Western Bluebirds

I've mentioned before that blue-colored birds are some of my favorites, from iridescent Tree Swallows to Lazuli Buntings and Blue Grosbeaks, but of course, that list must include bluebirds themselves!  While Eastern Bluebirds are the picture-perfect postcard bird across much of the United States, out here in the West we have our own western specialties: the Mountain Bluebird and the Western Bluebird.

Male Western Bluebird

Western Bluebirds (Sialia mexicana) are with us throughout the year, and I've been seeing quite a few of them around this spring.  Birds of open woodlands and forest edges, they are also relatively comfortable in urban settings, provided suitable habitat is available.  Though they are less strictly associated with meadows and grasslands than Eastern and Mountain Bluebirds, they do still seem to prefer expanses of lawn and other open areas in town.

A male Western Bluebird, in a common pose: perched on a fence post

As cavity nesters, trees with preexisting hollows are essential habitat features.  Western Bluebirds nest in a wide variety of trees, from conifers to oaks, cottonwoods and sycamores, in naturally occurring cavities or those previously constructed by woodpeckers.  As the number of aggressive introduced cavity nesters, like European Starlings and House Sparrows, has increased, bluebirds have suffered.  Happily, these little neighborhood songbirds take readily to man-made nest boxes.  

A female Western Bluebird

While a pair of Western Bluebirds works together to scout out potential nest sites, it is the female that undertakes nest construction.  She then lays up to eight pale blue eggs in her soft, loosely woven cup nest.  A pair of Western Bluebirds may raise up to three clutches of young each breeding season.

Juvenile Western Bluebirds are spangled with delicate white spots.

Western Bluebirds are most commonly seen perching fairly close to the ground, on low limbs, fences, and sign posts, which give them a good vantage point from which to hunt their insect prey.  When a tasty morsel is spotted, they swoop down from their perch, sometimes hovering briefly, to capture insects on or near the ground.  They also catch flying insects in mid-air.

A male Western Bluebird poised to swoop down on insect prey from a low branch.

Come winter, Western Bluebirds change their diet with the seasonal availability of food, and switch to feeding predominately on berries and other fruit.  In fact, such oft maligned plants as mistletoe and poison oak are both extremely important to Western Bluebirds, furnishing them with great amounts of food that see the birds through the winter.  Large flocks of Western Bluebirds often gather together to forage on particularly heavy berry crops during the winter.

In contrast to neotropical migrants, like warblers and tanagers, the Western Bluebird's strategy of switching from an insect diet in the warm summer months to one of fruits and berries during the winter allows these birds to stay on their home turf throughout the year.  This way, they avoid the many hazards faced by long-distance migrants, which chase summer across the globe, always keeping to warm climates where insects are abundant.  Staying on or near their breeding grounds through the winter probably gives them an edge over competitors when selecting from limited nesting sites come spring.

To attract these brilliant little birds to your yard, try offering mealworms in a platform or tray type bird feeder, and put up a nest box in a suitable location.  Plant native plants, especially those that produce berries, and add a couple bird baths as well - just be sure to keep them clean!  I haven't had too much luck with bluebirds in my yard yet; the backyard isn't open enough for their taste, I suspect, because when I do see them, they're hanging out on the power lines in the front yard and swooping down over our neighbor's lawn.  Better luck to you, because watching bluebirds and listening to their soft calls is a real treat!