Providing bluebird houses has long been a favorite pastime in North America. Bluebirds are loved for their beautiful blue coloring, as well as, their gentle disposition and pleasing voice. The bluebird is the symbol of love and happiness in many of our songs.
Once a common bird, the bluebird was numerous even in urban residential areas, but it has seen a decline in numbers, with the Eastern Bluebird losing up to 90 percent of its population. A number of factors, such as insecticides, the destruction of their habitats, predators, and competition from other birds have contributed to this decline. The destruction of some of their food supply, such as the wild holly berries used in Christmas decorations, has also been a factor.
Those who love the bluebird have begun a massive effort to save it through the erection of thousands of nesting boxes appropriate for this species and predator- and competitor-proof. And the bluebird is beginning to reappear in areas where these bluebird houses are established.
There are three species of bluebird: Eastern, Western, and Mountain, and they belong to the thrush family. The Eastern Bluebird or Sialia sialis breeds in every state east of the Rocky Mountains. It is bright blue with a rusty red breast similar to the robin's. The Western Bluebird or Sialia currucoides breeds in the western states from Canada to Mexico and east to Colorado. It has a blue throat, and the red color extends to its upper back. The Mountain Bluebird or Sialia mexicana breeds in the Northwest, east to the Dakotas, and north into Alaska. It is entirely blue, with a white underbelly.
Bluebirds are primarily insectivores, eating many insects considered pests by man: cutworms, grasshoppers, and flying insects. They supplement this diet in fall and winter with wild berries and may starve if snow covers the ground and berries are unavailable.
The spring courtship rites of the bluebird are among the most enjoyable to witness. The male selects a suitable nesting cavity and devotes all his energy to luring a female to it with song. He sings and sings, as the female sits passively by, enjoying his effort. When she inspects the nesting place, he interprets her interest as acceptance and his song becomes even more passionate. But the final selection of the nesting place is hers, and if she finds his choice unacceptable, he must search for something better.
The female builds a nest of dry grass or pine needles and other plant material. The nest is typically about three to four inches deep. Here the Eastern Bluebird lays an average of three to five clear blue eggs though occasionally they may be white, with the western and mountain species adding one or two more. They hatch in two weeks and the baby birds leave the nest in 15 to 20 days, ready to fly and soon able to feed themselves. By fall the pair has raised two or three broods of young and may migrate south if their food supply runs out or it gets too cold.
The bluebird's chief competitors among other birds are the house sparrow, or English Sparrow, and the starling, both of which like the same type of nesting space. Sparrows will break the bluebird's eggs in a nest, or move into the nest during the winter when the bluebird has migrated. They will even peck the baby or adult birds to death, with the bluebird often unable to defend itself. Starlings will drive bluebirds out of an entire area and occupy every available nesting cavity, unless man intervenes.
We can assist in the return of this lovely bird by providing suitable habitats, winter shelter, and food supplies. Plants that bear berries throughout the winter (bittersweet, hackberry, dogwood, American holly, privet, bayberry, sumac, and others) will provide food for not only bluebirds but many other species. Winter roost boxes provide shelter in the coldest season for many birds. In areas where bluebirds find sufficient food, they may stay all year, but a roost box will allow them warmth on cold nights. And specially designed bluebird houses, with predator guards on the entrance to keep out squirrels, raccoons, and competing birds, will give the bluebird a safe place to live and rear its young. Nests of sparrows and other competitors must be cleaned out of the bluebird house on a regular basis.
People sometimes create a bluebird trail by hanging many bluebird houses in an area, about 100 yards apart, to give the bluebirds an abundance of housing. They are often placed on fence posts, giving the appearance of a trail. Tree swallows often find bluebird houses to their liking as well, and this problem can be lessened by hanging two houses back to back, even on a post or close to each other. Two bluebirds will not nest near each other, so this gives the swallows one house and the bluebirds the other. The swallows will even help protect the bluebirds from other competing birds.