A plump traveler with a rich song
By Susan Campbell
’Tis the season for unusual travelers! Have you spotted an odd, plump songbird with a heavy bill and a blueish wash at your sunflower seeds? It just might be a blue grosbeak. This medium-size songbird can be seen along fence rows and on electric wires in rural areas throughout much of our state during the warmer months. Reappearing after long winter stays in Central America and the Caribbean, blue grosbeaks breed across much of the United States, from central California across throughout the Plains states and up into Virginia. And juveniles, less colorful than their parents, headed southward are even more likely to be overlooked.
Although this bird is found in all of North Carolina during the breeding season, it is often missed by casual observers during migration. The combination of black, brown, white and just a wash of blue of youngsters is confusing for certain. Furthermore, this is a bird of both pine and mixed forest, one often encountered with so many other birds along habitat edges that are associated with agricultural land use. However, the blue grosbeak’s large silvery bill is easily recognizable. The sexes are significantly different with immature birds having indistinct plumage similar to their mothers; Males are a dark blue with a small black mask around the bill and eyes as well as chestnut wing bars. Females are a cinnamon hue with rusty wing bars and a bit of blue on the rump and in the tail. Some males in their first spring will not breed. If they do not have the extensive blue of fully mature males, then they will not be able to attract mates in order to start a family. However, this year of singing, fighting and extensive experience foraging will make them very good prospects come their second spring as long as they survive the winter.
The blue grosbeak’s song is a rich warble, but its call is a loud, metallic “chip” that carries a long way regardless the season. Hearing these vocalizations is the best way to find them, given their propensity for spending a lot of time in thick undergrowth. Nests are placed low in thick vegetation and viny tangles; the blue grosbeak prefers shrubbery to trees for breeding. The nest is a compact, cup-shaped affair composed of twigs, grasses, leaves and rootlets often with paper, string or other litter mixed in. Blue grosbeaks are one of only a few migrant species that raise not just one, but two broods of between three and five young in a season.
Unfortunately, blue grosbeaks all too often end up, unwittingly, raising the young of parasitic brown-headed cowbirds. Cowbird females lay eggs in the nests of other species found in open or semi-open habitat. The eggs, which are larger, manage to hatch ahead of the hosts.’ They produce young that then grow larger and faster, out-competing the nestling grosbeaks.
Like most of our songbirds, this species feeds heavily on insects in the summer months. Caterpillars make up a significant portion of the diet. But blue grosbeaks also will hunt for food at or near ground level, collecting adult grasshoppers and crickets as well as other large insects. Their bills are effective at breaking up prey items as well as large seeds, such as sunflower kernels. Individual blue grosbeaks do show up at feeding stations, but they do not congregate the way other finches do. So keep an eye out if you live on the edge of town or in a more rural location. Spotting one of these distinctive birds is more likely now than ever — especially at feeders: quite a late-season treat.
Susan would love to receive your wildlife sightings and photos at email@example.com.