Owls

Classification

There are two major groups of birds of prey, or raptors, in the world:

  • Order Falconiformes – The largest group is made up of raptors are active during the day (diurnal) and includes the falcons, hawks and eagles.
  • Order Strigiformes – This group is made up of raptors that are adapted to hunt their prey at night (nocturnal). Owls are included in this group. All owls found in Alberta belong to one family (Strigidae).

Characteristics

Owls have several adaptations for hunting at night:

Sharp night vision

  • The large eyes of owls 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. Both eyes see the same object at the same time, providing owls with binocular vision which allows them to judge distances between objects. This increases the bird's ability to manoeuvre 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 three-quarters of the way around.

Owl skull showing placement of ear openings

Superior hearing

  • 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 percent 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.

Silent wings

  • Owls fly on soft and silent wings. They can manoeuvre among trees and shrubs, and drop on their prey without warning.
  • Soft, comb-like projections on flight feathers effectively muffle the sound of air passing over the wings. Owl feet and talons

Other distinguishing characteristics

  • 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).
  • Size varies from that of the tiny pygmy owl, 16 centimetres (6 inches) long, to the great gray owl, which can measure up to 84 centimetres (33 inches) in length, with a wingspread of 120 centimetres (47 inches).

Reproduction and growth

  • 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 and all young hatch at about the same time, providing 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.

Migration

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 moving relatively short distances in winter to more favorable hunting areas.

The snowy owl migrates from the Arctic to spend the winter in Alberta.

Alberta's owl species

Descriptions for 11 of Alberta's owl species can be found on this website. See:

Related Information

Learn more about owls! See:

 

Page Information

Updated: Jan 8, 2014