Differentiated from other birds of prey mainly by their large size, more powerful build, and heavier head and bill. Larger than most raptors, except for vultures. “Eagle eye” refers to their extremely keen eyesight. Can see 8 times better than man. They have a third eyelid which acts like sunglasses. Can turn their heads 270 degrees. Have 7000 feathers, made of the same material as human fingernails. Are monogamous and mate for life. Build their nests, called eyries, in tall trees or high cliffs. Use same nest each year. Eggs are incubated for 6-8 weeks. Young mature slowly, reaching adult plumage in 3-4 years. Used by many nations as national symbols, including Czech Republic, Egypt, Ghana, Indonesia, Iraq, Mexico, Nigeria, Poland, Romania, Serbia, Syria, The Philippines, Yemen, and the U.S.