Bald Eagles require five to six years to be their full adult size. Juvenile birds are dark brown, and are often taken to be Golden Eagles. Second and third year birds show considerable white on their undersides, but by the fourth year, the white of the head and tail are beginning to show. As in most birds of prey, females are larger than males, and may reach a weight of over five kilograms, carried by a wingspan of two meters or more.
Bald Eagles may be seen at any time of the year, but they often gather in large numbers when food is plentiful. In the spring, when the herring spawn, the eagles join thousands of seabirds, and marine mammals, off the east coast of Vancouver Island. In the fall and winter, they move to the salmon streams to feed on the spawned-out fish.
On Vancouver Island, Bald Eagles build their nests at the top of large conifers selecting trees with open access, good visiblity and close to water. The nest can weight several hundred kilograms and are used over many seasons.
Except in cases where a breeding pair cannot produce offspring, eagles mate for life. One to three eggs are ususl with both the male and female incubating the eggs.