OWL, common name for birds of prey of the order
Strigiformes. There are two families: Strigidae, the
typical owls, with about 167 species; and
Tytonidae, the barn owls, with about 14 species
(see BARN OWL). There are anatomical differences
between the two families, but many generalizations
apply to both.
The large eyes of owls (smaller in barn owls) are
directed forward, and are encased in a capsule of
bone, the sclerotic ring, that allows little eye
movement. Owls must turn their entire heads to
look sideways, facilitated by relatively long and
flexible necks that permit the head to be rotated
through 270 degrees. In most owls the eyes are
surrounded by a facial disk of stiff feathers. As
relatively few owls hunt their prey in full daylight,
their hearing is particularly important. Many owls have asymmetrical skulls,
with the
ear openings at different levels; this enables the bird to get a "fix"
on the sound
made by a prey animal.
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