Western Bluebird is a member of the thrush family. It is approximately 7 inches long, with a short tail, pointed wings, a small dark bill, bright blue head, wings and rump. Breast sides and patch on the back are rusty brown. The female is greyer, paler, but has rusty color on breast. Juveniles are similar in color to the female, but browner and their breasts are heavily spotted. Life span is up to 6 to 10 years, but more typically is 5-6 years. There are two other species of Bluebirds: Eastern and Mountain.
History in the Northern Willamette Valley:
Western Bluebirds were prevalent early in the twentieth century when small farms with interspersed clearings and woodlands dominated the Willamette Valley. The bluebirds used holes in snags, dead and dying trees and wooden fence posts to build their nests. They relied on native berries during the winter such as mistletoe berries growing in vast tracts of oak trees. The natural cavities and food sources diminished as residential development and large-scale agriculture replaced the oaks and family farms, and the use of insecticides increased. With fewer nesting sites and traditional food sources, and the growing competition from European House Sparrows and European Starlings,which were introduced from England, the Western Bluebird retreated into higher elevations to breed. By the mid-1940’s bluebirds were only found in places like Ladd Hill near Sherwood, and Parrett and Chehalem Mountains near Newberg. Because the population was at risk, the State of Oregon listed the Western Bluebird as a “sensitive” species in the northern Willamette Valley. Prescott Bluebird Recovery Project was started in the 1970’s to help save the bluebirds in this area.
Cold spells during Oregon’s typically rainy springs can take a great toll on both the young and adult bluebirds. The adults are stressed maintaining their own nutritional needs as well as those of their young during cold spring weather when insects are not as active. The females are even more challenged as the recently hatched bluebirds depend on the warmth of their mother’s body to survive. The very cold and wet springs of 2010 – 2012 have been particularly hard on the juvenile and adult population of bluebirds.
Musical single call note of “tew” either singly or linked together. Listen to the bluebird calls at allaboutbirds.org.
Bluebirds need open space with short grass and interspersed with trees so they can perch and survey the area for insects on the ground. Residential acreages and pasture land are their preferred habitat. They don’t nest in cities and rarely nest in suburban developments.
Bluebirds primarily eat insects (spiders, crickets, ants, grubs and small worms) and to a lesser extent berries, especially in winter. They typically hunt insects by perching or hovering and then swooping down to capture them. They usually do not spend a lot of time on the ground like a robin, nor do they typically catch insects on the fly. Volunteer monitors attract Bluebirds during their nesting by offering them mealworms.
Bluebirds are secondary cavity nesting birds. They do not excavate their own nesting cavity but use natural cavities or cavities created by other species such as woodpeckers. Prescott Bluebird Recovery Project places and maintains nesting boxes in the northern Willamette Valley. Click for map of monitored areas. The specifications for the size and shape of the box as well as the placement of the boxes is very specific to the needs of the Western Bluebird. It is not recommended to put up nest boxes that do not meet the specific needs of the Western Bluebird or in habitat not attractive to the Western Bluebird as the boxes may attract other competitive or predatory birds.
Beginning in March and April the bluebirds begin pairing up. The male selects and protects a nesting area which may include several nesting sites. The female selects a nesting site within the male’s territory and builds a neat cup-shaped nest made almost exclusively of dry grass. She lays four to six blue eggs (called a clutch) that she alone incubates 13 to 14 days until the eggs hatch. During the next three weeks while the nestlings are in the nest they are fed by both parents. Only the female broods them.
However, if something happens to her during incubation or before the nestlings are fully feathered, the male who has no brood patch cannot keep them warm, and they generally perish. Once the nestlings are about 12 days old, however, a male alone can successfully raise the young birds. While the young are in the nest, the parents keep it clean by removing a fecal sac each time they go into the nest box to feed the nestlings. After fledging the young still must be fed by their parents for two to three weeks until they learn to fend for themselves. The female usually leaves that task to the male with the occasional help of offspring from the prior clutches. The female then adds new material to the nest and starts laying four to five more eggs for her second clutch. By the time the second clutch is raised, the parent bluebirds will have invested three to four months in producing the next generation of bluebirds.
The bluebird population in the northern Willamette Valley does not migrate in winter. Family groups usually stay together, moving down from higher elevations to the valley floor in search of dried berries and insects. Champoeg State Heritage Area near Newberg is a good place to see Western Bluebirds year round.