Bird Lore: Bald Eagle

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If Ben Franklin had had his way, the Wild Turkey would have become the symbol of the United States and, perhaps, we would be feasting on goose or duck at Thanksgiving. But in 1782, the new nation designated the Bald Eagle as its emblem, despite Franklin disparaging the bird as a pirate and coward, and accusing it of bad moral character. Ben was referring to the eagle’s tendency to snatch prey away from smaller avian hunters and to permit itself to be chased away by smaller birds.

The Bald Eagle is abundant in Western Washington and Edmonds usually hosts two families each year. There are plenty of opportunities to see adults and younger birds along the waterfront, the Bowl, and other neighborhoods of Edmonds. Typically it is found close to water where prey is abundant, including Florida swamps, conifer forest edges in Southeast Alaska, treeless Aleutian Islands, and Arizona desert rivers. Large concentrations can be found wintering along rivers such as the upper Skagit.

Many species of fish form the centerpiece of the Bald Eagle diet. It also eats a wide variety of foods, depending on availability. Other food sources include birds, reptiles, amphibians, invertebrates such as crabs, and mammals such as muskrats and rabbits. It will take prey live, fresh or as carrion. It is known to gorge on food and then spend several days digesting it. The Bald Eagle can also survive fasting for several days or even weeks.

A courtship ritual, known as the death spiral, can be thrilling to witness. The pair lock talons in mid-air and then cartwheel downward, separating just before reaching the ground. If you have never seen it, this short YouTube video captures the spiral. The unnecessary background music is loud so you might want to mute your device.

The Bald Eagle first breeds at 4-5 years of age and may mate for life. The nest site is usually in a tall tree, above the surrounding forest canopy for easy flight access and good visibility. In treeless areas such as the Aleutian Islands, the nest may be on the ground. In many parts of the western U.S., the nest may be on a cliff or even on a cactus. It is one of the largest of all bird nests, typically 5-6 feet in diameter and 2-4 feet tall. Ohio hosted one of the largest known nests. It weighed nearly two metric tons and was used for 34 years, until the tree blew down. The pair weave together sticks and fill the cracks with softer materials such grass or moss. The inside of the nest is lined with softer materials. A nest can take up to three months to build and may be re-used for many years.

The two eggs are incubated by both adults for 34-36 days. One parent remains with the young for their first two weeks of life. Both adults bring prey to the nest, tear it into small pieces, and feed it directly to the young. After three to six weeks, the eaglets begin picking at food dropped in the nest. When prey is scarce, only the largest of the young will survive. Age at first flight is about 10-12 weeks.

Many coastal and southern adults are permanent residents. Birds from the far northern interior migrate south in winter. Immature birds from Florida may migrate as far north as Canada during their first summer.

Adult Bald Eagles are not sexually dimorphic, meaning they all look the same. When a pair is together, the smaller bird is the male. The oldest wild Bald Eagle of record was at least 38 when it was hit and killed by a car in New York in 2015. It had been banded in that state in 1977. A group of any eagles has a number of collective nouns. They include aerie, convocation, jubilee, soar, and tower of eagles.

The Bald Eagle was once endangered by hunting and pesticides, particularly DDT. It is now a conservation success story. It was removed from the Endangered Species list in 2007, but there are continuing threats that require action. One is lead poisoning that occurs when eagles eat prey that contains lead shot from hunter ammunition. Development- related destruction of shoreline habitats used for nesting, roosting, perching, and foraging is an ongoing problem. Some birds continue to die from collisions with motor vehicles and stationary structures. Oil spills that pollute marine environments also lead to eagle deaths. The Bald Eagle is now a U.S.-Canada Stewardship Species. The estimate of the global population today is about 250,000, without about 88 percent spending some part of the year in the U.S.

You can listen to the calls of a Bald Eagle here: https://www.xeno-canto.org/344281.

— By Carol Riddell

Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.

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