A new nest averages 2 feet deep and 5 feet across. They are lined with twigs, moss, grass, and feathers. The nest becomes larger each year as the eagles return to breed and add new nesting materials to shore up the old nest. Eventually, some nests reach sizes of more than 10 feet wide and can weigh several tons.
Breeding bald eagles typically lay one to three eggs once a year, and they hatch after about 35 days of incubation. Hunting, egg sitting, eaglet feeding and brooding duties are shared by both parents. The young eagles begin flying three months after hatching and are on their own about one month later.