American Bald Eagle
The American Bald Eagle, like all eagles, is renowned for its eyesight. The eye of a Bald Eagle is almost as large as a human’s, but it can see four times further that a person with perfect vision. These birds have two centers of focus and can see in two directions at the same time. While soaring at a height of 2,000-3,000 feet, Bald Eagles can see fish in the water and spot a prey over an area of 3 square miles. Contrary to common believes, Bald Eagles close their eyes during sleep, but they don’t blink with their lids. For blinking they have an inner translucent membrane, which slides across the eyes and wipes dust from the cornea.
The home range of the American Bald Eagle varies between 1,700 and 10,000 acres depending upon food availability. These birds hunt alone or in pairs. A Bald Eagle can eat a pound of fish in 3-4 minutes. Although Eagles don’t need much food and can do without any food for a couple of days, they have to spend the most part of the day hunting. Only one of 15 or 18 attacks is effective for most adult birds; young and inexperienced Bald Eagles often have to take advantage of carrion and can even die of hunger. These large birds waste much energy during hunting, that’s why they have to rest quietly. Eagles have a crop for storing food and separating meat from indigestible items. When the stomach is full, eagles can save a considerable amount of food there. Eagle chicks are fed regurgitated food from their parents’ crop.
The American Bald Eagle is known to steal food from other eagles and smaller raptors. When food is scarce, Bald Eagles attack more successful birds, but usually they chase the raptor persuading it to drop the prey. When Bald Eagles find an unexpected food supply, like a carcass of deer or boar, they will fight with each other, driving the weaker birds away. Younger and weaker eagles have to wait for their turn.
For many centuries people considered eagles to be fierce hunters raiding domestic stock. In fact, Bald Eagles are not strong enough to lift a large prey; they can even be dragged into water by a strong fish. All eagles are vulnerable to toxic chemicals in the environment, because they are at the top of the food chain and accumulate chemicals consumed by the prey. The American Bald Eagle became endangered mostly because of DDT and pesticides contamination; even hunting and poaching were not so much critical for its population.
