Evening Grosbeak

The Evening Grosbeak is a stocky, heavy-billed finch of northern coniferous forests. Often moving in large flocks, this boldly coloured bird with a massive bill is difficult for observers to miss. An irruptive migrant across much of its range, it makes roughly biannual appearances at winter-feeding stations throughout much of its boundaries within the United States. It is a year round resident of North America breeding primarily in Canada.

Adult Male (spring/summer)

Brownish-black head with black crown and distinctive yellow forehead and supercilium. Dark brown nape, back, and mantle give way to yellow scapulars and rump. Upper tail coverts are black. Wings are black except for white secondaries and tail is black. Brownish throat and upper breast give way to bright yellow lower breast, belly and undertail coverts. Bill is massive and pale ivory. Legs pink.

Adult Female (spring/summer)

Head grayish brown, with black lores and supraloral. Massive olive-gray bill. Greenish-yellow tinge to neck and flanks; mantle, rump gray-brown; chin, breast belly gray-brown; undertail coverts buffy white; wings black with white at base of primaries; pale white on greater secondary coverts, secondaries and tertials. Tail is short with white tips on rectrices. Ends of upper tail coverts have white spots.

Juvenile

Juveniles resemble adult females.

General:

The Evening Grosbeak is a large and brightly colored finch. Length: 16-18cm. Wing: 30-36cm. Weight: 53-74grams.

Behaviour:

The Evening Grosbeak is a social bird found in flocks, particularly in winter. They forage high in treetops and are often heard before seen. Diet consists of insect larvae during the summer and seeds, buds berries and fruit during the winter. During some winters they are common visitors to feeders.

Habitat:

Erratic movements are made in some winters into the United States being common at feeders. Otherwise they winter and feed in coniferous and deciduous forests often at higher elevations. During breeding they occupy deciduous, coniferous and mixed forests of northern North America and the mountains of the west.

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. The nest is flimsy and saucer-shaped made of small twigs and roots lined with grasses, fine roots, lichens or pine needles and built mostly by the female. The clutch is 2-5 light blue to blue-green with brown or purplish blotches. 1 to 2 broods.

Similar species:

Pine Grosbeak, American Goldfinch.

Conservation Status:

Listed as Least Concern however, populations have dropped steeply, particularly in the east.

Capture Rates

Evening Grosbeaks prefer the habitat of coniferous and deciduous forests seen outside the area of the Colony Farm banding station. A rare visitor to the station during migration with few individuals passing through.

Molt Summary:

PF: HY partial (Aug-Nov): PB: AHY complete (Aug-Nov); PA absent-limited (Mar-May).

Molt occurs primarily on the summer grounds.

Preformative molt includes most to all med covs and 5 – 10 inner gr covs, but no terts or rects.
PAs: include no gr covs or flight feathers.

Juvenile has dingy grayish or brownish plumage, yellow inner gr covs, and a dusky bill. Juveniles can be sexed by the pattern of white on pp, s5-s6, and the rects.

This ASY male in May is showing a uniformly adult wing with no obvious contrasts between feather groups. Notice the broad, truncate and glossy black primary coverts and visible primaries with thick, glossy black rachises and the extensive white wing patch. Notice also the the very fresh visible remiges (primaries and secondaries) with little or no wear to the tips of these feathers.