The U.S. national bird, known for its dramatic wingspan of up to 8 feet (2.4 meters) and its 200 mph (320 kph) flight speed, has another superlative ability: nest building [source: San Diego Zoo].
Bald eagles, like most other birds, build their nests in trees. Unlike most other birds, bald eagles build nests that can break those trees.
A typical bald eagle nest is big: up to 5 feet (1.5 meters) in diameter and up to 6 feet (1.8 meters) deep. But that's nothing compared to the largest nest ever discovered. One found in Florida in the 1960s had a weight of more than 2.2 tons (2 metric tons), a diameter of 9.6 feet (2.9 meters), and a depth of 20 feet (6 meters) [source: Guinness World Records]. Another that fell out of a tree in Ohio in the 1920s was 8.5 feet (2.6 meters) across, 12 feet (3.6 meters) deep, and weighed about 2 tons (1.8 metric tons) [source: Ohio Dept. of Natural Resources].
How does a pair of birds build a nest that massive? Slowly. Bald eagles use the same nest year after year, sometimes for decades, and they're constantly adding twigs, branches, moss, feathers and other nesting material [source: San Diego Zoo]. The Ohio Department of Natural Resources estimates that bald eagles, likely more than one mating pair over time, had been building and living in that 2-ton Ohio nest for about 35 years before it fell [source: Ohio Dept. of Natural Resources].