IV.

Types of Owls

Some genera of owls have many species—the largest genus, otus, contains more than 35. Some owls of this genus are well known, such as the eastern screech owl of eastern North America and the Eurasian scops owl, a strongly migratory species that breeds in southern Europe as far east as Lake Baikal. Many of the tropical species, however, are known from only a few museum specimens, and their habits have not been studied. The forest owlet was believed to be extinct for 100 years until it was rediscovered in central India in 1997.

All species belonging to the largest genus of owls look much alike and, as might be expected in nocturnal birds, are differentiated most strongly by their distinctive voices. Owls may hoot, whistle, screech, or click and they are particularly noisy while courting.

Among the largest species of owls are the eagle owls. They have tufts of feathers on their heads that are called “ears” but are not related to true ears. There are several species in Europe, Africa, and Asia but only the great horned owl is found in the Americas. Most widely distributed is the northern eagle owl, found from Scandinavia and Spain to Japan. It is about 71 cm (28 in) long. The snowy owl of northern Eurasia, in which the female is white with few black spots on the back and the male pure white, is unusual in feeding by day (mostly on lemmings). The northern hawk owl is also a daytime hunter.

Smallest of the family are the elf owl of the south-western United States and Mexico—it is only 13 cm (5 in) long, and nests in deserted woodpecker holes in large cacti—and the Eurasian pygmy owl, 16 cm (6.5 in) long.

Scientific classification: Owls make up the order Strigiformes. Typical owls make up the family Strigidae, and barn owls make up the family Tytonidae. The common barn owl is classified as Tyto alba, and the burrowing owl as Speotyto cunicularia. The largest genus of owls is Otus. The eastern screech owl is classified as Otus asio, and the Eurasian scops owl as Otus scops. The forest owlet (or Blewitt’s owl) is classified as Heteroglaux blewitti. Eagle owls make up the genus Bubo. The great horned owl is classified as Bubo virginianus and the northern eagle owl as Bubo bubo. The snowy owl is classified as Nyctea scandiaca and the northern hawk owl as Surnia ulula. The elf owl is classified as Micrathene whitneyi and the Eurasian pygmy owl as Glaucidium passerinum.