- 4.7–5.5 in
- 6.7–7.9 in
- 0.2–0.4 oz
- Smaller than a White-breasted Nuthatch; larger than a Golden-crowned Kinglet.
- Grimpereau americain, Grimpereau brun (French)
- Trepadorcito norteamericano, Trepador americano (Spanish)
- The naturalist W.M. Tyler, writing in 1948, captured this species’ energy and fragility in a memorable description, “The Brown Creeper, as he hitches along the bole of a tree, looks like a fragment of detached bark that is defying the law of gravitation by moving upward over the trunk, and as he flies off to another tree he resembles a little dry leaf blown about by the wind.”
- The Brown Creeper builds a hammock-like nest behind a loosened flap of bark on a dead or dying tree. It wasn’t until 1879 that naturalists discovered this unique nesting strategy.
- In Arizona, Brown Creeper nests often have two openings, one which serves as an entrance and the other as an exit. Entrances face downward and exits upward.
- Sometimes creepers build nests in unusual places, such as behind window shutters, in or under roofs, inside fenceposts, or inside concrete blocks. One brought up a family in a specially constructed box made of pieces of Douglas-fir bark.
- Wildlife managers sometimes use the Brown Creeper as an indicator species to help gauge the effects of logging on wildlife habitat.
- Brown Creepers burn an estimated 4–10 calories (technically, kilocalories) per day, a tiny fraction of a human’s daily intake of about 2,000 kilocalories. By eating a single spider, a creeper gains enough energy to climb nearly 200 feet vertically.
- The oldest Brown Creeper on record was at least 4 years, 5 months old and lived in Illinois.
The Brown Creeper prefers forests with many large live trees for foraging and large loose-barked (often dead or dying) trees for nesting. In the summer it tends to live in mature coniferous forests; the tree species vary greatly across its range, but can include redwood, Douglas-fir, ponderosa pine, spruce, eastern hemlock, white pine, and bald cypress. In the winter it uses a wider variety of wooded habitats from deciduous forests to suburbs to parks to orchards. In winter in north Texas and the Midwest, creepers are particularly common in oak-hickory forests and tree savannas. Brown Creepers breed up to about 4,500 feet elevation in eastern North America and all the way up to treeline (around 11,000 feet) in parts of the West.
In the breeding season, Brown Creepers eat insects and their larvae (including stinkbugs, fruit flies, gnats, beetles, weevils, bark beetle parasitoids, butterflies, moths, lacewings, caddisflies, scale insects, leafhoppers, katydids, flat-bugs, plant lice, ants, and sawflies) along with spiders, spider eggs, and pseudoscorpions. They mainly patrol large, live trees with deeply furrowed bark, which harbors the highest densities of insects. They glean, probe, and peck at the trunk with their long, downcurved bills. Starting near the bottom of the trunk, they work their way up the tree to within several feet of the top, then fly to the bottom of another tree (or sometimes the same one) to begin again. In the winter they maintain the same diet of insects and other arthropods, but may also eat small amounts of seeds and other plant materials. Creepers may visit seed and suet feeders.
- Clutch Size
- 5–6 eggs
- Number of Broods
- 1 broods
- Egg Length
- 0.6–0.6 in
- Egg Width
- 0.5 in
- Incubation Period
- 13–17 days
- Nestling Period
- 14–20 days
- Egg Description
- Smooth and white, speckled with pink or reddish-brown.
- Condition at Hatching
- Eyes closed and bodies almost completely naked except for long, dark-gray down on the head.
The female takes a week or two to build the nest, while the male helps by bringing nesting material (he often sings nearby). She builds the frame of the nest by layering twigs and strips of bark. She uses insect cocoons and spider egg cases to stick those materials to each other and to the inner surface of the tree bark. The nest cup, up to 2.5 inches deep and 6 inches across, consists of wood fibers, spider egg cases, hair, feathers, grass, pieces of leaves, lichens, and mosses. Some of the materials may be used twice, once to build the base and later taken from the base to build the nest cup.
Both adults investigate several possible nest sites. They almost always choose a spot between the trunk and a loose piece of bark on a large, dead or dying tree—either deciduous or coniferous—in a dense tree stand. They occasionally nest in large live trees with peeling bark or in dead portions of live trees. Nests are between a couple of feet off the ground and 40 feet up.
The Brown Creeper spends most of its time spiraling up tree trunks in search of insects. It holds its short legs on either side of its body, with the long, curved claws hooking into the bark, and braces itself with its long, stiff tail. Both feet hop at the same time, making the bird’s head duck after each hop. Because of its specialized anatomy, the Brown Creeper rarely climbs downward: once high in a tree, it flies down to begin a new ascent at the base of a nearby tree. During breeding season, males have intense singing competitions to establish and defend territories of 5–15 acres. Males fly in fast spirals when pursuing a potential mate. Creepers are probably monogamous, with partners staying together until several weeks after the chicks fledge. Both parents may feed the fledglings. Territories break down late in the breeding season, and in the winter creepers often roost communally and join flocks with other species to forage. Adults may be preyed upon by domestic cats and Northern Shrikes, among other predators. Nests are in danger from red squirrels, northern flying squirrels, golden-mantled ground squirrels, wood rats, and deer mice. When adults see or hear a predator, they freeze, silently pressed against the bark. Creepers have been seen chasing chipmunks and joining groups of nuthatches and kinglets to mob jays.
Brown Creeper populations were stable or slightly increasing between 1966 and 2010, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population an 9.3 million, with 65 percent spending part of the year in the U.S., 43 percent in Canada, and 8 percent in Mexico. They rate an 8 out of 20 on the Continental Concern Score and are not on the 2012 Watch List. Timber harvesting in the West, including both clearcutting and selective cutting, has removed many of the large, live trees in which creepers forage, and salvage-logging has removed many of the dead and dying ones they nest in. Forests are also becoming more and more fragmented, posing another threat to creepers. Populations may have increased in New England in recent decades, possibly because forests have regrown and many large trees have been killed by gypsy moths and Dutch elm disease, creating nesting habitat. Spraying of DDT to combat Dutch elm disease in the 1950s may have harmed Brown Creeper populations.
Resident to short-distance migrant. Over most of their breeding range, Brown Creepers do not migrate, although northern and high-altitude populations move south or downhill in winter. Banding records indicate that Brown Creepers from parts of Canada can move as far south as North Carolina and Arkansas in winter.
Though they eat mostly insects, in winter Brown Creepers will eat suet and peanut butter, and occasionally sunflower seeds, pine seeds, grass seeds, and corn. You’re more likely to see them if there are large, old trees nearby.
Find This Bird
Brown Creepers are well camouflaged and inconspicuous against tree bark in a shady forest, but if you keep your eyes peeled for movement, you may find a creeper zigzagging upward as it gleans insects from the trunk, or see the small shape of one dropping from high on a trunk to the base of a nearby tree. Once learned, the high, insistent call note can alert you to the presence of these birds. Look for Brown Creepers in mature woods, if possible, though you can also find them in parks and suburban areas in the winter.