Mary Van Vleck, Contributor
Directly opposite my house, about 40 feet away, are two bluebird boxes that bring me entertainment all year long. They are placed in a grassy area, away from trees, designed to attract eastern bluebirds rather than chickadees, house wrens or the pervasive house sparrows.
In the early spring I watch from my kitchen windows as various bluebird and tree swallow couples come to inspect these houses, competing among themselves in birdlike fashion, flying or diving at one another in threatening ways but seldom touching; or for a while, claiming the house as their own, they’ll sit on top of or inside it, preventing their competitors from entering.
Curious, I’d then watch as all the birds would fly off with no apparent indication as to who won out in the latest struggle for a house. Usually the swallows win rather than the bluebirds, and they take up residence in one of the two houses. Being swallows that need a certain amount of space, they will fiercely defend their territory—including the area around the second box—from other tree swallows, but they accept the presence of the bluebirds in the neighboring box. Each has its own niche, and they do not compete for food.
The antics and brilliant blues of both bird species keep me entertained most of the summer as they fly about, searching for food, and the male singing to declare his presence and to keep away all competitors. Once the eggs hatch, the parents spend every waking moment hunting and delivering food for their hungry, fast-growing chicks. Although most years both the swallow and bluebird young fledge successfully from their respective boxes, I have always missed the moment when the babies leave the nest. And then they are gone, leaving behind a quiet, empty house—until the parents return to start another brood. Bluebirds usually raise two to three broods a year.
In the early fall, tree swallows and later the bluebirds join flocks of one or more species, feeding together, until they fly south. However, some bluebirds remain in Vermont throughout the winter in small flocks of five to twenty birds. They can survive the cold as long as there is ample food. While bluebirds, like robins, depend largely on worms and insects in the warmer months, their diet changes during the winter from animal protein to fruit, primarily berries, and of those, primarily the fruit of native species. At this time of year most of our native shrubs, such as the prolific wetlands-loving winterberry and staghorn sumac, are loaded with berries. These shrubs, plus the red osier dogwood and some holly species, are especially effective shrubs that we can grow on our properties to attract and sustain our local birds.
The bluebirds in the fall and winter seem to come visit for a few days and then they disappear again, to other nearby properties, I assume, where the food supply may be more abundant, but then suddenly they are back—four or five of them together. I see flashes of brilliant blue on the males as they flock in the trees and around the old birdhouse, a few sitting on top, taking turns to inspect the interior. And then they’re off again.
In early December, I watched as a small group of bluebirds clustered around the birdhouse when a larger bird with a flashy white rump flew in and landed on top of the house, scattering the smaller birds. The white rump indicated that it was a northern flicker. With the flamboyant, self-confident manner typical of his woodpecker species, he peered over the front of the house toward the entrance hole, cocking his head from side to side as if to say, “Is this place big enough for me?”
Clearly the hole was too small, and seconds later the flicker flew off towards the trees, leaving the box once again for the bluebirds. Chances are good that the box interested them as a winter roosting site, for protection from the bitter cold and winds, especially at night. Bluebirds are known to cluster together inside a box in order to keep warm. However, I’ve never had proof that they used these particular boxes.
This is but one of the mini-dramas that I have observed from my window. Birds can be endlessly fascinating with their colorful bodies and beautiful songs, their nest building talents and extensive migrations and their amazing abilities to withstand our New England winters with their tiny bodies. (Have you ever held a chickadee in your hand?!) And we have so much more to learn about them!