Mary Margaret Schonhardt, age 12, of Pittsburgh, Pennsylvania, for her question:

Do wrens return to the same nests?

Certain wrens trust us enough to nest in a man made bird house, close to a human habitation. These are the bold little house wrens and sometimes the same family may return to occupy the same apartment. However, wrens build new nests every season. In fact, they rather outdo themselves. The male bird partially constructs several nests. The female selects the structure and location she prefers    and adds the finishing touches to the project.

North America is lucky to have a dozen or so wren species and subspecies. All of them are charming small birds and most of them can sing delightful songs. Though most of them are shy of people, they are rated among our friendly allies in the world of nature. For the wrens consume hordes of destructive caterpillars, beetles and other insect pests in our fields and gardens.

In the fall, most of them migrate to regions around the Gulf of Mexico or to Southern California and a few species travel as far south as Mexico. Several Southland species are permanent residents. Another year round resident has a very wide range, extending north of Pittsburgh. He is the Carolina wren, who wears a long white streak above each eye and lives a secretive life in swamps and wild woodlands. Here, there and almost everywhere, the friendliest species is the sassy little house wren. But come fall, he departs for regions around the Gulf of Mexico and perhaps even farther south.

In summer, the house wren's nesting range extends through most of the United States and north into Canada. The parents and perhaps their grown children tend to return to their old neighborhood. Some occupy suitable bird houses, others nest in tree holes near human homes. The male house wren arrives first and stakes his claim to several nesting sites. With sticks and twigs he builds half a dozen or so sloppy structures in tree houses and other suitable sites around the neighborhood.

When the female arrives about ten days later, she makes her selection. She may return to last year's site, or this may be taken by her grown children or by other local wrens. In any case, the male bird's sloppy work will not do. She demolishes it and builds a firm nest of twigs and grasses, lined with soft feathers. She may add a domed roof and a side entrance. Though the parents may return to the very same site, Mrs. Wren builds or rebuilds a new nest.

The eggs of the house wren are speckled with pinks and browns and there may be six, eight or even ten of them. In 12 to 14 days they hatch and the nest is crowded. The dark fuzzy chicks open their big yellow mouths and the parents stuff insects down their hungry throats. The noisy family does a lot of chattering. And sometimes the male bird bursts into a bubbling song, punctuated with stammers and lyrical trills. Like most of his cousins, the house wren is a talented singer.