Bird of the month: Rock Wren

Rock Wren is an apropos name for a bird that lives in sparsely vegetated, arid and rocky canyons.

These birds breed on talus slopes, scrublands and dry washes, from desert to alpine in western North America. They are also found in nonrocky environments if there are crevices, nooks, crannies and recesses available, and will even use concrete or stone buildings and other structures. 

I saw my first rock wren in Utah at the visitor center of Dinosaur National Monument near Jensen. A metallic trilling call note that seemed to echo around the rocks caught my ear. Walking toward the sound, I scanned the barren rocky hillside. These pale grayish birds blend in well with the similar-colored landscapes they prefer, and it took a few moments to locate the bird. Or birds, as it turned out. They were a pair bouncing up and down on short legs. As I watched the birds, I noticed what appeared to be a little pathway built of pebbles and small flat stones leading to a rocky crevice. Believe it or not, this “front porch” to the nest cavity was built by the rock wren pair. 

Socially monogamous, rock wrens pair up for the breeding season and may have up to three broods of up to five or six eggs each. Males guard the female and bring food to her, especially before egg-laying. The pair builds a loose cup nest of grass, weeds, and twigs, lining it with animal hair, spider silk and feathers. The nest site is often reused from year to year. 

The foundation of the nest is made of pebbles and extends out from the nest to form a “front porch” or “sidewalk.” Some couples get quite elaborate with their porch by incorporating human-made objects and hundreds of stones that can be up to a foot in length. Scientists are uncertain of the function of this pathway. One theory speculates that the raised pathway decreases the size of the opening to the nest, protecting it against predators. It may also function to keep the nest dry. 

An equally interesting fact about rock wrens is that they are not known to drink water, even in captivity. They glean water from the insects, spiders and earthworms they extract from crevices with their fine bills as they hop along. They take prey caught in spiders’ webs and will supplement their diet with seeds and other plant matter. 

Your best bet to find a pair of rock wrens is to hike into a dry, rocky area in the cool of morning during the nesting season, May through early September. Listen for the male singing as you scan stony perches. 

Likely hotspots near the Flathead include Cromwell Creek Road, SKQ Dam and the CSKT Bison Range.