Bluebirds from surrounding higher elevations move down into the park to forage for dried berries and insects. It is not unusual to see as many as a dozen bluebirds in the oak trees or on the fence lines along the bike path during a brisk winter walk. The volunteers who put up and monitor bluebird nest boxes welcome other native cavity nesting birds like Tree Swallows and Violet-green Swallows. The monitoring process for all species using the nest boxes involves counting the number of eggs laid, the number of eggs that hatch, and the number of young that successfully leave the nest. During bad weather, volunteers offer mealworms on feeding platforms to help the parent bluebirds obtain enough food to keep their nestlings warm and full.
Bluebirds are excellent parents.
The male establishes and protects the nesting territory while the female builds a neat cup-shaped nest made almost exclusively of dry grass. She lays four to six blue eggs that she alone incubates for 13 to 14 days until the eggs hatch. During the three weeks 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 can not keep them warm, and they generally perish.