Written by Peter Pearsall/Photo by Barbara Wheeler
The evening grosbeak is a large, colorful finch of northern conifer forests. Often found in large, chirping flocks, they feed primarily on seeds but also consume insects in summer, particularly spruce budworm, a tree pest native to northern forests.
In some years, Malheur Refuge is host to thousands of grosbeaks migrating to and from breeding grounds in montane forests beyond the Refuge. Other years, not a single evening grosbeak is seen.
Evening grosbeaks migrate with shifts in food supply. If there are ample seed resources in their breeding range in the northern boreal forest, they’ll stay put all year. But if food grows scarce, grosbeaks will travel far and wide in search of it, making wandering movements called irruptions.
Prior to the mid-1800s, evening grosbeaks were uncommon to rare east of the Rocky Mountains. By the 1920s, they were considered a regular winter visitor to New England. Many believe that the widespread planting of ornamental box elder trees in the eastern U.S. facilitated this range expansion, which has since largely contracted, for unknown reasons.
(The name “evening” is a misnomer applied to the bird when it was first described to science in 1825. Because the species was rarely seen by naturalists working in the Eastern U.S., its first observers mistakenly believed that these grosbeaks vocalized at night and dwelled in swamps—neither of which is true.)
As climate change brings warmer temperatures and unpredictable rainfall, North America’s boreal forest is threatened by drought, increased risk of wildfire, and pest infestation. The year-round boreal forest habitat that evening grosbeaks depend on faces an uncertain future.