As the days become shorter with winter's approach, opportunities to see owls increase. For one thing, with more hours of darkness you don't have to lose sleep to get acquainted with these birds. What's more, you may encounter certain owls that normally live outside your region. Species like the northern hawk owl and snowy owl periodically "invade" southern Canada and the northern U.S. in winter, when a shortage of prey drives them from their usual haunts in large numbers.

Snowy and northern hawk owls are among the least nocturnal of their kind, often hunting or sitting in the open during the day. Look for snowy owls in treeless habitats that resemble the Arctic tundra where they nest: farm fields, grasslands, marshes, beaches and airports. They usually perch on the ground, less frequently on fence posts, utility poles or buildings. Northern hawk owls are generally boreal forest-dwellers, but they sometimes visit open woodlands and prairies when they come south in winter. These bold owls, which show little fear of humans, commonly sit in plain view on exposed tree tops.

Most other owls prefer to operate under cover of darkness. Prime owling times are at dusk and dawn, extending about an hour on either side of sunset and sunrise. As the evening light fades, owls leave their roosts and begin hunting for their breakfast. Once their immediate hunger is satisfied, they are less active, but as daybreak approaches the urgency to refuel returns.

Many owls hunt from perches along the edges of fields, meadows or wetlands, listening and watching intently for scurrying rodents or other prey, then swooping down on the unsuspecting victim. The silhouette of a perched owl is distinctive. Note the upright posture and large, round head with no visible neck. Even in low light, it is often possible to identify the species based on body size and the presence or absence of ear tufts-which are actually erect feathers, not ears. Great horned owls, for example, are hefty birds with prominent ear tufts. Great gray owls are slightly larger, but slimmer and tuftless.

While the bare branches of deciduous trees in winter facilitate twilight owl-spotting, eyesight alone isn't always enough to figure out who's who. Learning the signature calls of the owls most likely to frequent your neighbourhood will make your owl prowls much more satisfying. One of the easiest to recognize is the barred owl's rhythmic sequence of loud hoots, which asks the question, who-cooks-for-you, who-cooks-for-you-all? Equally memorable is the northern saw-whet owl's monotonous repetition of short whistled notes, a sound that reminds many listeners of saw teeth being filed.

Great horned owls begin nesting as early as January and often start staking out territories and seeking mates in late fall or early winter. Many rural residents will recognize their mellow, deep-toned hoots, which carry far across the countryside throughout the courtship season. In mid to late winter, other owls add their voices to the nighttime soundscape.

If you want to get to know these birds better, there are several ways to make your property owl-friendly. You can enhance feeding opportunities by replacing large manicured lawns with unmowed expanses of native grasses and by ensuring that good hunting perches are available along the edges of yards, fields and pastures.

Owls also need roosting sites where they can safely slumber out of sight during the day. Each species has its own preferences for sleeping quarters. Popular choices include tree cavities, the dense foliage of tall coniferous trees and tangled vines such as honeysuckle or grape.

Most important, if you want owls to stay around through spring and summer, is a nest site. Instead of constructing their own nests, owls use ready-made abodes of two basic types: platforms (such as abandoned hawk, raven or squirrel nests) and cavities (old woodpecker nest holes are favourites). Protect potential owl nest sites by not felling trees containing stick nests or woodpecker cavities. Dead or declining trees that have future real estate value for woodpeckers - and, later, owls - should also be retained.

Some owl species will also happily use nest boxes or platforms and since owls start searching for nest sites in winter, fall is the best time to install these. Act now and you could soon be hosting owls in your own backyard.