From the perch, they scan below them for insect movement, and they also take wing to capture flying insects. In times of cold weather when insects are scarce, bluebirds shift to fruit. Some feeder operators have lured bluebirds in by offering mealworms, suet mixtures, moistened raisins, and other fruits. Whenever available, insects are the food of choice for bluebirds. The eastern bluebird, in particular, has been greatly helped by the efforts of concerned bird watchers to provide housing that excludes nest site competitors such as starlings and house sparrows.
Males wave their wings and call in a display at the nest site.
Females weave a nest of grass and rootlets inside the cavity. Four to six pale blue eggs are laid, and incubation lasts about two weeks. Fledging is about 15-21 days after hatching. Second, and occasionally third, broods are attempted.