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Birds of Yosemite National Park (1954, 1963) by Cyril A. Stebbins and Robert C. Stebbins


OWLS: Order Strigiformes

TYPICAL OWLS: Family Strigidae

SCREECH OWL
SCREECH OWL
SCREECH OWL (Otus asio): 8-10 in. Above gray, finely streaked with black; below lighter, streaked and barred with black; “ear” tufts at sides of head, wanting in immature in summer; large yellow eyes. Song a low-pitched whistle with notes near one pitch; notes stacatto, beginning slowly, accelerating, and dropping slightly in pitch. Nests in tree cavities, often those dug by large woodpeckers.

Frequents oak woodland, broken coniferous forest, and willow and cottonwood stream-borders. R. below about 5,000 feet elevation in the western part of the Yosemite region. Found in Yosemite Valley, especially among canyon live oaks.


GREAT HORNED OWL
GREAT HORNED OWL
GREAT HORNED OWL (Bubo virginianus): 18-25 in. Above mottled with gray and brown; throat white; rest of under parts with narrow wavy black bars on whitish; horn-like “ear” tufts; large yellow eyes. Voice a deep, resonant, low-pitched whoo too-whoo whoo whoo, all essentially on one pitch. The female has a higher pitched voice of more variable pattern.

R. in a variety of habitats from wooded areas to desert cliffs, occurring from sea level to timberline. Widely distributed in the Yosemite region, largely below the Hudsonian life zone but occasionally in this zone. Observed at Ten Lakes and at 10,700 feet on the Lyell Fork.


PYGMY OWL
PYGMY OWL
PYGMY OWL (Glaucidium gnoma): 7-7 1/2 in. Above dark, brownish-gray with whitish spots, most abundant on head; throat white; below white, streaked with fine black lines; tail long for owl, barred with white; projecting back at angle when bird is perched; no “ear” tufts; eyes yellow. Voice a slow series of mellow whistled notes often on one pitch, occasionally interrupted with a rapid series—whoot, whoot, cahoot, tootoo-too-too-too-too, whoot, whoot, etc. May be heard in the daytime. Often nests in woodpecker holes. Most active in early morning, later afternoon, and at dusk. Smallest owl in Yosemite.

Frequents open coniferous and deciduous woods chiefly in the Transition and occasionally in the Canadian life zone in the mountains where it is a permanent R. Common in the Yosemite region.


LONG-EARED OWL
LONG-EARED OWL
LONG-EARED OWL (Asio otus): 13-16 in. Above mottled dark brown, buffy, and gray; below yellowish-brown and white with streaks and bars of dark brown; catlike face; brown patch on tawny lining of wing near tip seen in flight; long “ear” tufts immediately over eyes. Song a low, pidgeon-like whooo, given singly, often with lengthy intervals. Cat-like meowing notes may be heard if the birds are disturbed at the nest. Often uses abandoned crow or magpie nests for nesting.

Frequents thick foliage, particularly willow thickets, groves of aspen or cottonwoods, or dense stands of young conifers. R. in the Yosemite region below the Canadian life zone. Observed in Yosemite Valley and at Swamp Lake.

GREAT GRAY OWL (Strix nebulosa): 24-33 in. Large, light gray facial discs marked faintly with dusky concentric rings; eyes yellow; no “ear” tufts; above dark brown with light grayish mottling; under parts light gray streaked lengthwise with dark brown. Voice a deep reverberating whoo given at it regular intervals. Yosemite nesting records near Glacier Point and at Crane Flat. Largest owl in Yosemite region.

R. with some wandering in winter. Chiefly in coniferous forests of the Sierra Nevada from Madera County northward. Probably permanent R. in Yosemite region where it has been observed in fir and pine woods in the Canadian zone.

SHORT-EARED OWL
SHORT-EARED OWL
SHORT-EARED OWL (Asio flammeus): 13-17 in. Above mottled yellowish-brown and dark brown, streaked on head and neck; below buffy streaked with dark brown, conspicuously so on chin and breast; buffy patches on upper surface of wings; under surfaces of wings buffy with dark mark toward tip; facial discs dark around eyes, fading into gray; inconspicuous “ear” tufts. Forages in the daytime.

Usually occurs in marshy land and open fields. Rare C. V. to Yosemite region. Has been seen at 11,000 feet on Mount Clark.

SPOTTED OWL (Stria occidentalis): 18-19 in. Upper parts rich brown, spotted with white; eye discs light brown, tinged with yellow, bordered with dark brown; no “ear” tufts; under parts yellow brown, heavily barred and spotted with white; tail barred and tipped with whitish; eyes dark. Call resembles the barking of a dog.

R. in dense forests of the Transition life zone of the Sierra to about 7,000 feet. Has been observed in Yosemite Valley.

SAW-WHET OWL (Aegolius acadicus): 7-8 in. Above brown, spotted with white; “ear” tufts. absent; top of head and neck with fine white streaks on brown; white over eyes; under parts with strong, reddish-brown bars on whitish; white spots on wing; tail inconspicuous, with white bars. Immature: Chocolate brown above; tawny below, with dark streaks; sooty face with white “eyebrows.” Call a long series of staccato notes, near one pitch but varying in volume.

Frequents woodland and coniferous forests of the Transition and Canadian life zones. Sparse R. in Yosemite region. Recorded as nesting in Yosemite Valley.



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