by Charly Kearns, Land Steward
Western bluebirds are now a common sight at the Land Trust’s Powell Creek Pastures property, along the Nisqually River. It’s always a joy to see them hunting for insects or perched on fence posts. They are a cavity-nesting species but are unable to create their own nests, so they rely on woodpeckers, tree rot, and humans to create safe places to lay eggs. Volunteers have helped us install dozens of birdhouses throughout the Pastures property, and we have watched bluebirds successfully fledge multiple generations of young.
Bluebirds prefer open woodlands, like the Pastures, but are found in different habitats throughout the western United States. In summer, they primarily eat terrestrial insects, like caterpillars, pill bugs, and grasshoppers. In winter, they largely depend on seeds and hard berries. And, though stable, Western bluebird populations do face risks: habitat loss from development and extensive logging, loss of openings due to fire suppression, removal of dead trees, and invasive species, such as European starlings and feral cats.
Bluebirds have a fascinating and unusual family dynamic. Nesting pairs may allow some sons to remain within their defended territory but will cast out most daughters. The stay-at-home sons may try to mate with outcast daughters from neighboring territories and eventually create their own territory. However, some sons may not mate at all, and instead stay within their parents’ domain and help care for offspring. This cooperative breeding strategy significantly increases the survival rate of fledglings.
Henry David Thoreau wrote that “the bluebird carries the sky on his back.” This is actually closer to the truth than you might think. The color blue is rare in nature, especially in the animal world. In fact, the only vertebrate known to actually produce a blue pigment is a group of fish. All other blue-colored vertebrates get their color from structural elements. In bluebirds (and most blue feathers), this is accomplished by tiny air pockets within the barbs of feathers, which scatter light, reflecting only blue wavelengths.
These somewhat common birds are anything but ordinary, and we love providing them with a home!