Strigiformes


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Related to Strigiformes: Caprimulgiformes

Strigiformes

[‚strij·ə′fȯr‚mēz]
(vertebrate zoology)
The order of birds containing the owls.

Strigiformes

 

(owls), an order of birds resembling Falconiformes in external appearance and biological characteristics but differing from them by the absence of a crop and the presence of long caeca. Owls are crepuscular or nocturnal in habit. The body length ranges from 12.8 cm in the elf owl to 70 cm in the fish owl. The feathers have a long downy base. The soft and loose plumage is most commonly dull brown or reddish; the coloration of males and females is usually similar. The females are larger than the males. Owls have a facial disk of narrow feathers around the eyes. Because the eyes are firmly fixed in the orbits, the field of vision is narrow; the neck’s great mobility, however, ensures a sufficient range of vision. Owls see well in daylight and deep twilight, but their vision is somewhat limited in complete darkness. The openings of the external auditory meatuses are large and usually surrounded by a skin fold; they are often placed asymmetrically, which enables the birds to track prey (for example, rodents) by sound in high grass.

Owls are found throughout the world except in the Antarctic and certain oceanic islands. They inhabit all natural zones, from tundra to desert. Species diversity is most pronounced in forests. There are two families: Strigidae (true owls), with 123 species, and Tytonidae (barn owls), with 11 species. One species of the latter family, the common barn owl (Tyto alba), is found in the USSR.

Although a few species migrate, most owls are sedentary. The birds nest in tree hollows, in the nests of other bird species (for example, crows), on cliffs, on the ground, or in buildings. A clutch usually contains four to six white, almost spherical eggs; some species, for example, the snowy owl (Nyctea scandiaca), lay as many as ten to 14 eggs. One egg at a time is incubated by the female for 25 to 35 days; as a result a nest often contains young of various ages. Owls feed on small mammals (especially rodents), birds, reptiles, and insects. Some species also feed on fishes and crustaceans. The birds swallow their prey whole and regurgitate undigested bones, hair, feathers, and chitin in the form of pellets. Owls are beneficial to agriculture and forestry; they are all protected species.

Eighteen owl species occur in the USSR. Common species are the snowy owl, eagle owl (Bubo bubo), fish owl, hawk owl (Surnia ulula), long-eared owl (Asio otus), short-eared owl (Asio flammeus), tawny owl (Strix aluco), and little owl (Athene noctua).

REFERENCES

Ptitsy Sovetskogo Soiuza, vol. 1. Edited by G. P. Dement’ev and N. A. Gladkov. Moscow, 1951.
Zhizn’ zhivotnykh, vol. 5. Moscow, 1970.

A. I. IVANOV

References in periodicals archive ?
Lymphoma has been described in birds in the orders Anseriformes, Charadriiformes, Columbiformes, Ciconiiformes, Galliformes, Passeriformes, Psittaciformes, Strigiformes, Sphenisciformes, Pelecaniformes, and Struthioniformes.
Most infected birds of species that belonged to the orders Anseriformes, Falconiformes, and Strigiformes were found dead, but a few infections were detected in swab specimens from healthy mallards and feces of wild birds.
Chlamydia spp were not detected in wild birds; however, 4 species (Chlamydia psittaci, Chlamydia pecorum, Chlamydia pneumoniae, and Chlamydia gallinacea) were identified among captive birds (Passeriformes, n = 20; Psittaciformes, n = 15; Rheiformes, n = 8; Falconiformes, n = 2; Piciformes, n = 2; Anseriformes, n = 1; Galliformes, n = 1; Strigiformes, n = 1).
A few cases of sibling pairings have also been documented for species of Passeriformes, Charadriiformes, and Strigiformes, but they represented only 0.
This outbreak confirms that Falconiformes and Strigiformes are sensitive to HPAIV (H5N1) infection and disease (10-12) and shows that numerous species of these orders can be affected by HPAIV (H5N1) (Table 1).
36,37) Between 1980 and 2000, the Geographic National Health Center recorded 335 group mortality events involving 8877 birds belonging to 103 avian species, mainly Falconiformes, Anseriformes, (38) Strigiformes, Passeriformes, and Gaviiformes.
Other orders of birds represented were Falconiformes (hawks, falcons; n = 8, 18%), Strigiformes (owls; n = 2, 5%), Podicepidiformes (grebes; n = 1, 2%), and Charadriiformes (gulls, shorebirds; n = 1, 2%).