I ended my column last week with a brief note about the unusually high number of snowy owls that have been sighted here in Pennsylvania this winter.
While researching that phenomenon, I was struck by what fascinating creatures owls really are. There are 199 species of owls worldwide, and they live on every continent except Antarctica. Exactly 41 species of true owls are found in North America, and besides the transient snowy owl, seven other owls are common in Pennsylvania.
Our largest native owl is great-horned owl at 18 to 25 inches long and a wingspan of 36 to 60 inches. Even folks who have never seen of these big birds with their prominent ear tufts have probably heard its deep, mellow "hoo-hoo-hooooo" call on some quiet evening.
Great-horned owls are common throughout Pennsylvania and prefer upland forests away from human development. Because of their size, great-horned owls can catch a variety of prey that includes small mammals up to the size of a skunk, and they are seemingly undeterred by a skunk's foul-smelling defense mechanism. They will also take turkeys, ducks, geese and even other owls.
The barred owl is also a large bird, measuring 17 to 24 inches long with a wingspan of 50 to 60 inches. Barred owls are quite vocal, and their call is distinctive and unforgettable, often described as sounding like an eerie "Who cooks for you?"
These birds have a large head with no ear tufts and dark brown eyes, and their overall coloration is dark brown with light bars. Barrd owls prefer deep woods and forest areas near waterways
Barn owls are 14 to 20 inches tall with a wingspan of 42 to 44 inches and are the most unusual looking of all Pennsylvania owls. They are light colored overall with a strange looking white, heart-shaped face, which is why they are sometimes called "monkey-faced owl."
Barn owls prefer open areas and grasslands where they nest in barns, abandoned buildings and hollow tree cavities. They tend to have a short life expectancy of two years or less, so barn owls have a higher reproductive rate than most other owls. In spite of that, the species has experienced declines throughout Pennsylvania in recent years.
Because they target mice, rats and other pesky rodents as food and may eat twice as much of this prey based on their weight as other owls, barn owls are considered especially beneficial around farms and other human developments.
The long-eared owl is a crow-sized bird about 13 to 16 inches long with a wingspan of 36 to 42 inches. They resemble a smaller version of the great-horned owl, although its ear tufts are closer together. Long-eared owls prefer dense vegetation and shrubs near open areas. It is one of our most nocturnal owls, and I've never been lucky enough to see one of them yet myself.
At only 7 to 10 inches long with a wingspan 18 to 24 inches, the eastern screech-owl is the smallest eared owl in Pennsylvania. Screech-owls exhibit both red and gray color phases.
Although the gray phase tends to be the most numerous here in Pennsylvania by about 10 to 1, most of the screech-owls I've seen have been the red variety. These small owls prefer forests and the wooded borders and hunt by flying low over fields and meadows rather than from a perch.
The northern saw-whet owl is our smallest owl at just 7 to 9 inches long and a wingspan 17 to 20 inches. This tiny owl has a small head with no ear tufts and is gray-brown with light spots and streaks. Its name comes from the high-pitched call it makes when alarmed, which sounds something like a saw being sharpened.
The saw-whet is also the owl featured on the first conservation license plates issued in Pennsylvania some year ago.
The short-eared owl is a medium-sized owl, 13 to 17 inches long and a wingspan of 36 to 44 inches, with a large round head and small, barely visible ear tufts, and dark brown overall with buff streaks and spots. They breed as far north as the Arctic tundra and are almost strictly wintertime migrants here in Pennsylvania.
Short-eared owls prefer open areas similar to its summer range and will often been seen hunting during the day. I was fortunate enough to see a short-eared owl just before dusk a few winters ago in western Pennsylvania.
Most owls are believed to mate for life, but aside from the breeding season, these birds live a generally solitary existence. They have large eyes that face forward giving them binocular vision and exceptional depth perception.
The specially adapted soft edges of their wing feathers enable owls to fly almost silently, which allows them not only to hear their prey while in flight but also to dive on it undetected.
Owls have incredible hearing, and some species, such as the barn owl and long-eared owl, have one ear located higher on the head than the other. This asymmetrical positioning allows the bird to pinpoint prey by triangulation, even under snow.
Many species of owls swallow smaller prey items whole and then regurgitate feathers, hair, bones and other inedible parts as "owl pellets," which are often found on the ground beneath roost trees and other daytime perches.
In winter, owls will catch extra prey when available and allow it to freeze, and then use their own body heat to thaw and eat the food later. These and other adaptations make owls among the most efficient and effective predators, day or night.