TREECREEPERS: Certhiidae

PHYSICAL CHARACTERISTICS

Treecreepers are small, mostly brown birds that have long, slightly curved bills, long, slender tails with twelve stiff, pointed feathers, a narrow, teardrop-shaped body, and short legs with long toes and highly curved claws. They possess coloration that allows them to blend into their forest habitat in order to protect themselves from predators, animals that hunt them for food. Plumage (feathers) varies among species. However, upperparts are generally shades of brown with streaks of black, under parts are white or buff with shades of mostly rufous (reddish) or cinnamon, but sometimes of gray, and a stripe above the eye is buff or white. Males and females are similar in both size and color. In the first year, young birds have duller and streakier looking upperparts than adults, but look more like adults after the first year. Adults are 5 to 6 inches (12 to 15 centimeters) long.

GEOGRAPHIC RANGE

They range widely across the Northern Hemisphere, and in many areas of central and southwest Africa.

HABITAT

Treecreepers inhabit mature pine-oak woodlands and open pine forests. Depending on the species, treecreepers are found anywhere from sea level to mountainous regions and from temperate (mild) to tropical climates.

DIET

Treecreepers eat primarily small insects, spiders, and other small invertebrates. They use their thin bill to explore beneath the tree bark. During the winter, they also eat seeds and nuts, especially when other prey is scarce. Food is not normally stored for future use.

BEHAVIOR AND REPRODUCTION

All treecreepers, except for one species, use their tails to help them climb. Their short legs, long toes, and strong claws help them to cling tightly to the side of trees while foraging (searching for food). They forage singly, in pairs, and in flocks of many different bird species. Foraging rituals consist of flying to the base of a tree and then searching and probing under the bark for insects while climbing the trunk. They also look for food while clinging to the undersides of limbs, creeping outward from the trunk almost to the tip of the main branch. They climb in a jerky, spiral motion. Songs of treecreepers are quiet sounding trills, and calls are high-pitched and thin. Such sounds are used to establish and defend their breeding territory.

Most treecreepers construct nests under loose pieces of bark on dying or dead trees. Once in a while, treecreepers build nests on walls of buildings, in crevices (narrow cracks or openings) of trees, in heavy vegetation such as ivy, and within nesting boxes. Nests are built from 1.5 to 52 feet (0.5 to 16 meters) off the ground, with such a range of heights due to differences in species. Most females lay four to six white and faintly spotted red or reddish brown eggs. Females perform all of the incubation (sitting on eggs) duties, but both males and females feed their young. The brooding period (time to raise young together) is thirteen to seventeen days, with sometimes two broods each year. After the young are old enough to fly off, they will often remain as a family group for two to three weeks.

TREECREEPERS AND PEOPLE

There is no known significant relationship between treecreepers and people.

CONSERVATION STATUS

Treecreepers are not threatened, but some species have seen slight decreases in their populations.

BROWN CREEPER (Certhia americana): SPECIES ACCOUNT

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).

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. ∎

FOR MORE INFORMATION

Books:

Alsop, Fred J. III. Birds of North America. New York: DK, 2001.

Baughman, Mel M., ed. Reference Atlas to the Birds of North America. Washington, DC: National Geographic, 2003.

del Hoyo, Josep, Andrew Elliott, Jordi Sargatal, et al, eds. Handbook of the Birds of the World. Barcelona: Lynx Edicions, 1992.

Dickinson, Edward C., ed. The Howard and Moore Complete Checklist of the Birds of the World, 3rd ed. Princeton, NJ and Oxford, U.K.: Princeton University Press, 2003.

Field Guide to the Birds of North America, 4th ed. Washington, DC: National Geographic Society, 2002.

Harrison, Colin James Oliver. Birds of the World. London and New York: Dorling Kindersley, 1993.

Forshaw, Joseph, ed. Encyclopedia of Birds, 2nd ed. San Diego, CA: Academic Press, 1998.

Kaufman, Kenn, with collaboration of Rick and Nora Bowers and Lynn Hassler Kaufman. Birds of North America. New York: Houghton Mifflin, 2000.

Sibley, David. The Sibley Guide to Birds. New York: Alfred A. Knopf, 2000.

Terres, John K. The Audubon Society Encyclopedia of North American Birds. New York: Knopf, 1980.