An eagle can rise on thermals and gain altitude until it is only a speck in the sky, and then it soars until it sees prey and can swoop down and make a kill. When an eagle spots a fish from the air, it begins to glide toward the water. As it nears its prey, it extends its legs and opens its talons. It soars just over the surface of the water and then plunges its legs into the water. The talons strike the fish, and the eagle immediately closes the talons, driving them deep into its prey. The eagle then flaps its wings to pull the fish out of the water and maintain enough speed to remain airborne. If the eagle cannot lift the fish, the bird may be dragged under water and forced to swim for shore. Eagles are strong swimmers, but if the water is cold, they may be overcome by hypothermia and drown.
It is a common misconception that once an eagle grasps its prey with its talons, it cannot let go. While eagles can lock their talons, it is a voluntary action. An eagle can release a fish that is too heavy for it to lift, but sometimes it holds on anyway, perhaps deciding the prize is worth the swim to shore.
Biologists estimate an eagle can only lift a maximum of four to five pounds, but since lift is dependent on both wing size and air speed, the faster the eagle flies, the greater its lift potential. An eagle that lands to grab a fish and then takes off again can manage less of a load than one that swoops down at a high rate of speed and plucks its prey from the water. Speed and momentum allow the eagle to carry more weight.
An adult bald eagle needs between 0.5 lbs (.23 kg.) and 1.5 lbs (.68 kg) of food per day. A study done in Washington State found an eagle needs to consume between 6% and 11% of its body weight per day. If an eagle eats a three-pound (1.4 kg) fish one day, though, it does not need to eat again for a few days. Bald eagles living in coastal Alaska feed mainly on fish such as herring, flounder, pollock, and salmon. They may also prey upon seabirds, small mammals, sea urchins, clams, crabs, and carrion.
In the summer and fall on Kodiak Island, eagles congregate along salmon streams or near the ocean where salmon are likely to school. Large numbers of eagles also gather near fish canneries where they feed on the fishy discharge from the processing plants. Both mature and immature eagles feed on carrion, but research indicates young eagles are more dependent on carrion, and they eat carrion while they develop and hone their hunting skills. Adults, on the other hand, more actively hunt live prey, particularly fish.
The bill and neck muscles of a bald eagle are adapted to allow the bird to gorge itself quickly. An eagle can eat a 1 lb. (.45 kg) fish in only four minutes, and it can hold onto a fish with one talon while it grips its perch with the other talon and tears apart the fish with its bill.
Eagles are the masters of their domain and consider any animal they can lift as a suitable meal. If an eagle flies over a seagull rookery, all the birds on the rookery take flight to chase away the menacing predator. Between fish, birds, voles, weasels, and hares, eagles on Kodiak Island have plenty to eat.
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