I have always been drawn to so-called secretive species of wild birds. This group of birds is characterized as birds more often heard than seen, tending to occur in dense habitats, and are otherwise shy in behavior.
A suite of other characteristics can apply, too: cryptic plumage patterns, sometimes small in body size, rare in numbers and so on. One such bird that fits the bill here in Minnesota’s forests and woodlands is the diminutive brown creeper.
Brown creepers are related to nuthatches, and it’s easy to understand why. Both nuthatches and creepers have similar body types, and both cascade up and down tree trunks and tree limbs, inching jerkily along searching for insects or caching food into fissures in the bark. And both are small and not particularly vocal, too. However, unlike nuthatches, brown creepers are extremely cryptic. They are hard to see!
Roughly 5 inches in total length with streaked-brown backsides, it’s no wonder that brown creepers are hard to pick out when observed creeping up tree trunks. These highly specialized and curious-looking birds are a joy to watch.
Unlike nuthatches, brown creepers employ a “bottom-up” approach to their creeping lifestyle. Nuthatches, on the other hand, are well-known as “top-down” foragers. Put another way, brown creepers most often fly to the lower part of a tree trunk and crawl headfirst up the bole of the tree as they hunt for insects.
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Meanwhile, and sometimes on the very same tree, nuthatches, such as white-breasted and red-breasted nuthatches, crawl headfirst from higher up the tree and down to the lower parts. Indeed, sometimes nuthatches and creepers can be observed passing by each other like two approaching vehicles on a two-lane highway.
Other notable differences between brown creepers and nuthatches (aside from obvious plumage coloration) are their bills and tails. A nuthatch bill is relatively straight and stout, whereas a brown creeper’s bill is decurved (curved downward), longish and thin. Its bill is perfect for probing, finding and capturing small insects of all kinds hiding in the cracks of tree bark.
Brown creepers’ tails are also different from those of nuthatches. Longer and used to prop their bodies against tree trunks in a woodpecker-like fashion, nuthatch tails are much shorter and are not used for leverage or support.
So, too, are the calls and songs different from their nuthatch relatives. The nasal-sounding “yak-yak-yak” calls of nuthatches are countered by the songs produced by male creepers.
These songs — high, thin notes — are difficult to discern in the forest, especially if it's windy, but are identifiable and easily detected once heard and recognized. Both male and female creepers produce call notes, too. Some descriptions of their calls are described as a “small chain being dropped in a heap.”
While I have observed and heard many brown creepers in my life throughout forests in Minnesota and elsewhere in the United States (brown creepers range everywhere in North America), I have never come upon a brown creeper nest, much less observed nestlings or parents caring for their young.
Based on outwardly body design and behaviors, one might conclude that brown creepers are cavity nesters, but they are not. Rather, these interesting little birds, staying true to their lifestyle and preferred habitat and substrate, nest within the loose bark of dead or dying trees or sometimes areas of live trees that have similar nest sites.
Only the female creeper builds the nest, while the male helps with gathering nesting material for her. Using twigs and bark, she constructs the frame of the nest while using insect cocoons and spider egg cases as the “glue” to hold everything together and against the inside surfaces of the bar.
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The nest bowl is then lined with soft fibers, grass and other items like moss, leaf parts, feathers and other soft items. About five or six eggs are laid, followed by about a month to hatch and fledge, both parents share duties in raising their offspring.
Brown creepers are cute little denizens of our forests and woodlands. Easily overlooked, these somewhat secretive feathered friends are yet another avian species to appreciate as we get out and enjoy the great outdoors.
Blane Klemek is a Minnesota DNR wildlife manager. He can be reached at bklemek@yahoo.com.
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