Smallest owl in the world is the six inch elf owl of the Southwestern United States and western Mexico. Largest around is the great gray owl which can be found in the deep woods of Canada and Alaska as far north as trees grow. He's a giant 30 inches in height and sports a pair of wings that spread up to 60 inches from tip to tip.
About 525 different varieties of owls can be found. Except for a few oceanic islands and in the Antarctica, you'll find owls just about everywhere including temperate spots, tropical locations and even in subarctic regions.
Most owls live alone. They sleep during the daytime and hunt for food at night. They are less active in winter when their food needs are less, but for the most part they stay right at home and don't move on to warmer areas. A number, however, do migrate south in winter.
One of the exceptions is the snowy owl who lives above the Arctic Circle in summer where there is continuous daylight. He hunts during the daytime in both summer and winter. During the cyclic low that happens once every five to seven years, the snowy owl is forced far southward in winter in search of food. They have been spotted in winter as far south as the British Isles, northern Germany, central Russia, southern Siberia, northern Japan and even in the central and eastern parts of the United States.
The snowy owls are swift enough to catch and kill ducks on the wing. Their diet mainstay, however, consists of lemmings and arctic hares. When rabbit and lemming cycles wane, the owls adjust their living habits accordingly. In normal years when the hunting is good they lay between seven and ten eggs. In bad years, however, they lay only two or three and occasionally make no attempt to nest at all.
Farmers love owls. The birds destroy harmful mice, rats and moles.
Owls usually swallow their prey completely, pulling the catch apart into chunks that can be swallowed easily. Later they throw up pellets of bones, fur and features that cannot be digested. These pellets can usually be found under an owl's roosting place.
Another of the migrating owls is the long eared owl which is found from southern Canada to Southern California and Virginia during the summer. In winter he travels as far south as Florida.
The short eared owl also migrates in winter. In summer you'll find him any place from the Arctic south to California, Kansas and New Jersey. He spends his winter in Central America.