Bird of the Month: Rock Wren (Salpinctes obsoletus)

Just in time for the changing season, you can listen for this bird of the month’s song! Rock Wrens are remarkable singers that can have a song repertoire of more than 100 song types, many of which appear to be learned from their neighbors.

One of my favorite, and less conspicuous birds of the southwest, is the Rock Wren. I still remember the first time I heard its distinctive call while out hiking. It was so unique and different from the bird calls I was familiar with that I instantly knew that whatever bird it was, I was just now discovering it. I looked up towards the mountain and saw a little pale bird sitting on the highest point of a large boulder. The way it bounced around on its short little legs and making its sweet little calls, I found it to be so adorable that in the midst of this unforgiving landscape, there was this fluffy little creature seemingly having the time of its life.

This small, compact bird ranges from 5 to 6 ½ inches in length from its long, sharp bill to its moderately long, squared-tipped tail. The genus name of this species comes from an ancient Greek word meaning “trumpeter” which is fitting as I often find them perched on top of a boulder singing away as if to announce the arrival of an important dignitary. Rock Wrens are quite remarkable singers that can have a song repertoire consisting of over 100 song types, many of which appear to be learned from their neighbors.  Despite having a large array of songs, they typically make recognizable falling chirp/chip or whistle calls that have a trill sounding component to them, which serves as a good identifying trait when out in the field.

Populations of Rock Wrens can be found as far north as southwestern Canada and as far south as southern Mexico. Their East-West range expands from the west coast to the Dakotas. For most parts of the year, excluding winter, the Rock Wren’s range includes Canada, Washington, Oregon, Idaho, Montana, Wyoming, Utah, and Colorado. Populations can also be found year-round in Arizona, New Mexico, and parts of Texas, Nevada, California, and Mexico.

Compared to some of its more colorful family members like the Cactus Wren or Canyon Wren, the Rock Wren has an overall pale look. The back is usually brown and speckled with gray flecks while the chest is typically pale with fine streaks, however these streaks are not always visible or may be difficult to notice. The flanks of the Rock Wren, which are the regions between the abdomen and the underside of the wings, are a more yellowish-brown color and are often quite fluffy. They have brown wings with gray speckles and dark brown barring near the edges and a russet tail ranging from black to brown visible when they take flight.

Rock Wrens have interesting nesting behaviors that are not entirely well understood, but what is known is that their nest sites are often found in crevices among boulders or under big rock ledges that provide shelter. They may also select nest sites among small holes in steep dirt banks or in protective crevices of stone buildings. Their cup-shaped nests are made from grasses and other small herbaceous plants, small twigs, strips of bark, and rootlets. They line the inside with finer materials such as spider webs, animal hair, and feathers. These nests typically sit either on the ground or a few inches above, on top of a foundation or small rocks, which is why the Rock Wren is considered a ground nesting bird. Although not confirmed, there is good evidence to suggest that both males and females participate in construction of the nests. Once they have chosen their nesting sites, males protect their territory by finding a good boulder to perch on and will sing songs to let other Rock Wrens know that this territory has been claimed.

The most interesting and unique part about their nesting behavior is the construction of “paving” or a “front porch” that typically marks the entrance to the nesting site. The “paving” is often lined with small stones, bones, and other debris. The reason for this “front porch” is still unknown but it must be important to the Rock Wren since they build this “paving” before constructing the actual nest. This behavior also serves to distinguish a Rock Wren’s nest from other ground nesting wrens such as the House Wren.

Rock Wrens are mostly insectivores that can be found foraging in dry places either on the ground or among the crevices of boulders, cliffs, steep banks, or anywhere with lots of cracks and crevices for small bugs to hide. Using their long sharp beak to pry in small spaces, they are likely eating mostly beetles, grasshoppers, ants, and a healthy dosing of spiders. They often fly from boulder to boulder but they can also run surprisingly fast when on a flat surface. The next time you find yourself is a dry, rocky area, look out for one these birds. They will likely be standing on a rock and using their short little legs to bob up and down as they sing.

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