North American Eagles
The most familiar and widespread species of eagle in North America is the bald eagle (Haliaeetus leucocephalus). Mature bald eagles have a dark-brown body, and a white head and tail. Immature birds are browner and lack the bold white markings on the tail and head. They gradually develop the rich adult plumage, which is complete when the birds are sexually mature at four to five
years of age. The bald eagle mostly feeds on fish caught or scavenged in rivers, lakes, ponds, and coastal estuaries.
Bald eagles nest on huge platforms built of sticks, commonly located on a large tree. Because the nests are used from year to year, and new sticks are added each breeding season, they can eventually weigh several tons. Northern populations of bald eagles commonly migrate to the south to spend their non-breeding season. However, these birds are tolerant of the cold and will remain near their breeding sites as long as there is open water and a dependable source of fish to eat. Other birds winter well south of their breeding range.
The golden eagle (Aquila chrysaetos) is an uncommon species in North America, breeding in the northern tundra, in mountainous regions, and in extensively forested areas. The golden eagle also breeds in northern Europe and Asia. This species has dark-brown plumage, and its wingspan is as great as 6.5 ft (2 m). These birds can predate on animals as large as young sheep and goats, but they more commonly take smaller mammals such as marmots and ground squirrels.
Golden eagles nest in a stick nest built on a large tree or a cliff. As with the bald eagle, the nest may be used for many years, and may eventually become a massive structure. Usually, two to three white-downed eaglets are hatched, but it is uncommon for more than one to survive and fledge. It takes four to five years for a golden eagle to become sexually mature.