The birds spend most of their lives in the spruce forests north of Wisconsin. There, the female builds a loose cup-like nest of sticks lined with moss and rootlets. The nest, placed six to 70 feet above the ground is usually concealed in an evergreen but may occasionally be constructed in a deciduous tree. The female lays two to five eggs, blue to blue-green spotted with purples browns or grays. The incubation period is unknown but is believed to range from 12-14 days.
Young birds fledge two weeks later.
Though primarily seed-eaters, evening grosbeaks consume insects including beetles and many spruce budworms during summer. Their natural vegetable diet includes seeds from spruce, fir, maple, elm, box-elder and ash supplemented by tree buds, berries and apples. If natural seed and fruit supplies remain plentiful during winter, evening grosbeaks will overwinter up north. In years where seeds are in short supply, the grosbeaks wander in search of food. Where they go is unpredictable, but the population may irrupt in large numbers when gregarious flocks appear anywhere in the eastern United States.