In open parklands of the American West, brilliant blue-and-rust Western Bluebirds sit on low perches and swoop lightly to the ground to catch insects. Deep blue, rusty, and white, males are considerably brighter than the gray-brown, blue-tinged females. This small thrush nests in holes in trees or nest boxes and often gathers in small flocks outside of the breeding season to feed on insects or berries, giving their quiet, chortling calls. You can help out Western Bluebirds by placing nest boxes in your yard or park.
Occasionally Western Bluebirds have helpers at the nest. Most of the extra birds attending nests are helping their presumed parents, some after their own nests have failed. Interestingly, studies show that many nests include young that were not fathered by the resident male.
Information from the All About Birds website, , © Cornell Lab of Ornithology.