Bald eagles are captivating birds of prey. Their reproductive journey, from nest construction to the emergence of young, showcases their dedication as parents.
The Incubation Period
Bald eagle eggs incubate for approximately 35 days, varying slightly from 34 to 36 days. Both male and female bald eagles share incubation, though the female usually undertakes the majority of duties, spending more time on the nest.
Parental eagles maintain the eggs at a consistent temperature, close to 105 degrees Fahrenheit. They regularly turn the eggs, often every one to two hours, using their feet and beak. This turning prevents the developing embryo from sticking to the inside of the shell and ensures uniform heat distribution. During nest exchanges, adults are careful to clench their talons to avoid puncturing the eggs.
Nesting and Egg Development
Bald eagles construct some of the largest bird nests in North America, often measuring 5 to 6 feet in diameter and 2 to 4 feet deep. These massive structures are built in tall, sturdy trees, offering clear views and easy flight access, though they can also be found on cliffs. Both male and female eagles contribute to nest building, weaving large sticks together and lining the central nest cup with softer materials like grass, moss, and their own down feathers for cushioning and insulation.
Egg laying varies geographically, from as early as October in southern states to late April in northern regions. A typical clutch size is one to three eggs, with two eggs being the most common. Eggs are not laid daily; it generally takes a female three to six days to complete her clutch. Each egg is dull white, weighs around 110-130 grams, and has an oval shape.
Hatching and Early Life
The hatching process for a bald eagle egg can take up to 72 hours. Approximately four days before hatching, the eaglet develops a small, sharp projection on its beak called an “egg tooth.” The chick uses this egg tooth to first internally pip, breaking through an inner membrane to access an air cell and take its first breath. This provides the energy needed for the external pip, where the egg tooth creates a tiny hole or crack in the outer shell.
The eaglet then continues to peck and scratch, weakening the shell in a process known as “pipping” or “zipping.” Once the shell is sufficiently weakened, the chick pushes its way out. Newly hatched eaglets are semi-altricial, largely helpless, covered in light gray down, and depend on their parents for warmth and food. Parents will tear small pieces of food, often fish, to feed their young, and one adult typically remains on the nest to brood and guard the hatchlings.