Monday, January 23, 2012

Winter Bird

Pine Grosbeak
Pinicola enucleator

During the winter of 1989-90 snow cover was sparse, so it was easy to walk our woodland trails. On January 2, I heard whistling calls and, in a grove of red cedar trees, spotted a flock of plump, cardinal-size birds with short dark bills. A few were pinkish red with black wings and white wingbars. Most had gray plumage with yellowish green heads and napes. I soon identified the birds as male and female pine grosbeaks. I knew this sighting was unusual, since pine grosbeaks come this far south only sporadically, so I notified Anne Marie Plunkett, who arrived the next day with Ray Glassel and Bob Janssen, both of whom, at three hundred ninety-seven species each, still tie the second-place record for the most species seen in Minnesota. The three friends found the grosbeaks in the same cedar trees where I had seen them.

North American Fringillidae, also known as winter finches, include purple finches, goldfinches, redpolls, pine grosbeaks, red crossbills, white-winged crossbills, and evening grosbeaks, among others. They are small to medium-size arboreal, seed-eating songbirds that fly fast, undulate in flight, have high-pitched calls, and gather in flocks when not nesting. As with the northern owls, patterns of movement and numbers vary greatly from year to year in response to fluctuations in food supplies, especially in winter. The birds I saw had moved south because of a poor crop of mountain ash berries, conifer seeds, and seeds of other trees across much of Canada.

Breeding locations also depend on food supplies and vary from year to year, but nesting primarily occurs in the open spruce and fir forests of Canada. The male grosbeak sings soft, whistled notes to defend his territory and in courtship feeds his mate. He remains nearby while she gathers moss, twigs, grass, lichen, and rootlets to build a bulky nest fifteen to twenty feet high on a horizontal branch or in a fork of a conifer. She sits on her two to five eggs for about two weeks. Her mate feeds her on the nest. Both parents develop throat pouches in which they carry seeds, buds, berries, and some insects to their nestlings. Young birds fledge two to three weeks after hatching.

Because of their flocking nature, these birds may be vulnerable to the spread of disease. Habitat destruction from logging operations is another concern, as are poor food crops and competition with other species.

I will always connect the 1990 occurrence of pine grosbeaks in my woods to the three expert birders who came to see them, especially Ray Glassel, a beloved Minnesota birder who has since passed away. The birds remained among the cedar trees for six weeks, which was fortunate because they have not appeared in my woods again.

Nancy Overcott, illustrated by Dana Gardner, Fifty Uncommon Birds of the Upper Midwest

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