Bluebirds, with their vibrant plumage, are a welcome sight. Their nesting cycle, from egg-laying to the first flight, offers a glimpse into nature’s processes and the care bluebird parents provide.
Incubation Duration
The female bluebird primarily incubates the eggs. This period typically spans 12 to 14 days, averaging 13.5 days, though the full range is 11 to 19 days. Incubation usually begins after the last egg is laid, or sometimes the day before, which helps ensure young hatch at roughly the same time.
The male remains close to the nest, often bringing food to the incubating female. Environmental factors, such as ambient temperature and the consistency of brooding, can slightly influence the exact incubation length. Warmer regions, for instance, may see marginally shorter periods.
The Hatching Event
The emergence of a bluebird chick from its egg is a challenging process. Each chick possesses a temporary, sharp projection on its beak called an “egg tooth.” This structure allows the hatchling to pierce the internal membrane and break through the eggshell from within. The chick creates a small hole, known as a pip, then gradually chips away at the shell, rotating its body to widen the opening until it can wriggle free.
This process can take an individual chick one to six hours. Once hatched, bluebird chicks are altricial, meaning they are born blind and mostly naked, covered only with sparse gray down. Their skin appears a bright coral-pink color. Parent birds remove or consume discarded eggshells, a behavior that helps replenish the female’s calcium reserves and eliminates visual cues that could attract predators to the nest.
Nestling to Fledgling
After hatching, bluebird nestlings undergo rapid growth and development within the nest, typically lasting 16 to 25 days before they fledge. Both parents feed the growing brood, primarily providing a protein-rich diet of insects. By day two, their skin begins to take on a bluish-black hue as feathers start to form beneath the surface.
Their eyes typically open around days five to six, and by days seven to nine, the nestlings can regulate their own body temperature, reducing the female’s need to continuously brood them. Wing feathers become visible around day eleven, and by days twelve to thirteen, the young birds are almost fully feathered, strong enough to cling to the nestbox entrance. Fledging, the act of leaving the nest, occurs when the young birds are capable of sustained flight.
Once they fledge, young bluebirds do not return to the nest. Parents continue to care for them for approximately two to four weeks (28 to 30 days) after they leave the nest. During this time, the fledglings remain in nearby protective cover, gradually learning essential foraging and survival skills from their parents.