Bird of the Month: Evening Grosbeak
By Hugh Jennings
Scientific Name: Coccothraustes vespertinus
Length 8 in
Wingspan 14 in
Weight: 2.1 oz
AOU Band code EVGR
The Evening Grosbeak (EVGR) is about 8” long with a wingspan of 14” and a weight of 2.1 oz. (60g). The genus name Coccothraustes (cock-oh-THROUSE-teez) is Latin from the Greek kokkos, grain, and thrauein, to shatter. The species name vespertinus (ves-per-TINE-us) is Latin meaning “belonging to evening” from the mistaken belief that this bird sang mainly in the evening.
The EVGR has a massive head and bill, short tail and relatively short but pointed wings. The male has a yellow body, darker head with a bright yellow eyebrow and black-and-white wings. The bill is yellow in winter and pale green in summer. The female is brownish gray overall, with yellow on the nape and black-and-white wings. The bill is the same as the male.
This large finch wanders widely in the winter, descending on bird feeders in colorful, noisy flocks and consuming large amounts of sunflower seeds. Originally, it was a western bird and almost unknown east of the Great Lakes before the 1890s. It now breeds commonly east to New England. Its eastward spread may have been due to the planting of box elder trees which is favorite food of the grosbeaks.
In Washington state it is a fairly common summer resident in low- to mid-elevation conifer forests statewide, somewhat irregular in winter but usually uncommon. They are on the move in spring and a common visitor to deciduous trees for the buds, and to bird feeders. Numbers in any locality can vary from year to year.
Seeds make up most of their diet, especially of box elder, ash, maple, locust trees, etc. The large bill makes it easy crack large seeds with ease. They also feed on oozing sap and insects in summer. The EVGR also will eat fine gravel for minerals and salts and therefore can be seen near gravel piles. They forage mostly in trees and shrubs and sometimes on the ground. They usually forage in flocks, except when nesting.
The song is a halting warble while its call is a ringing “peeer” and when given by a flock sounds like sleigh bells. During courtship, the male dances with head and tail raised, wings drooped and vibrating as he moves back and forth. The male frequently feeds the female.
The nest is usually on a horizontal branch well out from the trunk or in a vertical fork of a tree. The height is usually 20-60 feet above ground, but can vary from 10-100 feet. The nest is made by the female and is a loosely made cup of twigs, lined with fine grass, moss, rootlets or pine needles. Usually 3-4 eggs, but sometimes 2-5, are laid. The eggs are pale blue to blue-green, spotted with brown, gray or purple. Only the female incubates the eggs for 11-14 days. The male may feed the female during this time. Both parents feed the nestlings which leave the nest about two weeks after hatching. They may have two broods in one year.
The EVGR usually lives 4-9 years. One male banded in Pennsylvania was trapped and released in New Jersey when over 13 years old. One female in an aviary in Canada lived to at least 17 years.