According to the internet (which automatically makes it true): The average bald eagle nest is 4 to 5 feet in diameter and 2 to 4 feet deep. Each year the adult pair will add 1-2 feet of new material to the nest. The largest recorded bald eagle nest, located in St. Petersburg, Florida, was 9.5 feet in diameter, 20 feet deep and weighed almost 3 tons.