Most of the birds that stick around Cabin John in winter have the dullest of plumage. Among the exceptions, there is of course the bold bon vivant, the Northern cardinal, decked out in vivid scarlet feathers. But a real treat is to see a gang of Eastern bluebirds flitting through the woods or along a field edge, reminding us that color vision is a miraculous gift we primates share with birds, even though somewhat underutilized for the dull tones of winter.
There is no better test of this color-vision privilege than to compare the black-and-white illustration of an Eastern bluebird that accompanies this article with the real thing on a snowy day, its radiant blue head and back feathers set off against an orange neck and throat and a white belly. If ever a bird seemed to be wearing a uniform, this would be the one. Western bluebirds and mountain bluebirds are lovely, too, living west of the Continental Divide, but I think ornithologists missed an opportunity by not giving the Eastern species a name such as the Brilliant bluebird as they did with the Resplendent quetzal.
Bluebirds are in the thrush family, and while their songs are far less melodic than the Wood thrush or Veery who visit our local forests in the spring and summer, or the now silent but visible Hermit thrush who winters here, they have plumage that must be the envy of the other thrushes, who tend to be spotted or a bit more reddish on the back or even a dull grey.
Colorful plumage in the winter might not seem like a great anti-predator strategy: in an environment of leafless trees and shrubs, it is much easier for a cruising Cooper’s hawk to spot a bluebird. But at this time of year, bluebirds stick together in groups. They have safety in numbers, and they warn each other about the presence of possible threats. Maryland might not seem like a great wintering spot. The insects are in diapause, eggs deposited under bark or nymphs resting underground, waiting for spring to arrive. And so the bluebirds shift to a fruit diet, and Maryland provides a smorgasbord assisted by thoughtful gardeners who plant native dogwood whose fruits are rich in nutrients to sustain overwintering birds. Wild grape, sumac, hackberry, dried raspberries, bayberries, Virginia creeper (a member of the grape family), eastern juniper—all fuel the bluebirds.
The Eastern Bluebird’s story is a perfect one to welcome in a new year with hope for better things to come. The species had made a remarkable comeback from the early part of the 20th century when it suffered a heavy toll due to the invasion of European starlings that took over their nest cavities, cowbirds that parasitized their nests, habitat loss, and pesticides. But by curtailing pesticides and placing nestboxes across rural America whose openings are suitable only for bluebirds, this beloved songster has come back. At the callous hand of many of us, bluebirds faced declines; in the respectful embrace of birders and nature lovers, bluebirds have made a resurgence that continues into this century and 2019.
In this shutdown season, there is no reason to be a shut-in. Why not go out and listen for its soft warbles and find our winter bluebirds? And when you find some, think good thoughts about the restorative gestures we can make for other species with whom we share this beautiful and colorful Earth.
By Eric Dinerstein
Illustration by Trudy Nicholson