Certhia americana
brown creeper
(Also: American treecreeper)

Brown creepers (Certhia americana) are the only treecreepers in North America. They are found throughout North America from Canada and Alaska to as far south as northern Nicaragua. In Alaska and Canada, brown creepers generally breed along the coast. In British Columbia, brown creepers breed along the western coast and through the central and southern interior. Limited surveys have been done to determine the northern limits of brown creepers. In the western United States, brown creepers are found throughout forested areas of the Rocky Mountains in western Washington, Oregon and the northern mountains of California.

Brown creepers are year-round residents throughout much of their range. However, brown creepers that breed in the northern part of the geographic range migrate south for the winter. Brown creepers winter throughout most of the United States except for high mountain regions, the Great Basin, Sonoran Desert, southern Texas and Florida. (Hejl, et al., 2002)

Brown creepers live in coniferous forests and mixed coniferous-deciduous forests. They require large trees (dead or alive) for foraging and nesting. In the Pacific Northwest, brown creepers also live in coniferous forests but avoid the forests of the Olympics where trees are much larger and more spread apart. In the Rocky Mountains, brown creepers are found more in older red cedars, spruce-fir, and mixed conifer rather than in younger forests. (Hejl, et al., 2002)

Brown creepers are tiny birds with mottled feathers that make them nearly indistinguishable from a piece of bark when viewed at a distance. They have dark-brown upperparts that are heavily streaked with white on the head, back, scapulars (feathers covering the shoulder), and wings. They have a distinctive brown stripe through their eye and a white stripe above it. The underparts are white with red/brown lightly mixed in. They have a long, stiff tail with feathers that are used as props to help the birds move up and around the trunk of a tree.

Brown creepers are 11.7 to 13.5 cm long and weigh 7.2 to 9.9 g. Their wing chords measure 62.9 to 65.5 mm. A standard metabolic rate for brown creepers was measured at 4.0 kcal/24 hours.

Male and female brown creepers are very similar in appearance. Their decurved bills are one of the only ways to differentiate between the sexes. Males tend to have a slightly longer bill (1 to 2 mm longer) than females. (Hejl, et al., 2002; Robbins, et al., 1966)

Brown creepers are monogamous. Males sing to attract a mate. The pair then chases one another, rapidly fluttering their wings and exposing their white undersides. Courtship feeding (where the male feeds the female) occurs throughout the nesting cycle until the eggs have hatched. Breeding pairs remain together up to several weeks after their chicks are ready to fly. (Ehrlich, et al., 1988; Hejl, et al., 2002)

Brown creepers generally begin breeding in April, with breeding season peaking in May, June and July. Incubation in Michigan has been recorded as early as May 20.

The male and female chose the nest site together, but the female builds the nest. Nests are almost always built between the trunk and a loose piece of bark on a dead or dying tree. However, nests are occasionally found in locations such as inside a stack of concrete blocks and under loosened roof shingles. Nests take 6 to 30 days to build and are lined with feathers and bark.

The female lays 3 to 7 eggs and begins incubation after the last egg is laid. Incubation lasts 13 to 17 days. The female does all of the incubation and the male brings food to her.

The altricial chicks all hatch on the same day. The female broods them during bad weather, and both parents feed them. They fledge after 15 to 17 days, but continue to be fed by the parents for at least two weeks.

Data on the exact age of first breeding and intervals between breeding are scarce, although it is believed that breeding occurs in the first year. (Ehrlich, et al., 1988; Hejl, et al., 2002)

Both parents search for a nest site, but the female builds the nest. The female does all of the incubation and brooding, during which the male feeds her. Both parents feed the chicks during the nestling and fledgling stages, before they become independent. Both adults also carry eggshells and fecal sacs away from the nest. (Hejl, et al., 2002)

The maximum recorded age for a banded brown creeper was 4 years, 7 months. However, little is actually known about the lifespan/longevity of brown creepers. (Hejl, et al., 2002)

Brown creepers usually fly short distances between tree trunks. They begin foraging at the bottom of a tree and when they reach the top they fly to the bottom of the next tree and begin again. They are territorial during the breeding season, but join mixed-species foraging flocks in the winter. They may also roost with other brown creepers in the winter.

Brown creepers are year-round residents throughout much of their range. However, those populations at high latitudes and northern longitudes migrate south in autumn. (Ehrlich, et al., 1988; Hejl, et al., 2002)

Family groups have been seen within a 500 meter radius of former nests. Territory size depends largely on the breeding density of a population. (Hejl, et al., 2002)

Brown creepers communicate primarily using vocalizations. When fighting for a territory, males sing a high pitched song. Vocalizations by males can be heard during the breeding season. The sounds are high and thin and vary within populations. (Hejl, et al., 2002)

Brown creepers primarily eat small arthropods such as spiders, psudoscorpions, and insects. Some insects they are known to eat include stinkbugs, fruit flies, and weevils. Brown creepers also eat seeds and other vegetable matter during the winter.

Brown creepers forage on live tree trunks and occasionally on large branches, but rarely on the ground. Large trees with thick bark tend to have larger densities of arthropods, and are therefor favored. Brown creepers probe tree trunks with their long curved bill. They move upward on the trunk, sometimes spiraling around it, working up the tree to within 1 to 3 m of the top. They then fly to the bottom of the trunk (or the trunk of another tree) and start over. (Hejl, et al., 2002)

Predators of brown creeper eggs, nestlings and adults include red squirrels (Tamiasciurus hudsonicus), domestic cats (Felis silvestris), northern flying squirrels (Glaucomys sabrinus), golden-mantled ground squirrels (Spermophilus lateralis), wood rats (genus Neotoma), and deer mice (Peromyscus maniculatus). Adults respond by freezing and flattening their bodies against a tree trunk. (Ehrlich, et al., 1988; Hejl, et al., 2002)

Brown creepers interact with other birds such as red-headed woodpeckers (Melanerpes erythrocephalus). Interactions can become hostile during territory establishment. Brown creepers compete for territories as well as food. They are also occasional hosts for parasitic brown-headed cowbirds (Molothrus ater). (Ehrlich, et al., 1988; Hejl, et al., 2002)

As insectivores, brown creepers may help to control pest populations.

There are no known adverse affects of brown creepers on humans.

Brown creepers are listed as a species of least concern by the IUCN. They are not protected under CITES or the U.S. Endangered Species act. However, they are endangered in Kentucky, threatened in Illinois, of special concern in Indiana, New Jersey, and Ohio, and protected in Idaho, Montana, and New York. Brown creepers are also protected under the US Migratory Bird Treaty Act.

The global population of brown creepers in estimated at 5,400,000 individuals. Population trends and causes of mortality of brown creepers are not well studied. (Hejl, et al., 2002)