientific name Megascops kennicottii ) and the Eastern screech owl (Megascops ascio). Within the Western screech owl, as many as 18 subspecies were proposed at one time, but currently there are just two subspecies recognized in Canada: M. k. macfarlanei in the southern interior of B.C., and M. k. kennicottii on the coast, including the Southern Gulf Islands.

Habitat and Diet

On our coast, western screech owls are found in a variety of low altitude forests, but their favourite habitat is a mix of deciduous and coniferous trees near streams; their presence is an indicator of a healthy riparian woodland environment. They can also be found in treed urban and suburban environments.

Large trees (usually more than 25 cm in diameter) are required to provide a suitable hollow for nesting and roosting. Often screech owls will use holes originally excavated by flickers or pileated woodpeckers. Two hollows per territory are ideal: one for the female and young, and another for the male. If the owls cannot find suitable natural cavities intrees, man-made nest boxes are readily accepted.

The Western screech owl preys on small animals, including mice, shrews, birds, frogs, salamanders, small fish, a range of insects, and even worms and slugs.

Nesting

The female screech owl is larger than the male, as in most raptors. While it is unclear why, one theory is that since the female usually sits on the nest, larger females are more able to defend the eggs and young from predators.

Once a nest site in a tree cavity or nest box is chosen, the female lays two to six eggs in the bottom of the cavity (without building an actual nest) and incubates them for about 26 days while the male brings her food. After the eggs hatch, the female continues to brood and feed the owlets. The male is tasked with providing food to the female and owlets until they develop feathers and no longer need brooding. Both parents then work hard to hunt and feed the young owls. About a month after hatching, they leave the nest. Fledglings are cared for by their parents for another five to six weeks before dispersing in late summer.

The Western screech owl is non-migratory; a pair will defend its territory year-round.

A Downward Population Trend

Unfortunately, the population of our local screech owl subspecies, M. k. kennicottii, has shown a strong decline since the 1990’s, and has nearly disappeared from the southern part of its range in metro Vancouver, Victoria, and the Gulf Islands. The kennicottii subspecies is listed as a species of Special Concern (one at risk of becoming threatened or endangered) by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and by the B.C. Provincial government.

Western screech owl. Photo by Dominic Sherony, used under Creative Commons License.

---

Local bird expert and Conservancy Executive Director, Michael Dunn, has surveyed owls on Mayne for the past ten years and has seen the number of Western screech owls fall from three or more in initial surveys to none or just one more recently. He thinks there may be only one screech owl territory currently occupied on the island. Studies have pointed to several possible reasons for population decline in this subspecies:

• In the Lower Mainland and Southern Vancouver Island, the habitat preferred by Western screech owls (low elevation forests near water) is also the type of area cleared for urban and agricultural development. Without trees for nesting and roosting, the population of owls declines.
• Ongoing logging removes mature trees, as well as dead trees and snags, which serve as nest sites and roosts.
• In suburban areas, competition with introduced grey squirrels for nest cavities, and predation by squirrels on owlets.
• Screech owls face predation from newly established populations of the larger Barred owl, whose range has expanded dramatically over the past century.

Originally found in the eastern U.S., barred owl range has expanded to most forests in Northern and Central North America, including B.C. Barred owls are now quite common on SḴŦAḴ | Mayne Island, and you may have heard their “Who cooks for you?” call at night. Michael Dunn has detected an increase in barred owls on Mayne in his surveys.

This rapid expansion of barred owl territory could have been a natural range expansion, human caused, or a combination of both. One theory is that the barred owl’s westward movement was precipitated by dramatic changes to the boreal forest and Great Plains as growing European settlement altered the landscape.

What You Can Do

Competition from barred owls may be the primary cause for the decline of the Western screech owl. This factor is difficult for landholders to mitigate, but there are some steps that you can take to help compensate for habitat loss:

• Leave large trees and dead snags standing on your property if possible, to provide nesting sites.
• Erect nest boxes in suitable areas. Plans and instructions are available from Audubon.org or from Nestwatch.org.
• If you see or hear a Western screech owl on Mayne, please report your sighting to Michael Dunn at ed@mayneconservancy.ca.

References & Further Reading

Here are the sources for the article; they also make interesting reading:

• Atlas of Breeding Birds of British Columbia, Species Account, Western Screech Owl
• BC Conservation Data Centre: Conservation Status Report Megascops kennicottii kennicottii, Western Screech-Owl, kennicottii subspecies
• COSEWIC Assessment and Status Report on the Western Screech-Owl kennicottii subspecies Megascops kennicottii kennicottii and the Western Screech-Owl macfarlanei subspecies Megascops kennicottii macfarlanei in Canada – Committee on the Status of Endangered Wildlife in Canada, 2012
• Elliott, K. Declining numbers of Western Screech Owl in the Lower Mainland of British Columbia. British Columbia Birds Volume 14, 2006
• South Coast Conservation Program – species profile
• U.S. Fish and Wildlife Service: Invasive species management-Barred Owl Management