By Eileen Dowd Stukel

Click here for photo

Outside my kitchen window is a tall honeylocust tree. It’s not much to look at, but it provides summer shade and its limbs support bird feeders. Every once in awhile, especially during fall or winter, a glance out the window reveals what appears to be a piece of bark working its way methodically up the tree trunk. This special sight is a brown creeper, a rare breeding bird of South Dakota, but a more common migrant and winter visitor.

The brown creeper looks unlike any other North American bird. It is sometimes called the American treecreeper, an allusion to its relationship to other members of the Family Certhiidae, the treecreepers. The brown creeper is the only member of this family in North America. Its primary breeding range includes portions of Canada and Alaska, northwestern and many western states as far east as western Montana and western Wyoming, with breeding season records or observations in many additional states and Mexico. In South Dakota, brown creepers are mostly known from the Black Hills, a breeding population thought to be isolated from others.

The brown creeper’s cryptic coloration and quiet manner cause it to be overlooked by many bird-watchers. Its habits may remind us of other birds, such as woodpeckers and nuthatches, but closer inspection reveals its uniqueness. The mottled, brownish back blends in perfectly with the tree bark background. A long decurved allows probing for insects behind bark and within cracks and crevices. Its specialized tail resembles a woodpecker’s tail. The relatively long tail has 12 stiff and pointed feathers, with projecting feather shafts to aid the creeper in propping itself against a tree trunk.

Nearly all of the perching songbirds familiar to us are called passerines—members of the Order Passeriformes. All passerine birds except the tree creeper molt their tail feathers in a centrifugal pattern, meaning from the center outward. Treecreepers keep their central tail feathers intact until all other tail feathers are replaced. This molt pattern allows the tail to provide climbing support as long as possible. This molt strategy is similar to that of woodpeckers, another group of birds dependant on the tail for propping against tree trunks and limbs.

The brown creeper’s breeding habitat is typically a dense, mature forest, which may be coniferous (ponderosa pine or white spruce), deciduous (bur oak or sugar maple-basswood), or a mixture. The species often nests in wet areas, such as flooded forests, swamps, or boggy sites, possibly because of the presence of trees killed by flooding. Such dead or dying trees may have large, peeling bark layers, which the brown creeper selects for its nest site.

For many years, the brown creeper was considered solely a cavity nester. Naturalists examined many woodpecker holes in search of brown creeper nests. After learning where European and Asian treecreeper species nest, North American biologists more easily located brown creeper nests by searching behind loose bark. Using materials gathered by the male, the female builds a nest foundation of twigs and bark chips, attaching what will become a crescent-shaped nest with supportive twigs that typically secure the nest to the bark rather than to the tree trunk. The female the builds a softer inner layer of finer shredded bark, moss, ferns, hair and feathers.

The female lays 4 to 9 eggs in her single annual brood. The male feeds her as she incubates the eggs for 14 to 17 days. After hatching, young remain in the nest for another two weeks, being fed by both parents. The adult pair and fledged young may stay together temporarily as a family group as the young learn their parents’ feeding style. The brown creeper’s typical foraging habit is to fly to the bottom of a tree and work its way up in a spiral pattern, probing and extracting along the way, then flying to the bottom of a nearby tree to start again. After fledging, siblings may roost together at night with their heads facing inward, selecting a new roost site each night. Adults may sometimes roost in cavities with others, but they typically roost alone.

The family Certhiidae is closely related to the families containing chickadees and nuthatches, birds that often cache (store) food for later consumption. Although brown creepers often travel in foraging flocks with chickadees and nuthatches, they almost never follow their food-caching example. However, during a recent study near Rochester, New York, scientists Steven Lima and Robert Lee observed brown creepers caching bits of sunflower seeds in crevices of red pine trees. The authors speculated that this habit might be derived from ancestors common to chickadees, nuthatches, and treecreepers. Alternatively, recent DNA analyses indicate that treecreepers perhaps should be grouped within a larger family containing wrens, gnatcatchers, and gnatwrens.

The brown creeper pays no heed to debates about its origin or proper biological classification as it probes for insects and spiders, many of which are inaccessible to other birds of the forest. Dayton Stoner made this remark about the brown creeper in 1932: "Most of the insects taken are highly destructive; and many of them and their eggs, and immature wwws as well, are so small as to be overlooked by the majority of arboreal birds. That this bird is a valuable ally of the forester and horticulturist cannot be doubted."

This species is mostly solitary, although pairs may travel together. Migration and winter habitats are often more diverse than areas selected by breeding birds. Nonbreeding habitats include deciduous woodlands, parks, cemeteries, and suburban neighborhoods.

The brown creeper is considered a fairly common breeding bird in most of its breeding range, but an uncommon South Dakota breeding bird. Since 1988, only three nests have been confirmed in the Black Hills of South Dakota.

In addition to nesting under loose bark and less commonly in tree cavities, brown creepers sometimes nest in artificial sites. In 1971, several bird watchers described an interesting nest in a gap in the siding of a garage south of Rochford. The observers could see four nestlings, but only two birds fledged. They examined the nest more closely to find five dead nestlings very tightly packed in the bottom of the nest, birds that apparently died from starvation or suffocation as a result of being overcrowded. Whether this is a typical occurrence is unknown.