The Evening Grosbeak is a songbird without a song. It is a social bird that forages in flocks in winter, before breaking off into small groups or pairs during the breeding season. It is a resident bird of Western Washington. Its presence is irruptive and irregular, such that one year might see many more birds than the next. The Evening Grosbeak can usually be seen in Edmonds annually.
Habitat for the Evening Grosbeak includes conifer forests and mixed deciduous forests that include box elders, other maples, and fruiting shrubs. Seeds make up the bulk of its diet, especially from box elder, maple, ash, locust, and other trees. It also feeds on the buds of deciduous trees, berries, other small fruits, and weed seeds. By breaking off small maple twigs, it then feeds on sap that it causes to ooze. Summer insects include spruce budworm larvae, caterpillars, and aphids. When wintering in urban areas, this species is most abundant in small woodlots near bird feeders. It is particularly fond of sunflower seeds and will come to large tube feeders and platform feeders.
With its enormous bill, the Evening Grosbeak can crush seeds that are too large for Pine Siskins and Common Redpolls to open. These smaller birds will often follow grosbeaks to glean the food scraps they leave behind. The Evening Grosbeak will use its bill to manipulate fleshy fruits such as cherries. It removes the skin and flesh before cracking and swallowing the pit.
Courtship displays involve movement rather than song. The male will dance with his head and tail raised, his wings drooped and vibrating, as he swivels back and forth. He will also feed the female. Both members of the pair will alternate bowing to each other. The male does not have a complex song with which he can defend his territory or attract a mate.
Breeding takes place in mature and second-growth conifer forests of northern North America, including the Rocky Mountains. The nest is usually on a horizontal branch, 20-60 feet above ground. Built by the female, the nest is a loosely made cup of twigs, lined with finer materials.The female incubates her three to four eggs for about two weeks. The male will feed the female during incubation. Both parents feed the nestlings. Young birds leave the nest about two weeks after hatching. This species has one or two broods per year.
The oldest Evening Grosbeak of record was a male, at least 16 years and three months of age when he was found in New Brunswick in 1974. He had been banded in 1959 in Connecticut. The collective noun for a group of grosbeaks is a gross.
The Evening Grosbeak is on the 2016 State of North America’s Birds Watch List. The watch list includes species that are most at risk of extinction without significant conservation actions to reverse declines and reduce threats. Its population declined steeply between 1966 and 2015. The global population is estimated at 4.1 million birds, with 71 percent spending part of the year in the U.S., 57 percent in Canada, and 5 percent in Mexico.
Population declines may have several causes. Logging and other development in the boreal forests may disrupt breeding and feeding. The species may be impacted by aerial spraying of forests in the U.S. and Canada to reduce spruce budworms and other insects that are foods of choice for the Evening Grosbeak. The spruce budworm is considered a significant forest pest. Disease outbreaks such as salmonella, West Nile virus, and House Finch eye disease can also affect the Evening Grosbeak population.
You can listen to the calls of two Evening Grosbeaks here: www.xeno-canto.org/110121.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.