Sharol Nelson-Embry is a volunteer with the Golden Gate Audubon Society.
Western Bluebird Colors Isle of Style
Many people have heard of the “bluebird of happiness,” a phrase that has roots stretching back thousands of years in multiple cultures including: Native American, Chinese, French and German. Stories and legends associate bluebirds with hope, springtime and home.
Well, I’ve been waiting a long time for local western bluebirds to visit my yard. I’ve seen them all around the Island and in nearby neighborhoods, but not on my street. Then, in a flash of brilliant, royal-blue feathers, a male western bluebird came to my backyard a few weeks ago, followed by a flutter of young bluebirds and their more drab-colored mother. The western bluebirds have been steadily expanding their territory from pockets around the Island. Have you noticed them?
Western bluebird males are fairly easy to identify with bright blue feathers on their backs, heads and tails. The chests are rusty-orange and the abdomens a creamy white. Females are a duller gray with some blue feathers on their backs and wings and a blush of rust on their chests. Very young birds are brownish overall with spotted gray-brown on their backs and streaking on their chests. This provides good camouflage as they learn to fly and hunt.
Western bluebirds are between sparrow- and robin-sized. Males and females pair up for the breeding season and select nest sites. As cavity nesters, they can’t excavate their own nests, and instead rely on abandoned woodpecker nest holes, dead trees or holes in trees made by other animals. They readily use nest boxes.
The female collects grasses, straw, moss and other plant fibers along with fur, feathers and even small pieces of plastic to create a loose cup inside the nest cavity.
She lays 2 to 8 pale-blue eggs (sometimes white) and incubates them for 12 to 17 days. Both parents, and in about 15 percent of cases some helper birds — scientists think they’re last year’s young, or even other adults whose nest may have failed — feed the helpless young. They bring insects and larvae to the young for the next 3 weeks.
Then the young “fledge” out of the nest to nearby branches or bushes and the parents continue to feed them for several weeks. Parents then may nest a second and even a third time during the season. Only about half of the young birds make it to adulthood with predators and the risky business of finding their own food and territories claiming the other 50 percent of young birds.
In 2012, when I was the supervising naturalist at Crab Cove with the help of a school group we installed six nest boxes near the pond at Crown Memorial State Beach. Before then bluebirds had been seen at Alameda Point near the soccer fields, but I wasn’t aware of any nest boxes or nest cavities near Crab Cove. Since then, more nest boxes have been added in the park, and I suspect around town, with most being used by these beautiful bluebirds.
They’re now a common sight here, staying year-round. Statewide, the western bluebird population has tripled since 1998 — good news since their numbers dropped due to the common use of DDT in the middle of the last century. Currently the population is holding steady or growing.
There are still multiple threats to western bluebirds, though, including competition for scarce nesting cavities. Non-native house sparrows and European starlings often outcompete bluebirds for tree cavities and nest boxes.
Alameda residents can help bluebirds by installing nest boxes built to the specifications that exclude other birds but are a perfect fit for bluebirds. Plans are available online at nestwatch.org/learn/all-about-birdhouses/birds/western-bluebird. Planting native flora that encourages the insects bluebirds eat, as well as berry bushes whose high-energy fruit they consume in winter also helps. Native plant suggestions for Alameda are available online at www.audubon.org/native-plants.
Climate change looms as a threat to more than 170 California bird species including the western bluebird, according to a seven-year study by the National Audubon Society. The change may create food scarcity for bluebirds if the timing of plant blooming, fruiting and insect abundance are offset by warmer or cooler weather patterns.
Support local birds and learn more by joining the Golden Gate Audubon Society or by coming along on the society’s free field trips.