Vancouver Avian Research Centre

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 Species: Brewer’s Sparrow Spizella breweri
 

Description:

The Brewer’s sparrow is our smallest sparrow. It is long-tailed, slim and small-billed. Its plumage is subtle and undistinguished with weak facial contrast.

Two species are generally recognized, S. b. breweri and the ‘Timberline’ sparrow, S. b. taverneri. Each has different breeding ranges, which may overlap, and have subtle plumage differences. The breeding ranges are eastern Alaska, Yukon, central south B.C., east to southeast Saskatchewan, south to New Mexico, Arizona and south central California. It is absent from the coastal pacific areas and winters in southwest U.S. and northern Mexico.

Identification:

General: The head is very subtlety streaked. The supercilium is pale dull gray to dull whitish. The eye is dark with a white eye ring. Moustachial and malar stripes are thin and brown. The bill is small, conical, pale brown with dusky tip. Nape and mantle streaked. The rump is brown with dark brown streaks. Wings are brown with poorly defined wing bars. Tail is long, notched and brown. Underparts are pale and unstreaked, breast and flanks dingy gray, sometimes lightly streaked under the wings. The belly is dull white, legs and feet are pale pink or pale horn colour. Length: 12-13cm. Weight: 10.5g.

Adult Male: No distinguishing differences between male and female.

Adult Female: No distinguishing differences between male and female.

Juvenile: Similar to adults but less streaked above with breast and flanks narrowly streaked with black triangular markings.

Similar Species: Clay-colored Sparrow is similar but Brewer’s is plainer, drabber with less contrasting nape and more conspicuous white eye ring. Chipping Sparrow has a rusty cap during breeding, a white supercilium and black eye stripe. Clay-colored and Chipping are similar in size and shape.

Behaviour: Quite inconspicuous on the breeding ground where most activities take place undercover of vegetation. Hops on ground; occasionally runs. Hops or clambers about among twigs and branches within shrubs. Main foods taken are small insects, mainly gleaned from foliage and bark of shrubs or dwarf trees; also seeds usually taken from ground. Although its bill morphology is typical for a sparrow, much of this species’ diet consists of arthropods. As benefits an arid land species, its water economy is excellent and can exist for long periods without drinking.

Habitat: Breeds in a variety of habitats, but in the southern parts of their range they prefer big sagebrush and silverberry in short grass. The northern population is found in subalpine fir and krummholz. Winters in loose flocks in arid brushy areas with patches of grass.

Information:

John Cassin named this sparrow in 1856 in honor of his friend, Thomas M. Brewer.

Shortly after arrival on the breeding grounds Brewer’s pairs build a small open-cup nest in sagebrush and lay 3 bluish-green marked with brown, eggs.

Conservation:

Numbers have dropped by about 60% since 1961; the reasons for this are unclear, but reflect habitat destruction.
 
Capture Rates


Brewer’s Sparrow breeds in the landscape of the intermountain west dominated by sagebrush. Therefore, it is vagrant visitor to Colony Farms as is reflected by the low capture rate in June and zero capture rate for the remainder of the year. Capture rates are standardized as birds captured per 100 net hours from 2010 - 2012.

 

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