The largest bald eagle nest ever found weighed more than 4,400 pounds and was 20 feet deep and 9 1/2 feet in diameter. The nest was built from collected feathers, grass, sticks, moss and other organic matter. Although the St. Petersburg, Florida nest is the largest on record, a Vermillion, Ohio nest boasted a unique wine-glass shape and was in use for more than 30 years until the tree fell.
Bald eagles, which mate for life, choose a nesting site in a wooded area relatively close to water. Both birds gather the materials, while the female shapes the nest. The bulk of the nest contains sticks and wood filled in with grass and moss. The inside of the nest is lined with softer materials such as feathers and greenery. Nests located at the coast even contain seaweed and driftwood.
The bald eagle pair mates between September and April, followed five to 10 days later by a one to three egg clutch. The female incubates the eggs for about a month. Thirty-four days after the eggs are laid, the gray chicks are hatched. The eaglets are too weak to feed themselves immediately after hatching, but they grow quickly over the next two months, replacing the gray down with dark brown and black juvenile feathers. They learn to fly within the first year and leave the nest, wandering for four years until they find a mate.