Earth Journal by Gary Pendleton

Brown Creeper
A Specialist among Winter Birds

The woods are quiet except for the sound of leaves underfoot. Even in their leafless state, the bare trees muffle traffic sounds. A flock of geese breaks the silence before fading off toward the river. The place is so still that it seems asleep.

The winter birds are here. Many species congregate in mixed winter flocks: chickadees, tufted titmice, kinglets, nuthatches, downy woodpeckers and brown creepers. Because they tend to flock together, large areas seem empty of bird life. But somewhere farther down the trail they will be coursing through the woods. There is safety in numbers.

They are an eclectic mix, but they are not just a variety of species. They represent very different types. Often in a single flock you can find seven species representing five families. That makes for a remarkably diverse group. They are all small birds and they share the same wooded habitat, but the range of physical differences between them is striking.

A specialist, the creeper probes for food.

Adaptations that evolved out of different approaches to foraging for food account for the physical differences. The chickadees, titmice and kinglets are generalists; they eat a little of this and a little of that: fruit, seeds, buds, insects. As they have no need for specially adapted beaks or feet, their appearance is generic.

The woodpecker, nuthatch and creeper are specialists. Their food-finding methods include pounding, tapping or probing for insects. These birds have highly specialized body parts: strong skulls and beaks, purposeful feet and tail feathers.

The brown creeper is a short, slender bird with a downward curved bill and cryptically patterned brown and tan plumage. The long, curved bill is good for probing under bark for insects and spiders. Like the woodpeckers, the creeper has very stiff tail feathers.

Instead of perching on branches, woodpeckers and creepers usually hang on trunks and large limbs. This is where their specially adapted tails come in. The stiff tail feathers act as props that help them stay upright as they grip the trunks of trees.

True to their name, brown creepers creep. In their search for food, they creep up, never down. They are only capable of perching vertically and moving in one direction: up. Up, up and up.

Eventually they reach a point where they don’t want to go up anymore. Being birds, they then fly. So when they reach a certain point on the tree, they swoop down, like a falling leaf, to the base of another tree and start over.