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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

The sturdy finch-type beak will turn a beautiful mint green color during the breeding season. beak © Scott Nielsen

February 2001

Big beaks come calling

Colorful evening grosbeaks pack power in their seed-cracking jaws.

Anita Carpenter

The grosbeak's sturdy finch-type beak will turn a beautiful mint green color during the breeding season.

© Scott Nielsen

The winter scene at the backyard feeders is active but not congested as the usual complement of black-capped chickadees, white-breasted nuthatches, dark-eyed juncos, American goldfinches, downy woodpeckers, mourning doves, northern cardinals and blue jays feed side-by-side in relative peace and harmony. Then, unexpectedly, the "big beaks" arrive, disturbing the tranquillity.

Announcing their arrival with loud sparrow-like chips, evening grosbeaks descend en masse upon the feeders as the other birds scatter in all directions. Looking like overgrown goldfinches, the hungry evening grosbeaks dominate the feeding surfaces. They may stay only briefly until some unknown signal triggers their hasty departure, or they may remain for an extended period, returning day after day to empty the replenished feeders.

Evening grosbeaks, Coccothraustes vespertinus, invading your yard are instantly recognized by their chunky, starling-like size and bold yellow, black and white patterned colors. The male is exceptionally striking with a black head highlighted by bright yellow forehead and eye stripe that gives the bird kind of a smug, tough guy appearance. The black head grades into yellow on the lower back , which turns black again at the base of a short forked tail. Bold, clean and large white wing patches contrast sharply with black outer wings. The white wing patches are also visible when the bird flies. The belly feathers are various shades of blended browns and golds.

By comparison, the female appears somberly , but tastefully dressed in silvery gray. She has similar patterns except her yellow and whites are not so bold and crisp, and she lacks the yellow forehead and eye stripe. Winter juveniles resemble females until the young males start turning yellow and developing a hint of yellow in the forehead and eye stripe.

One of their most impressive features, as their common name implies, is a large whitish to yellowish conical finch-type beak that seems to cover the bird's entire face. During breeding season, the beak turns a beautiful mint green color. Regardless of the shade, at all times of the year that beak is an efficient seed cracker. Angled at the base to provide a sharp cutting edge, the super-sized beak provides sufficient leverage to crack such tough seeds as cherry pits or handle such dainty fare as sunflower seeds.

Watch an evening grosbeak feed. The bird selects a seed and deftly positions it in its beak. The beak closes, the seed splinters, a kernel is swallowed and the seed husk is discarded, all within a few seconds. They are such fast, efficient seed-crackers that grosbeaks are gluttons. The quantity of sunflower seeds they may consume during a feeder raid is legendary. A large, ravenous flock may devour 50-100 pounds of sunflower seeds per week.

We don't have the pleasure of seeing evening grosbeaks every winter. 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. Consequently, we never know from winter to winter whether we will see evening grosbeaks.

It's extremely rare for me to discover evening grosbeaks at my feeders in east central Wisconsin. Usually just a few individuals remain only briefly. I'm always hopeful that some day a hungry horde of these gorgeous gluttons will arrive. These big birds with big appetites are always welcome at my feeders

Anita Carpenter keeps the feeders full near her Oshkosh home.