Treecreepers: Certhiidae

Physical characteristics: Brown creepers vary in plumage within different populations. They generally have dark brownish upperparts that are spotted and streaked with white, buff, or pale gray, cinnamon rump and undertail coverts (small feathers around base of quill), white to buff under parts, pale eyebrows, and a rusty base on the long tail that contains stiff pointed feathers at the end. There is a bold, buffy band on the wings that is noticeable above and below during flight. Wings are also edged and tipped with buff and white. The bill of the brown creeper is thin and curved, and its claws are sharp. Western populations are relatively small, dark, and long-billed, while eastern populations are slightly larger, paler, and shorter-billed. The isolated population in Central America is darker and smaller than the northern population. Females and males look alike, and most juveniles look very much like adults. Brown creepers are about 5.25 inches (13.4 centimeters) long, with a wing span of 7 to 8 inches (17.8 to 20.3 centimeters) and a weight of about 0.29 ounces (8.4 grams).

To hide from predators, brown creepers hold their body against a tree, spread their wings and tail, and remain motionless. Their coloration blends in with the tree bark. (Ilustration by Michelle Meneghini. Reproduced by permission.)

Geographic range: Brown creepers range through North America (western and central Canada and most of the United States) and Central America (south to Nicaragua). Northern populations winter in southeastern United States and northern Mexico.

Habitat: Brown creepers live in mature coniferous, deciduous, mixed (coniferous/deciduous), or swampy forests and woodlands. They are usually located in lowlands.

Diet: Brown creepers forage by flying to the base of a tree. They are adapted for climbing ("creeping") on tree trunks and large branches in search for food with the use of their stiff tail that is placed against the bark for both support and balance. They also use their strong toes and claws for grabbing onto tree bark. The birds search and probe within bark crevices with their bill for insects while climbing either in a spiraling (like ascending a spiral staircase) or in a somewhat straight path up the trunk and large tree branches. They eat spiders, insects, larvae (LAR-vee), and other invertebrates, along with seeds and nuts. Once reaching the top of the tree, they fly down to the base of the next tree to repeat their foraging technique. Brown creepers are unable to climb head down, which is most likely why they fly from the top of previously foraged trees to the base of its next tree to be searched.

Behavior and reproduction: Brown creepers are usually not seen when observers are looking at trees, because their coloration is so similar to that of the tree bark. To hide from predators, they hold their body against a tree, spread their wings and tail, and remain motionless. They are generally solitary birds, but may join flocks of nuthatches, titmice, warblers, chickadees, and other small birds in the winter (during the nonbreeding season). Brown creepers are unable to move sideways or upside down. Their direct flights are usually of short duration, using rapid shallow beats of their wings. Their call is a high, reedy "tseeeee." Eastern birds have a call that is a very high, thin, quavering "seee" or "sreee," while the western birds' call is a buzz-like, often doubled "teesee." Their song is a thin, high series of quickly sounding notes "tee see see, teesyew, seee" (but the pattern may vary). For instance, eastern populations may begin singing with two long, high notes followed by an irregular low note "seee sooo sideeda sidio," while the song of western birds generally ends on a high note "seee sitsweeda sowit-see."

Before breeding, they build pocket-shaped nests of bark flakes, plant fibers, twigs, conifer needles, mosses, and silks, which are placed behind loose sheets of bark, in a split-out tree, or behind a heavy growth of ivy. Nests are lined inside with feathers and shredded bark. Monogamous (muh-NAH-guh-mus) partners (having one mate) build nests usually 5 to 50 feet (1.5 to 15 meters) above the ground. The nest is built away from other nests and birds. Females lay four to eight eggs, which are lightly flecked with reddish brown. The incubation period is thirteen to seventeen days, which is performed only by the female. The nestling period (time period necessary to take care of young before ready to fly off) is thirteen to sixteen days. Both parents feed the young birds, with only one brood per year.

Brown creepers and people: People enjoy putting out a mixture of nuts, peanut butter, suet, and cornmeal in feeders for brown creepers and watching them feed.

Conservation status: It is believed that brown creepers are declining in numbers, but so far they are not threatened. Their nesting areas are declining due to the cutting down of forest habitats. ∎