An eagle is a large bird of prey known for having broad wings and strong flight skills. Eagles are native to every continent in the world except Antarctica. There are more than 60 species of eagle, most of them found in Europe, Asia and Africa. Eagles are like many birds of prey in that they are highly adaptable and can survive in a wide variety of ecosystems. Most eagles are grouped by species based on similar characteristics; these groups include serpent-eagles, hawk-eagles, true eagles and sea eagles.

Serpent-eagles are native to Asia and Africa. They make up a dozen species known for hunting snakes and reptiles. They and all eagle species have sharp vision; powerful talons and beaks; and swift, silent flight. All are qualities that make them efficient hunters. Serpent-eagles are not as large as some types of eagle, but they are still larger than most other birds.

Hawk-eagles are not hawks. They are eagles once thought to resemble hawks. They populate tropical regions, primarily in Central and South America but also in Asia and Africa. They can be distinguished by their prominent head crests. Although most hawk-eagles are medium in size for an eagle, the group includes the crowned eagle and martial eagle, two of the largest eagle species. Martial eagles can have a wingspan of 8 feet (2.4 meters) or more.

So-called true eagles include the golden eagle, the spotted eagle and the tawny eagle, all found in Africa, Asia and on the Indian subcontinent. A noted relation, now long gone, was the Haast’s eagle of New Zealand. Although they died out in the 1400s, Haast’s eagles were the largest eagle species known to have existed. They weighed from 20 pounds to 30 pounds (9 kilograms to 13.4 kilograms) each and could strike prey with the force of a wrecking ball.

Sea eagles include some of the largest eagles still in existence, including the Steller’s sea eagle of Asia. Sea eagles are primarily found near large bodies of water and live on fish and waterfowl. Sea eagles are among the oldest eagles; paleontological evidence suggests similar birds existed at least 12 million years ago, and possibly as long as 20 million years before that. The bald eagle is part of the sea eagle family.

The bald eagle has long been a national symbol of the United States, but it is one of only two eagle species found on the North American continent. The bald eagle was nearly driven to extinction in the mid-20th century by pesticide use and human development in eagle habitats. Conservation efforts paid off and bald eagle populations increased, especially in Alaska. The bald eagle was removed from the United States' list of endangered species in 2007.