Certhia americana

Preferred habitat includes forest, woodlands, forested floodplains and swamps. Scrub and parks are also used in winter and during migration. Most often found in coniferous and mixed forests. A study by Franzreb (1985) describes the habitat in Arizona as mixed-coniferous forest, dominated by Douglas-fir, ponderosa pine and southwestern white pine. Within the habitat, birds selected the largest (tallest) trees most often for foraging. Hejl (pers. comm.) reported finding larger numbers in western redcedar stands than in the Douglas-fir/ponderosa pine stands in 1992 field work.

In the eastern U.S. south of the northern conifer zone, populations occur regularly in forested floodplains, and sometimes swamps. Hamas (pers. comm.), based on his experience, suggested that floodplain forests may be important habitat in Michigan. Davis (1978) studied populations in Michigan in two different forest types. One was an old white cedar, balsam fir, and black spruce swamp, with components of sugar maple, red maple, white pine, basswood and paper birch. The other was more topographically varied and drier; tree species included red maple, American beech, with less common white oak, eastern hemlock, large-toothed aspen, butternut hickory, and American elm. In the wetter areas of this site, dead American elms were common, and in the wettest areas, white cedar and eastern hemlock occurred. Davis (1978) found that all nests were in dead trees, and all nest trees were near water. Two were in swamps, while all others were within 60 m of flowing streams.

A component of dead trees is essential for nesting, so brown creepers tend to be associated with older forests. Hejl and Woods (1991) found them in old growth forests (200+ yr), but never in rotation-aged (80 to 120 yr) Douglas- fir/ponderosa pine stands in western Montana and adjacent Idaho. The birds have also been known to move into areas where many trees have died due to flooding or disease (Bent 1948).

Temporary positive impacts have been created by Dutch elm and other forest diseases, and by artificial floodings in forested areas. Both diseases and floodings leave standing dead wood and create large numbers of good nesting sites. However, the suitability of the habitat is, of course, only temporary in these situations. Creepers have been reported to become abundant in such situations (Bent 1948, Davis 1978, Nicholson pers. comm.), suggesting a certain degree of opportunism. Forest, woodland, swamps; also scrub and parks in winter and migration. Negatively impacted by forest fragmentation in southern Wyoming (Keller and Anderson 1992).

Nests usually behind loose slab of bark still attached to living or dead tree, average of 1.5-5 m above ground (Harrison 1979). Also occasionally in knot holes when loose bark is not available (Bent 1948). One observer (Bent 1948) noted that nests were often under the only remaining piece of bark on a dead tree. Davis (1978) found that tree canopy was partially open at each nest site in a Michigan study.

Territories ranged from 2.3 to 6.4 ha in a study in Michigan (Davis 1978). Rough approximations of density, calculated from maps of nest locations at the study sites in Davis (1978) yielded these figures for three study sites: two ha per pair, and 1.5 ha per pair for two areas of swamp forest habitat; 5.6 ha per pair in a more upland site. In the latter area, nests were close to streams, so that the area of appropriate habitat may have been smaller than the overall study area, and 5.6 ha per pair may be exaggerated by the inclusion of inappropriate habitat away from streams.

Few observations of predators appear in the literature. One incidence of a creeper chased (but not captured) by a northern shrike is recounted in Bent (1948). Creepers are known to respond defensively to the scream of a hawk (Bent 1948, Davis 1978).

NON-BREEDING: Bent (1948) reported that creepers are quite solitary, but there have been reports of communal roosting and huddling in winter. Fledglings roost in a characteristic huddle (Davis 1978, Ryser 1985). They were reported to move in mixed-species flocks in the winter in Louisiana, Maryland, and in summer in Maine (Morse 1970). In Louisiana, they were nearly always observed in mixed-species flocks in winter rather than singly (Morse 1970).

Four to eight eggs, most commonly five or six, are laid (Bent 1948, Davis 1978). Incubation begins once the entire clutch is laid (Davis 1978). Incubation lasts 14 to 17 days, but 15 is apparently most common (Davis 1978). Young fledge in 15 to 16 days, and are fed by both parents for about two more weeks.

Davis (1978) found that 58% of nests with at least one egg or nestling (out of 19 observed) succeeded in fledging young. Survival rates, calculated from a total of 94 eggs laid were 60% from laying to hatching, and 94% from hatching to fledging, or 52% overall (from laying to fledging).