Many people have asked recently about a little brown mottled bird with a white breast and a curved beak that they have seen circling around the trunks of their trees. The bird is a brown creeper, a fairly common resident in our woodlands. Why they have become so obvious recently probably has several causes.
During the summer nesting season, brown creepers are shy and choose thick, dark pine woods in which to nest and therefore are not as easily seen. In winter they tend to become more sociable and often travel with wintering flocks of chickadees, nuthatches and juncos. They are primarily insect eaters and therefore will not actually visit your feeder with other birds but will usually be somewhere nearby busily circling the trunks of your trees, meticulously searching for dormant insects, insect eggs or scale insects in cracks and crannies in the bark.
Another possibility as to what has prompted so many recent sightings is that there has been a small migration through the area. These birds nest quite frequently at the higher altitudes in the coniferous forests. In Colorado it has been known to nest at nearly 11,000 feet, almost at timberline — although they nest more commonly at lower elevations of the spruce-fir forest. In winter they descend to areas of the transition zone, stream bottoms and occasionally even out on the plains. The young also stay with the parents and are fed for some time after they start moving about; therefore, the recent sightings could be small family groups traveling together to lower wintering grounds. Or the appearance of so many brown creepers in October could have been a typical north-south migration of birds from much farther north moving through in small numbers as they search for warmer winter locations.
The most characteristic trait of a brown creeper is its habit of climbing up a tree, usually in a spiral, appearing and then disappearing on the back side of the tree until they reach too many thick branches. At this point, it will fly and drop down to the base of a nearby tree and repeat the upward spirals. Almost all of the creepers’ food is insects. Among the many insects they are known to eat are aphids, moths, caterpillars, eggs of insects, scale insects, spiders, etc. Most of these insects are harmful to trees; therefore, brown creepers are highly beneficial to our forests.
Brown creepers build their nests under a loose flap of bark. If such a site cannot be found, they will use a rotted-out knothole or an old abandoned woodpecker hole. They cannot make their own cavity as woodpeckers do, for their beak is not made for chiseling. It is instead long, curved and delicate, designed for prying insects out of the cracks and crevices in bark.
They lay anywhere from four to nine eggs, although four to seven is more common. The young are naked when born and take quite a long while to feather out and mature, although they are sometimes seen creeping about the tree near the nest before they actually fledge.
Creepers have also been known to roost together at night in hollow limbs or other sheltered places. This would conserve their body heat, making it possible for them to survive in colder areas where they are known to winter. Brown creepers are an interesting part of our coniferous forests.