Laura Erickson's For the Birds

(Recording of Evening Grosbeaks)

As many people who keep their feeders going through the summer know, the grosbeaks are back. We in Duluth are among the fortunate few in the United States who can see Evening Grosbeaks year round. They are gregarious and noisy—even if you don’t have a feeder, you can often hear their flocks flying overhead. They are one of the many species of birds which are incorrectly named: it was originally thought that they sang only in the evenings, but as the birds in my yard can attest, they call throughout the day.

(Recording of Evening Grosbeaks)

According to some bird books, Evening Grosbeaks also sing a song similar to the song of Purple Finches, but that’s probably an error—because the two birds are often found together, early naturalists may have heard one species while looking at the other.

Evening Grosbeaks are fond of maple seeds and especially box elder seeds—when people in Duluth tell me that they just can’t seem to attract grosbeaks to their feeders, they invariably don’t have box elders in their neighborhood. Once grosbeaks discover a feeder of sunflower seeds, they quickly become the most abundant species in the yard. They drink a lot of water, too, so bird baths are very popular with them. In winter, they are frequently attracted to the salt spread along roads and highways—and are often killed by cars because of this.

In July and August, when young grosbeaks are first learning about bird feeders, many are killed crashing into windows. If you have this problem, try hanging silhouettes of flying hawks on your windows, or dangling long strips of aluminum foil or cloth to the outside of the window frame. Closing the drapes sometimes helps, too.

Grosbeaks are one of the most gregarious of birds. Once the young fledge, usually in July, families join larger flocks. They seem to believe in the old-fashioned extended family tradition—the babies are cared for by all the adults. I’ve watched one baby beg for food from, and be fed by, four different males and three females while sitting in my feeder. Although the babies are full grown by the time they start visiting feeders, they are easy to tell from the adults—all adult Evening Grosbeaks have green beaks in spring and summer. Perhaps the beak color is the cue young birds use so they’ll recognize the soft touches.

A unique phenomenon sometimes occurs in Evening Grosbeaks—gynandromorphism. A gynandromorph is a bird that is genetically half male and half female. Quite a few Evening Grosbeaks have been found in the eastern U.S. over the years with this condition. On one side of the body, either right or left, a bird might be a male—with male plumage on the outside and male sex organs on the inside. An examination of the chromosomes of cells on this side of the body would indicate that the bird was a male—but on the other side, as if a line were drawn along the exact center of the bird, it’s a perfectly normal, healthy female.

This peculiar phenomenon has been written up in ornithological journals and textbooks, but, surprisingly, has never caught the attention of the editors of the National Enquirer.

(Recording of an Evening Grosbeak)

This is Laura Erickson, and this program has been “For the Birds.”