Adult Bald Eagle, Image by Larry Hickey
This month, let's talk about a raptor (bird of prey) that’s being seen more often in the Sacramento region, the Bald Eagle. Populations live in many regions within the United States, Canada, and northern Mexico. Bald Eagles can live for many years; one bird was reported to have lived 39 years in the wild and another to age 50. Despite their large size, they are agile fliers (able to move quickly and easily). They can reach speeds up to 70 miles per hour and soar with flat, straight wings. Bald Eagles are frequently seen alone or in pairs; but in winter they will gather together in numbers at resting or feeding sites. When on the ground walking, their gait appears somewhat awkward. Bald Eagles walk with a back and forth rocking motion.
Bald Eagles were put on the endangered species list in 1978; but thankfully their numbers have gradually recovered due to national protection measures and after the use of the pesticide DDT was banned.
Some Bald Eagles will migrate (to move from one region or habitat to another according to the seasons) if the water freezes where they catch fish or when juveniles leave the nest. Bald Eagles instinctively use migration routes that have good flying conditions and food sources. Their migration generally takes place during the daytime when thermals (upward currents of warm air) are produced by the sun.
What do Bald Eagles look like?
Adult Bald Eagle, Image by Larry Hickey
The heads of Bald Eagles are not bald; they have feathers on their heads. The species was given their name because of the old English word ‘balde’ meaning ‘white-headed’. Adult Bald Eagles stand out because of the huge contrast between their dark-brown bodies and their bright white heads, necks, and tails. They have whitish-yellow eyes, large hook-shaped yellow bills, yellow feet with large talons, and feather-less legs. Although males and females look the same, female birds are about 25% larger than males. Females can have a wingspan of up to 8 feet, whereas males have a wingspan of up to 6 feet.
Immature Bald Eagle, Image by Jane Van Kessel
Baby eagles, called eaglets, are light gray when born and change color over time. It takes 4-5 years for young birds to look like adult Bald Eagles. Young birds have varying amounts of white streaking on their wings and tails. Their tails can also have a dark band at the tip. The bodies, necks, and heads of young Bald Eagles can be either solid brown or are mottled (spotted or splotchy) with patches of white and brown. Young birds have dark bills and eyes; but these gradually become lighter in color like on adult birds.
Bald Eagles can easily be mistaken for Golden Eagles, which is another eagle species that is seen in the Sacramento Valley. They are also sometimes mistaken for Turkey Vultures or large hawks.
Where do Bald Eagles live?
Bald Eagles prefer habitats near bodies of open water that have large trees for their nests. They are seen near rivers, grasslands, marshes, lakes, streams, sometimes coastal areas, and in mountain ranges when they are migrating. They can also be found in drier and more inland areas in winter.
Bald Eagles make the largest nests in North America. They frequently reuse and rebuild their nests year after year. Because they add additional materials to the nest each year, their nests can weigh up to 1-2 thousand pounds! Sometimes other bird species, such as Great Horned Owls, use abandoned Bald Eagle nests.
Adult Bald Eagle high on a nest, Image by Jane Van Kessel
Bald Eagles usually nest in trees. Pairs frequently remain together for life. They tend to choose the tallest tree in an area so that they have an excellent view of their surroundings. It can take up to three months for the pair to build a nest. Both parents carry building material to the nest site. Large sticks are woven together and are covered or lined with a softer material such as moss, lichen, grass, and downy feathers. The nesting female lays 1-3 eggs per year and their eggs are the size of baseballs. For about one month, both parents take turns incubating the eggs (sitting on the eggs to keep them warm). One parent will remain with the eaglets in the nest at all times for about two weeks. The parents hunt from dawn to dusk to provide food for their young. They rip the food into small pieces for their eaglets using their sharp pointed beaks. Even after the young birds are able to fly, young Bald Eagles remain near the nest for around three months before leaving the area. It is common for the fledged eagles to return to the same area when they start nesting in about 5 years.
What do Bald Eagles Eat?
Adult Bald Eagles, Image by Larry Hickey
Bald Eagles are carnivorous (meat-eating) and will accept a wide variety of prey (animals caught by another animal for food). Their primary and preferred food is fish; but they will also consume birds (usually water birds, such as ducks and coots), mammals (such as rabbits, squirrels, and prairie dogs), reptiles, amphibians, and invertebrates. Because of their excellent eyesight, Bald Eagles can see fish in the water up to a mile away! They can swoop down from a high perch at a very fast speed and grab fish or other prey with their talons (the claws on a bird of prey). Bald Eagles sometimes will wade in shallow water either to catch fish or to drag a fish over to the shore that was too heavy to lift in flight. They will occasionally hunt in pairs, which helps make catching prey easier. Even though they are great hunters, Bald Eagles often steal prey that smaller raptors or mammals have caught. In addition, they will eat carrion (the decaying meat of dead animals), such as dead fish washed up on a shore. Bald Eagles tend to eat a large volume of food when food is available; but can go without eating anything for weeks!
What do Bald Eagles sound like?
When someone hears the call of a Bald Eagle for the first time, they are usually surprised at how high-pitched and weak-sounding it is. In TV commercials or movies where a Bald Eagle is shown, it is common for the call of a Red-tailed Hawk to be used in order to create a more dramatic effect. The calls of Bald Eagles are described as a series of chirps or a loud screaming whistle. Listen to Bald Eagle calls below.