Window on Nature
By Lowell & Kaye Christie, F47246
This national symbol has soared off the Endangered Species List and is now flourishing again.
On June 20, 1872, the American bald eagle was selected as the emblem of the United States. Through the years the bald eagle’s image has graced the backs of many of our coins, from gold pieces through silver dollars, half-dollars, and quarters. You’ll see the image on the back of the dollar bill and on the podium of the U.S. president when he makes a speech. And it’s even getting easier to see a bald eagle in the wild.
On June 28, 2007, the U.S. Department of the Interior removed the American bald eagle from the Endangered Species List. The bald eagle first gained federal protection in 1940 under what was later called the Bald and Golden Eagle Protection Act. After some improvement in the bald eagle’s status, the widespread use of DDT, a synthetic pesticide, after World War II caused the bird’s numbers to plummet, and by 1963 only 417 pairs of nesting bald eagles remained in the lower 48 states. According to the U. S. Fish & Wildlife Service, that number has now grown to 9,789 breeding pairs, a true success story. The bald eagle is still a protected species, however.
Bald eagles are one of our largest birds of prey. Females are slightly larger than the males (this is common among raptors), and the largest of them stand more than 3 feet tall with a wingspan exceeding 7 feet.
A purely American bird, the bald eagle is found only from Alaska to northern Mexico. It is the only “sea eagle” native to North America, and usually is found along coastlines and major lakes and rivers. As you might expect, approximately 80 percent of the bird’s diet is fish, with much of the rest made up of waterfowl, small animals, and carrion.
With eyesight more than four times as sharp as that of a human, the eagle can spot a swimming fish from several hundred feet in the air. Once it sees its prey, the eagle usually goes into a shallow glide and uses its talons to make the capture. As soon as the bird’s foot touches the prey, the talons close and lock in place. The bird is strong enough to lift a fish weighing as much as four pounds, but if the eagle submerges too far into the water, or tackles a fish a bit too large, it uses its massive wings and swims to shore.
One year while we were canoeing on the Colorado River, a bald eagle provided the highlight of our trip. On silent wings, it swooped over our heads and took a fish out of the water about 50 feet in front of our canoe. It then flew to a dead snag and ate its dinner as we quietly floated past.
In this situation, the eagle didn’t seem to move very fast, but that’s not always the case. In level flight the bald eagle can travel approximately 30 miles an hour, but according to the San Diego Zoo, they can power-dive up to 200 miles an hour. They also have been identified soaring at an altitude of 10,000 feet.
The adult bald eagle is easy to recognize, being the only large dark bird in North America with a white head and tail. The head, of course, is not bald, but covered with short white feathers. The head and tail don’t take on their distinctive coloration until the bird reaches sexual maturity, usually in its fifth year.
The juvenile plumage is brown, speckled with white, and the bird can easily be mistaken for a golden eagle. The juvenile bald eagle also starts out with a brownish beak and eyes, both of which turn golden with age.
The young eagle begins life in a nest that may have been used by the same parents for many years. Bald eagles mate for life, and they usually come back to the same spot season after season. If there are tall trees in the area, the nest may be as much as 100 feet above the ground, and each year the couple adds more bulk to the construction.
Since in some cases a nest may be used for decades, it can grow into quite a bulky affair. The bald eagle builds the largest nest of any North American bird, with one source describing a nest 9 feet wide, 20 feet deep, and weighing more than two tons. You can imagine the problem when the weight becomes too much for the supporting branches. But when a nest does fall, the homeless couple normally starts a new structure in the same general location.
The female eagle lays one to three eggs, but depending upon the availability of food, there is often only one surviving chick. The second egg is laid several days after the first, which means the first chick to hatch has a head start. If the oldest chick is a female, it will have an additional size advantage over any male nest-mate, and may end up taking almost all of the food.
Young eagles grow fast, gaining approximately a pound every four or five days. By three weeks they are almost 1 foot tall, and at six weeks almost as large as their parents. By three months the young birds are ready to leave the nest and try out their wings. The first year is the most hazardous for a bald eagle, with only about 50 percent surviving the dangers of life in the wild.
The average lifespan of a bald eagle is between 15 and 20 years, but the oldest known wild bird survived for 39 years. And in the safer environment of captivity, a bald eagle in New York lived to the ripe old age of 48.
If you want to see bald eagles, approximately half of the world’s population can be found in Alaska. Of course, to see them in winter when they congregate in large numbers, you might prefer to stay a bit farther south. Fortunately, there are good viewing locations throughout the United States and Canada.
In this month’s “Baker’s Dozen” column, you’ll find a list of many of the best spots to see wintering bald eagles in the lower 48 states, with locations from the state of Washington all the way to Florida. Join us this winter as we celebrate the return of the eagles.