Eastern bluebirds are preparing for the first of the two or three broods they will raise this summer. Contrary to what those of us who clean out our bluebird boxes have been led to believe, Cornell Lab of Ornithology states that experiments show preferences for nesting boxes containing old nests. In a paired experimental design bluebirds chose boxes containing old nests in 38 of 41 cases in which boxes with old nests were paired with empty ones. Scientists conjecture that this may be because the old nests often contain wasp larvae, an easy source of food for the bluebirds.
Females build their nest over several days. Grasses and pine needles are gathered from the ground and delivered to the nest box. Fine grasses, horse hair and turkey feathers often provide the soft, innermost lining of the nest. While the male enters the box during the nest-building process, perhaps to inspect, he does not actively collect material or participate in the building of the nest. Once the 3 – 7 eggs are laid, the female spends the next two weeks or so incubating them. She then broods the young for about a week, and both parents provide them with food for up to three weeks after the young have fledged. (Thanks to Jeannie Killam and Terry Ross for photo op.)
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