Evening Grosbeaks

by Linda de Kort
linda@westvalleynaturalists.org

We saw Evening Grosbeaks outside our kitchen window on this cool fall morning.

The first time I spotted a flock of Evening Grosbeaks at our feeder I thought that I was witnessing escapees from a tropical bird aviary. The plumage of these stocky robin-sized birds is stunning and unmistakable. The male’s forehead and eyebrows are bright yellow. The crown is black and the breast and lower back are also yellow. Most of the wing is black with a striking white patch. The stubby notched tail is totally black. Our neighbor, Reta Sweeney, describes these dapper males as “the birds in backwards yellow trimmed tuxedos.” Females and immature males are duller, but are easily identified also by the white wing patches and the large bill. The females also have much white at the tip of their short black tails and white spots on the upper tail. The name of this bird is a misnomer. Apparently the first recorded sighting in 1823 of this heavy billed species occurred “at twilight”, hence the name: evening grosbeak (Coccothraustes vespertinus). These birds are actually more active in the morning and will often roost for the night as early as 2 pm in the winter.
Male Evening Grosbeak (photo by Frank de Kort)
Female Evening Grosbeak (photo by Frank de Kort)

They are aptly named grosbeaks, having an unusually bulky bill whose color differs in summer (slightly greenish) and winter (bone colored). This powerful triangular bill is fashioned specifically for cracking seeds, which they first roll up on edge with their tongues, then pop in two with a munch of their heavy mandibles. They especially are attracted in the early summer to black oil sunflower seeds.

Male and Female with bright green beaks at black oil sunflower seed feeder in summer (photo by Frank de Kort)

The food of the evening grosbeak also includes spruce budworm larvae and other insects. As is common with birds breeding at high altitudes, the Evening Grosbeak usually only lays one brood of 2-5 eggs per year. The nests are often high in a tree and difficult to spot; courtship also is a bit secretive with no showy display or song. The nest looks like a flattened loose saucer of small twigs and roots, lined with grasses, twigs, lichens, or conifer needles. The eggs are light blue to blue-green with brown scrawls concentrated on the large end. Nesting dates in NW Montana are early June to late July. When the fledglings emerge by late July, you know that they are here with much raucous rattling and buzzing.

Evening Grosbeaks range throughout the northern US and southern provinces of Canada. They are found in the mountains of the Western US, Canada and Central Mexico. If food is available they may not migrate. We have seen Evening Grosbeaks on our Christmas Bird Counts in this valley for the last decade. Evening Grosbeaks are not doing so well nationwide, however. The decline of the Evening Grosbeak in the US has been startling: 78 percent in 40 years. Because they are birds of boreal and montane forests, they are susceptible to all incursions into those habitats: logging, mining, drilling, acid rain, and human development. There are many actions we can take to help Evening Grosbeak populations rebound. One of them is to plant Rocky Mountain Juniper which is a native shrub and provides good cover for many songbirds, including Evening Grosbeaks. Another is to stay involved in the monitoring of our local birds through citizen science efforts such as Christmas Bird Count, Backyard Bird Count, and Project Feeder Watch. You can learn more about local bird species and how to how to get involved in bird monitoring by visiting https://www.flatheadaudubon.org

“Why I am called a GROSbeak!”

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