By Gail Cleveland
I am partial to nuthatches, whether Redbreasted, Pygmy or White-breasted, especially as I watch them come head-first down a fir tree in the backyard. So naturally, I am also partial to the inconspicuous and quiet Brown Creeper when I see one spiral up the trunk of a tree, probing bark crevices with its narrow, curved bill.
There are only six species in the Brown Creeper family Certhiidae, and our Brown Creeper is the only species in North America, ranging as far south as Central America. There are no South American Certhiidae; the other five very similar looking species reside in Europe and Asia.
I was sure that the Brown Creeper was related to the woodcreepers of Central America—those brown or russet birds with long, curved bills that can be seen creeping up trees and are so difficult to distinguish from one another. However, David Sibley says that woodcreepers are more closely related to flycatchers. Brown Creepers have several physical features like woodpeckers, but are not closely related. Their closest North American relatives are gnatcatchers and wrens.
According to a distribution map, Brown Creepers either reside as year-round residents or as a breeding population in every state in the U.S. Surprisingly, Brown Creepers reside year-round as far north as northern British Columbia, Canada. More often, they breed across Canada, but migrate to the southern U.S. and Mexico for the winter months. We are lucky to have them here all year in western Montana. They are rarer in eastern Montana during the breeding season and migrate south for the winters.
It seems that winter is the time that I see them the most as they creep up a tree looking for food and then fly down to the base of another tree to start up again. These “Little Brown Birds” are able to winter over because they forage primarily on tree trunks and the undersides of limbs, gleaning spiders and their eggs, insects and other small invertebrates. In summer they are exclusively insectivorous. During winter they will also eat seeds and nuts and can be found at birdfeeders. If you are interested in attracting the Brown Creeper, put out suet.
Their tweezer-like thin curved bill is perfect for removing insects from the cracks in the bark of trees. But winter can be a challenge for creepers, and, like other small birds, they have been found roosting in groups, huddling together in a crevice of a tree. More than ten in a roost is not uncommon.
Brown Creepers breed in northern coniferous forests. I have never found a Brown Creeper nest, but I keep looking. They build a nest against a tree trunk, usually concealing it under loose bark. Less often, it is concealed by a limb or is inside a cavity. The foundation of the nest is built of twigs and bark. Built solely by the female, nests are lined with finer bark shreds, grasses, feathers and moss. The male may supply her with a few building materials, but she does the construction. The building may be too mundane for the males who have been observed performing high-speed display flights among trees, circling trunks and weaving in and out of branches perusing potential mates.
But once the female has laid five to six eggs, the male gets to work, feeding her for the two week incubation period. Both sexes feed the chicks for about two weeks after hatching, before the young are able to leave the nest and cling to bark with their sharp claws.
The Brown Creeper leg is short, but the toes, especially the hind toe is particularly long, with a long, curved claw. While at a banding station on Lake Superior, I had the opportunity to hold a Brown Creeper in my hand. What I found most amazing were the feet and claws, so delicate, long and sharp as needles. This design of their feet is similar to nuthatches and other treeclingers like woodpeckers.
Like woodpeckers, and unlike nuthatches, the Brown Creeper has a long, pointed tail that is stiffened at the end for use as a prop when climbing. Plumage is predominantly brown and speckled with white, buff and black, the underparts paler than the upperparts. This mottled brown plumage conceals it from predators as it inches its way up the bark.
Until several years ago, I could not tell you that the Brown Creeper had a song. However, for two years in a row, in the spring when the warblers are arriving, my husband Bruce and I have heard a high, warbling sound unlike the normal warblers arriving in our area. Both times we found a Brown Creeper. I have a feeling that the combination of the length of the mating season, the numerous other singing passerines, and the scarcity of Brown Creepers, makes this a rarer birdsong than most. The song can be described as very high, with a thin series of accelerating, cascading notes. Sibley describes it as “trees trees pretty little trees.”
Breeding Bird Survey Data indicates that the Brown Creeper population is stable with some local declines. There can be temporary population increases where trees have died from disease, with Brown Creepers taking this opportunity to feast on insects. However, where there is extensive logging, the Brown Creeper will disappear. At the moment, here in western Montana we are lucky enough to view and occasionally hear this elusive, camouflaged Little Brown Bird as it scours our fir and pine trees for a meal.
Brown Creepers spend most of their time on main trunks or major limbs, bracing themselves with their tails like miniature woodpeckers. These inconspicuous quiet birds are easy to overlook as they spiral up the trunk of a tree, probing into bark crevices with their narrow, curved bills. After a Creeper gets to the top of a tree, it flies to the bottom of the next tree to start over. Outside of the breeding season, Brown Creepers often flock with kinglets, nuthatches, and chickadees.