Wildlife Watching Wednesday: The Brown Creeper Is A Stealthy Insect Hunter

By: Tom Berg

Most birds are great insect hunters. Robins, woodpeckers, barn swallows – there are plenty of birds that hunt insects. One of the most secretive bug hunters, however, is the brown creeper (Certhia Americana). Brown creepers are very small woodland birds that resemble nuthatches as they work their way up the trunks of large trees, searching among the cracks and crevices of the tree bark for insects and spiders to eat.

Brown creepers are named for their mottled brown coloration; they are speckled with varying shades of brown above with a white belly. The dappled brown colors on their backs blends almost perfectly with the bark on the trees they climb, making them surprisingly difficult to see. They have a long, thin bill that curves slightly downward, which works very well for extracting insects from between the cracks of tree bark.

Although brown creepers are slightly smaller than most sparrows, they have a big appetite. Insects like ants, moths, beetles, flies and gnats are among the brown creeper’s favorite foods, but they also like to eat weevils, stinkbugs, spiders, spider eggs and a host of other creepy crawlies (and their larvae).

Ornithologists have studied brown creepers and determined that they typically burn 4-10 calories per day. Though we do not know how many insects they must consume to produce the energy equivalent of 4-10 calories, scientists have noted that brown creepers get enough energy from eating one spider to climb a tree trunk nearly 200 feet vertically.

One interesting thing about these diminutive birds is how and where they build their nests. They build a hammock-like nest behind a loose piece of bark on a dead tree, using bits of spider web, spider egg cases and pieces of moth cocoons to glue together the nesting materials: slender twigs, grasses, leaves and shredded bark. Bird watchers didn’t even know about this distinctive nesting tactic until 1879 – which is pretty recent considering how long humans have been watching birds!

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