The evening grosbeak is one of the most beloved birds in Maine and of the most enigmatic. These chunky finches are gorgeous: the yellow, black and white of the males suggests a goldfinch on steroids. Females swap out the yellow for a blue-gray color, yielding a more subtle beauty.

Evening grosbeaks are members of finch family and belong to the group known as the northern finches. Many of these birds nest to our north in the boreal forest or even the tundra. Winter conditions occasionally force these birds to move south in search of food. When that happens, Maine can be hopping with pine siskins, crossbills or evening grosbeaks.

Although evening grosbeaks nest in Maine, we mainly see them in the winter as the population swells from northern birds pushed south.

This winter has turned out to be one of the best years in memory for evening grosbeaks in Maine. Most of the 22 Maine Christmas Bird Counts found evening grosbeaks. Presque Isle took high honors with 154 grosbeaks, barely nudging out the 151 sighted in Unity. Orono, Ellsworth and Hartland all had over 50 individuals.

Despite the invasion, most birders have not been lucky enough to see them. This species is highly nomadic, with flocks seldom staying in one place for very long. They do love sunflower seeds, so feeders are attractive. The voracious appetites of these birds can put a dent in the budget of people that try to keep these gluttons fed.

It’s worth familiarizing yourself with the flight call of evening grosbeaks. The loud, mechanical “clee-ip” sound is distinctive. I hear far more evening grosbeaks than I see.

The original range of evening grosbeaks was in the coniferous forests of western North America. The species spread eastward during the latter part of the 19th century. The first record of evening grosbeak in Maine was an incursion in the winter of 1889-1890. The species was not found again in Maine for 19 years.

The movement east is thought to have been facilitated by the planting of non-native ornamental trees, especially box elder, that provide seeds for the grosbeaks. Caterpillar abundance, especially spruce budworm, plays an important role in the abundance of evening grosbeaks here in Maine. In particular, spruce budworms go through boom-and-bust cycles.

Although we think of finches as seedeaters, finches need to feed their nestlings more protein-rich food like caterpillars. So, when spruce budworms are abundant, nesting success of evening grosbeaks is high.

Peak numbers of evening grosbeaks in the northeast occurred from the 1960s into the 1990s when spruce budworm outbreaks were frequent. I remember large flocks of evening grosbeaks in the winters in North Carolina during the 1960s, a sign that abundance was high.

Alas, evening grosbeak populations have been declining since the turn of the century. The explanation for these declines is complex but certainly the lack of any spruce budworm outbreaks since 2000 played a role.

Field work for the Maine Breeding Bird Atlas shows scattered confirmed or probable evidence of nesting in the southern half of the state. However, most of the confirmed or probable records are in the boreal forests in the northern third of the state.

The name grosbeak, derived from the French for big beak, is certainly apt for evening grosbeaks. However, use of the name grosbeak can cause taxonomic confusion. We have four grosbeaks in Maine: the evening grosbeak, pine grosbeak, rose-breasted grosbeak, and the uncommon vagrant blue grosbeak.

Evening grosbeak and pine grosbeak are both members of the finch family. However, they are not that closely related. The closest relatives of the pine grosbeak are house finches and purple finches. Rose-breasted grosbeaks and blue grosbeaks are members of a different family altogether, the cardinal family.

Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu

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