Last week I wrote about the rich variety of birds that are coming and going around my neighborhood, most of them in an area as small as 10 acres. I was quite excited to report that after two summers of waiting, I finally have a pair of bluebirds who moved into one of my nesting boxes. It seems like a good time to tell my seasonal tenant's story.
Eastern bluebirds are in the same family as American robins and thrushes (turdidae for all you scientific name sticklers), but they're very easy to distinguish from their cousins. The only other regional bird you can mistake for an eastern bluebird is an indigo bunting. Eastern bluebirds are larger and less intensely blue than the buntings, and they have a rust-colored breast like a robin. Females are a grayish-blue color and usually can be found in the vicinity of their bright blue mates. They live year-round in much of the eastern U.S; here in the Northland they move in for the summer shortly after their American robin relatives. I've observed them in mid-March during a mild spring and not until well into April if cold weather lingers.
Eastern bluebirds can usually be seen in open country including meadows, farm fields and scrubland. They also like forest openings and golf courses. They're a common power line percher and you'll often see them dropping from a wire or fencepost to pounce on insects on the ground. They also eat a lot of fruit in the fall and winter. They have a warbling, chattering song and a quiet but distinctive "tu-a-wee" call. Both sexes sing and chatter at predators. Eastern bluebirds are quite different in their nesting habits from the other thrushes. They're cavity nesters, and prior to the human invention of birdhouses they lived entirely in natural cavities such as woodpecker holes. This is one species whose intersection with humans has helped them thrive. Eastern bluebird populations fell throughout much of the 20th century due to competition for natural nesting holes from introduced species like European starlings. Starting in the 1960s, public efforts to establish nesting boxes has led to a steady increase in bluebird numbers. The male bluebird courts his mate by bringing nesting materials in and out of the nesting hole while fluttering his wings attractively. This is all a show, however; the female ends up building the nest and incubating the eggs by herself. The joke may be on her mate. While bluebirds usually are pair bonded for several seasons, studies show that about one in four bluebird eggs has a different father than the mother's main squeeze.
Bluebird houses, and instructions to build your own, are easy to come by at hardware or farm stores and on the Internet. Just be sure that the hole is large enough to keep out starlings. Try to place them in an open area that isn't hemmed in by houses or trees. Eastern bluebirds usually have a couple of broods per year, so don't worry if you don't see any around in the spring. And if they don't move in yet, you've still provided important nesting habitat for other species such as chickadees, great crested flycatchers and tree swallows. Friend of the column Jean in Lake Namekagon reports she had six baby chickadees in a nesting box that recently fledged, and I agree that all successful bird families are a reason for joy.
Another reader, Mark from Ashland, enjoyed hearing about catbirds and has a new pair nesting in some Virginia creeper outside the bedroom window. His catbird is bolder than mine. Mark shared a delightful passage from the 1955 edition of "A Natural History of American Birds of Eastern and Central North America" by Edward Forbush: “The catbird is a busybody. He is consumed with curiosity. Let anyone but imitate the scream of a frightened or wounded bird, and all the catbirds in the neighborhood will appear in full cry….The bird’s moods are many. It is in turn a merry jester, a fine musician, a mocking sprite and a screaming termagant — but always an interesting study.” Indeed. Thanks for sharing and keep the correspondence coming to email@example.com.