Eastern Bluebirds stay in North Carolina year-round and usually begin searching for nesting sites in late February or early March. So it’s best to put up new boxes by January or early February. Days or weeks may pass before the male and female begin collecting grasses or pine straw to build a nest, usually in April. They typically build a nest in five or six days. The female begins laying eggs four or five days later. She lays one light blue (or rarely white) egg each day until the clutch is completed, then begins incubating them. The young hatch in about 17 to 18 days and spend another two weeks in the nest.
Bonded pairs can raise three broods each season—the first brood averages five young, the second brood four and the last one three, though as many as six may comprise a brood. The breeding season lasts until early September.