The bald eagle has a full head of feathers, and builds a one-ton nest
America's national bird is not bald at all. Its name uses an old sense of the word meaning white-headed, the same idea behind its scientific name, which translates as white-headed sea eagle. It also builds the largest tree nests ever recorded for any animal, some weighing about a metric ton.
The bald eagle is a sea eagle of North America, ranging from Alaska and most of Canada through the contiguous United States into northern Mexico, wherever big stretches of open water offer plenty of food and old trees for nesting. Mostly it eats fish, dropping down to pluck them from the surface with its talons, though it takes whatever opportunity offers. Its nests can reach 4 metres deep and 2.5 metres wide.
Adults are dark brown with a gleaming white head and tail, a heavy hooked yellow beak and yellow feet and eyes. Males and females wear the same plumage, but females are about a quarter larger. Young birds are brown with messy white streaks and take until the fifth year, occasionally sooner, to reach adult colours and breed. The long rear talon does the killing, stabbing prey held still by the front toes. Carl Linnaeus first described the species in his Systema Naturae as Falco leucocephalus.
Its closest relative is Eurasia's white-tailed eagle, a tan-headed bird of similar size that fills the same role across the Old World. The pair branched off from other sea eagles at least 10 million years ago, and perhaps as far back as 28 million. Two subspecies are traditionally recognised, a larger northern one and a smaller southern one, though the difference may simply reflect the tendency of animals in colder climates to be bigger.
By the late 20th century the bird was close to disappearing from the lower 48 states. Hunting bans and the prohibition of the pesticide DDT turned things around, and the population rebounded enough for its status to be eased from endangered to threatened in 1995 and for it to be taken off the list entirely in 2007.
Source: Bald eagle
