Eagles are large, powerful birds of prey in the Accipitridae family, though only the subfamily Aquilinae are considered "true eagles" genetically—the term is commonly applied to many big raptors like the bald eagle. Of the 68 species worldwide, most are found in Eurasia and Africa, with just 14 elsewhere (2 in North America, 9 in Central/South America, and 3 in Australia). These apex predators boast hooked beaks, strong talons, and extraordinary vision—the wedge-tailed eagle's eyesight is twice as sharp as a human's—and females are always larger than males. They build nests called eyries on high cliffs or tall trees, and while they lay two eggs, the older chick frequently kills its younger sibling. Their diets vary by genus: fish eagles (Haliaeetus) catch fish, snake eagles (Circaetus) hunt serpents, and Aquila eagles take medium-sized vertebrates. The word "eagle" derives from Latin aquila via Old French, replacing the native English term "ern," which still survives in names like the white-tailed eagle.