The bald eagle, a sea eagle, (Haliaeetus leucocephalus, from Greek hali "sea", aiētos "eagle", leuco "white", cephalos "head") is a bird of prey found in North America. Its range includes most of Canada and Alaska, all of the contiguous United States, and northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting. Bald eagles are not actually bald; the name derives from an older meaning of "white headed". The adult is mainly brown with a white head and tail. The sexes are identical in plumage, but females are about 25 percent larger than males. The beak is large and hooked. The plumage of the immature is brown. The average lifespan of bald eagles in the wild is around 20 years.