Window on Nature
By Lowell & Kaye Christie, F47246
Fellow birder, writer, and valued friend Jack Wilburn once said, “There is no bird more majestic than the golden eagle.” To that we say, “Amen.” These birds are enormous yet graceful, royal in appearance yet fierce when snatching a meal.
The name golden eagle can be deceiving. When seen from below or on a cloudy day, these birds appear to be dark brown. But in bright sunlight and from the right angle, the backs of their heads and necks are pure gold. Up close you can see their gray, hooked beaks and large, yellow feet bearing talons as long as a man’s hand.
Here’s an easy way to identify these birds that doesn’t rely on the sun: golden eagles have feathers that grow all the way down to their feet, whereas the legs of most eagle species are featherless. Still, recognizing these birds can be tough when they are in the air. One of our favorite sightings was when we were driving on a winding mountain road, looked down, and flying below us was a beautifully illuminated adult golden eagle. Another favorite sighting occurred while we were driving from our home in the foothills of the Sierra Nevada and noticed an enormous bird perched on a telephone pole. Luckily, only a few people live on that road, so we stopped for a closer look at a splendid golden eagle. Yet another reason we love living far from the madding crowd.
Adult golden eagles have an enormous wingspan “” six feet or so “” which allows them to soar on thermals for long periods of time without flapping their wings. Given a nice updraft, they literally can hang in the air.
Bald eagles are huge, but golden eagles are even larger, with the females significantly bigger than the males. Males are 30-1/2 to 35-1/2 inches long, but females range in size from 35-1/2 to 41-1/2 inches in length. That size requires a female’s wingspan to be nearly 10 percent longer than her male counterpart. What’s more, females outweigh males by 40 to 50 percent.
The range of the golden eagle includes North America, Europe, and Asia. In North America, they’re widely distributed across Alaska, Canada, the western United States, and Mexico. Populations in the eastern United States have declined as the human population has increased. Your best bet for finding this eagle in the East is during the winter. Unfortunately, they don’t congregate in large numbers during the winter like bald eagles do, so they are tougher to spot.
Golden eagle populations in Alaska and northern Canada nest and raise their young in the north, then migrate to southern climates where food is more plentiful. Those that live south of the Canadian border stay in their nesting territory year-round. They prefer building their nests into sheer cliff faces or on rocky outcrops, but will, if necessary, settle in the tops of trees. These lofty nest sites insure that the eaglets seldom fall prey to predators.
Young or old, a golden eagle’s diet consists of fox, skunk, rabbit, ground squirrel, crow, pheasant, and, in high country, marmot. Since they are such terrific hunters, they usually leave carrion to the vultures.
You’re probably aware that golden eagles use the same nest year after year. But did you know that most nests are decades, sometimes centuries, old? They need to be repaired occasionally, of course, but seldom are completely replaced. To prepare the nest for the next set of eaglets, the eagle jams new sticks around the outside and prepares a new lining made of grass, lichen, and feathers. With all these additions through the decades, it’s not uncommon for nests to measure five feet high and six feet across.
Golden eagles nearly always mate for life, so both parents are around to share the chick-rearing responsibilities. The female lays one to four (usually two) brown, splotchy eggs. She doesn’t wait until all the eggs are laid before incubating them, so the eaglets often hatch a day or two apart. The mother and father share incubating duties for the 40 to 45 days before the eggs hatch. Once the youngsters emerge, however, the father shoulders the food-finding responsibility while the mother tends to the chicks.
Eaglets weigh only three ounces when they crack out of their eggs. They’ll spend the next 70 days or so eating and growing before they fledge. The youngsters are large enough and strong enough for their first flight in early August. By late September, the youngsters are ready to face life on their own, independent of their parents and siblings.
Staying alive is tough during the first few years of an eagle’s life. Not only do the youngsters learn to catch their own meals and stay out of trouble, but many migrate. Many young birds learn how and where to migrate by imitating their elders, but not golden eagles, since they fly solo. Golden eagles from Alaska and northern Canada must follow their own instincts to migrate south.
Golden eagle attrition is high. A study done in Alaska’s Denali National Park showed that only 10 to 15 percent of the eaglets live to reach sexual maturity at approximately five years of age. Most die from starvation, disease, predation, and electrocution. The good news, however, is that those golden eagles that do survive to maturity may live for 25 to 35 years in the wild.
Overall, the greatest threat to golden eagles in North America is the destruction of native habitats. These changes cause a ripple effect across entire ecosystems, and are likely to have continued detrimental effects on the eagle populations that nest and winter in the western United States.
We can cheerfully report that an estimated 70,000 golden eagles live in Canada and the United States today. Another estimate showed that 125 territorial pairs of golden eagles live in Denali National Park. Of course, because of the bitter winters, those eagles typically spend winter south of the Canadian border.
In California, the slopes and valleys of the Diablo Mountains southeast of San Francisco Bay support the highest known density of golden eagle nesting territories in the world. In one 510-square-mile section of oak savanna near the city of Livermore, at least 44 occupied breeding territories can be found, with a pair of eagles every 5.6 square miles. Why? Because the area offers a combination of open grassland habitats; strong upslope winds funneling from the bay east to the Central Valley; a scattering of oaks suitable for nesting; and an abundance of California ground squirrels for food. These are ideal conditions for this beautiful creature. And if we continue to remember the needs of the golden eagle and other species of predatory birds, we’ll be rewarded with moments of power and beauty soaring through the air.