Vancouver Avian Research Centre

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Species: Evening Grosbeak Coccothraustes vespertinus
 

Description:

The Evening Grosbeak is a stocky, heavy-billed finch of northern coniferous forests. An irruptive migrant across much of its range, it makes roughly biannual appearances at winter feeding stations throughout much of the coterminous United States. Often moving in large flocks, this boldly colored bird with the massive bill is difficult for observers to miss.


Identification:

General: The Evening Grosbeak is a large and brightly colored finch and a noticeable winter visitor to bird feeders during irruption years in some winters when it may wander as far south as the southern U.S.

Large finch with robust proportions. Massive bill and distinctive plumage characteristics separate Evening Grosbeak from most other species within its range. Total length 16.5–18.0 cm; mass 53–74 g. Tail relatively short, slightly notched. Massive conical bill pale greenish yellow (color more intense in spring). Plumages do not change throughout the year.

Adult Male: Male has brownish-black head with black crown and distinctive yellow forehead and supercilium. Dark brown nape and back give way to yellow scapulars and rump. Upper tail-coverts black. Wings and tail black with large white wing patch on inner coverts and tertials. Brownish throat and upper breast give way to brownish-yellow underparts.

Adult female: Female head and upperparts mostly grayish brown, with weak black malar stripe and yellowish wash on sides of neck. Upper tail-coverts black with white spotting. Wings and tail black with white and gray wing patch on inner coverts and tertials, smaller white panel across base of inner primaries, outer rec-trices white-tipped. Throat and underparts pale grayish brown, with white under tail-coverts.

Juvenile: Juveniles resemble adult females.

Similar Species: Bramblign Fringilla montifringilla but different distribution and colouration.

Behavior: During the breeding season, this species is quite secretive, and courtship occurs without elaborate song or display. This secretiveness, together with a spare, flimsy nest placed high in a tree, makes it a difficult subject of study. As a result, comparatively little is known of the species’ life history.

Habitat: Breeding: common in mixed-conifer and spruce forests, less common in pine Less closely tied to coniferous tree species than other carduelines—also uses deciduous species for nesting and food.

Information:

The breeding range of the Evening Grosbeak underwent a significant expansion in historic times. The contemporary scientific literature documented eastward movement, with the species regularly appearing in areas east of its known range, perhaps a result of the establishment of box elder (Acer negundo) in eastern cities as an ornamental planting. The abundant seeds of the box elder persist on the tree through the winter, providing a stable food supply. Outbreaks of forest insects may also have allowed this bird to extend its breeding range to the east. The Evening Grosbeak was an object of much interest from the late 1800s to the mid-1900s, largely as a part of natural history and banding studies resulting from its eastward range expansion. Comparatively few recent studies have been conducted—surprising considering the species’ extensive range.

Conservation Status:

BC Yellow, COSEWIC n/a, Global G5 (1996) Killed in collisions with residential windows in approximate proportion to their presence at feeders in winter; Evening Grosbeak accounted for 3.3% of individuals present and 3.7% of individuals killed in continent-wide survey. Large numbers sometimes killed by vehicles when flocks are attracted to grit and salt on roads. At least 2,000 dead adults on 16-km stretch of highway in British Columbia, with many more dead off-road (Smith 1981).
 
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