Lifestyle and Habits
Last Review/Updated: May 31, 2002
Owls are birds of prey that are especially adapted for hunting at night. Their large eyes enable them to see well under low light conditions. The eyes face forward in a flat, broad-feathered, "facial disk," not found in other birds. In this way, both eyes see the same object at the same time, providing the bird with binocular vision. Binocular vision enables an owl to judge distances between objects and thus increases the bird's ability to maneuver in a crowded environment. Since the eyes are immovably fixed in their sockets, an owl must turn its head to follow moving objects. This motion is aided by a long and flexible neck that allows the owl to turn its head more than 3/4 around.
Along
with their excellent sight, owls also locate their prey with an acute
sense of hearing. The openings to the ears are large, and hidden behind
the facial disk. The right ear is positioned high on the head, while
the left ear is low. In this way, sound reaches one ear before the
other, and the owl is able to detect exactly where the sound is coming
from. In experiments performed in totally dark rooms where eyesight
is useless, owls have caught mice on a leaf-littered floor with 100%
accuracy.
Many owls have long feathers on top of their heads that are called "ears" or "ear tufts." These are not connected to the ears, and are not used for hearing.
Owls fly on soft and silent wings. They can maneuver among trees and shrubs, and drop on their prey without warning. Soft, comblike projections on flight feathers effectively muffle the sound of air passing over the wings. The wings of other raptors (hawks, eagles) are not so equipped, and make flapping sounds in flight. Hawks and eagles depend more on speed than stealth to catch their prey.
Like other raptors, owls have strong feet with sharp, curved talons used for grasping and carrying prey; and they have strong, hooked beaks for tearing flesh.
Although
most owls are active at night (nocturnal), some also hunt by day (diurnal).
Many owls migrate to the southern portions of their breeding range to spend the winter. Others, like the great horned and pygmy owls, are resident in Alberta throughout the year, only marginally moving to more favorable hunting areas in winter. The snowy owl migrates from the Arctic to spend the winter in Alberta.
All species of owls lay plain white eggs. These are laid over a period of several days. Incubation, and thus embryo development, begins with the laying of the first egg. Eggs hatch over a period of several days. Older nestlings are larger and have a greater chance at survival than younger, smaller ones. This contrasts with the nesting habits of upland game birds and ducks, where incubation does not start until the last egg is laid. All young hatch at about the same time, and all have an equal chance at getting enough food. Young owls are cared for by both parents. Nestling owls are very demanding, having enormous appetites. They can eat their own weight in food in a single night.
All owls found in Alberta belong to one family (Strigidae). Size varies from that of the tiny pygmy owl, 16 cm (6 in.) long, to the great grey owl, which can measure up to 84 cm (33 in.) in length, with a wingspread of 120 cm (47 in.).
