GOOD BIRDING

Bluebirds socially monogamous, except for their dalliances

Posted June 27, 2014, at 7:12 a.m.
While bluebirds found in Maine typically are orange underneath, the mountain bluebird like this one photographed in Colorado in April is completely blue.
Bob Duchesne
While bluebirds found in Maine typically are orange underneath, the mountain bluebird like this one photographed in Colorado in April is completely blue.

Bluebirds make people smile. They really are the bluebirds of happiness. But surely it must be more than the color that pleases people.

I’ll venture a few guesses. Bluebirds are residents of open areas such as meadows, parks, golf courses and blueberry fields. Unlike secretive birds of the forest and marshes, they perch in the open and are comfortable around people. They are chirpy, seemingly cheerful. They appreciate the bird houses we make for them and relish the occasional morsels we leave for them.

Bluebirds remind us of our bucolic past. They were a constant on the farms of our forebears until imported city birds started pushing them out. Bluebirds nest in cavities but so do starlings and house sparrows. These invaders were introduced from Europe, and as their populations grew, they stole away the nest sites favored by bluebirds. At the same time, suburbia devoured farmland. Old trees riddled with woodpecker holes were removed from the landscape. Bluebirds declined, and we missed having them around.

In the 1960s, efforts to save the bluebird began to flourish. Bluebird boxes were erected, often along organized bluebird “trails.” In 1978, the North American Bluebird Society was founded. Its publications preached nest cavity conservation and proper birdhouse construction. There is even an annual convention of bluebird lovers.

Enthusiasts also learned more about the proper building and placement of bluebird boxes. For instance, a one and a half inch hole is big enough for bluebirds but small enough to keep starlings out. Bluebirds don’t require perches on the bird house, and house sparrows are dismayed by the lack of a perch. Boxes should be on smooth metal poles at least five feet high to discourage predators. The entrance should face away from prevailing winds and sun exposure. Information such as this is readily available just about everywhere.

The density of box placement also is a curiosity. Bluebirds are territorial and will not nest within a hundred yards of each other. But they will tolerate other cavity nesters such as tree swallows and house wrens. Boxes placed closer together than a hundred yards can expect only one bluebird family to move in, but other species may nest closer. In the west, boxes should be placed even farther apart because the other two species of bluebird require bigger territories.

Wait. What? Yes, there are three species of bluebird in North America. We are familiar with eastern bluebirds, which are blue above and orange below. The western bluebird is similar, but its throat is blue rather than orange. However, nothing puts the blue in bluebird such as a mountain bluebird. This denizen of the Rockies is blue all over. Its habits also are distinct from its eastern and western brethren. Most bluebirds swoop through fields and drop onto the ground to capture insects. The mountain bluebird is more apt to hover and to pounce on insects from perches. It even forms small flocks in winter.

Bluebirds are members of the thrush family, closely related to American robins. At one time, they were as numerous as robins. Bluebirds are mostly insectivorous but can subsist on fruit and berries during the colder months. Eastern bluebirds migrate, though usually not far. Some even winter in Maine. The rest return in early spring, well before most other songbirds. A bluebird in April is no surprise.

Bluebirds are socially monogamous but do fool around. DNA studies show that an average of one in five eggs in the nest is the result of a quickie on the side. During courtship, males bring nesting materials to the cavities, but it is the female that makes the final choice of site and builds the nest. Both parents help raise the young, and they are apt to raise two broods each summer.

Many people wonder how to attract bluebirds to their neighborhoods. Unless there is sufficient open area, preferably with short grass ground cover, the birds will choose to nest elsewhere. If good habitat is available, the next obvious step is to erect bluebird boxes.

If you’re interested in attracting bluebirds, they find mealworms to be irresistible. Mealworms are the larval form of the darkling beetle and are available at many bird supply stores. Put some live mealworms in a platform feeder with straight, slick sides to keep them from crawling out. Dried mealworms are available, too, but bluebirds much prefer them alive and wriggling. Live mealworms keep for a long time when stored in the produce bin of your refrigerator. Still interested?

Bob Duchesne serves as a Maine Audubon trustee and vice president of its Penobscot Valley Chapter. Bob developed the Maine Birding Trail, with information at mainebirdingtrail.com. Bob can be reached at duchesne@midmaine.com.

 

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