Species Profile: Bald Eagle


Question: What is up to 4 metres deep, 2.5 metres wide, and nearly one metric ton in weight?

No, the answer we are looking for is not a boat. Rather, a Bald Eagle’s nest. With such incredible size, it is no surprise that it houses an incredibly large bird. Bald Eagles have a wingspan that reaches 2.3 metres, with an adult body that can reach 1 metre in length. Perhaps more impressive is its body weight, ranging from a mere 3 to 6 kilograms! With a body so light and with such a large surface area, it is no wonder that the Bald Eagle is a successful bird of prey and an amazing machine of flight.

Throughout their range – which covers most of North America – fish comprise a major portion of the diet. The remainder is predominantly made up of various birds, followed by lesser amounts of small mammals, and a minor amount (~2%) consisting of “other” prey. In the Pacific Northwest (ie. where most of you reading this article reside), spawning trout and salmon are the staple meal through late summer and fall. Mammalian prey, meanwhile, includes rabbits, hares, ground squirrels, raccoons, and even deer fawns and beavers.

The tremendous strength of Bald Eagles and their hunting prowess allow them to typically dominate other fish-eaters and scavengers, and have been noted to displace mammals such as Coyotes and foxes. As healthy adults are not preyed on in the wild, they are considered apex predators (residing at the top of the food chain).

While total numbers of Bald Eagles appear to be recovering after substantial declines in the 20th-century (mostly attributed to the pesticide DDT, which caused sterility as well as thin eggs unable to withstand the weight of a brooding adult), humans still remain the largest threat to the species. A study conducted by the National Wildlife Health Center from 1963 to 1984, that assessed the cause of death for all recorded eagles, found that 68% of mortality was human-caused. While this rate is worrisome, the populations seem to be rather resistant, and recent increased efforts to protect the species has resulted in substantial recovery: in 1995, the U.S. Fish and Wildlife Service removed the Bald Eagle from the endangered species list.

So, with all these incredible facts now at hand, you may wish to go see some. How? Well, just visit some local wetlands and you might be fortunate! 

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