211119-outdoors-zaenger

Bald eagles perch in a tree near the open waters of Blue Mesa Reservoir. Look for them there or near the town of Ridgway and Ridgway State Park. Be sure to have your pass to the state park if you go in. (Courtesy photo/National Park Service)

Rummaging through a worn cedar chest recently, I came across an old T-shirt from Yellowstone National Park. An artistic rendering of a bald eagle is on the front, top feathers ruffled, beak in a smirk and words proclaiming, “Bald is Beautiful.”

Well ... maybe some expressions are better left alone.

National leaders in the American Revolution were unable to agree on a symbol, but by 1782 the bald eagle came forward because it represented freedom and strength.

Back at the cedar chest, my mind drifted back to a time on Lake Powell in the late 1980s. Rangers there made January trips out on the lake to count birds living near the waters behind Glen Canyon Dam.

The birds gather together in winter around open water, which helps them survive the cold season when prey species become scarce. The days were long, even though the amount of winter daylight was reduced.

Our group had been skunked nearly all day, but near the mouth of the San Juan River, there in the eastern sky was a group of 15 to 20 eagles soaring like C-130 military planes. They were mostly silhouetted against the cobalt winter sky, dynamic in their kettling flight, rising on the thermal updrafts to the heights above.

I had not seen a bald eagle before.

Most of us are familiar with scenes of a large eagle flying low over a lake or river; think about that C-130 plane again.

The profile of a huge bird on a shallow glide just above the water is astonishing. Like landing gear, the feet lower down under the body of feathers and stretch out. The talons flex forward, and in an instant snatch a fish out of the water.

The science of eagles’ eyes (and birds of prey in general) transcends human understanding of vision that feeds our notion of dominion. Compare the eye of an eagle to that of a human and you’ll find they are the same size. But relative to their skull and brain, it’s significantly larger.

The iris in an eagle eye is composed of striated muscle, stronger tissues and under its voluntary control.

The human iris is made up of smooth muscle. Smooth muscles are usually found in the stomach, intestines, and so on, and are not under our control. Try as you might, you can’t intentionally change the diameter of your pupil with your iris muscles.

The eagle iris works in tandem with the ciliary muscle which surrounds the eye. Together, they add or release pressure on the fluid in the eye to flex the lens. With that small but essential strength, they can focus easily on distant objects.

Balds can spot small rodents and fish from as far as 2 miles away.

While their eyes give eagles a sense of command, almost none of that matters in the winter. Bald eagles gather around bodies of open water in western Colorado; they arrive at Blue Mesa Lake, Ridgway Reservoir, and along rivers in early November.

Sources of food dwindle in the cold season. Balds are pretty happy to scavenge for nearly anything, and they are not above practicing piracy if another bird has something that looks appetizing.

Roadkill on the highways can help all predators out. It’s unfortunate that accidents happen so often to drivers on U.S. 550 near Ridgway and the lake, but these mishaps sustain wild populations when finding food is tough.

Although protection of migratory birds began early in the last century, enough of a drop in bald eagle numbers was evident that Congress passed the Bald Eagle Protection Act in 1940. Survival became more than a wintertime concern, even as National Audubon Society groups made Christmas bird counts tracking the decline.

There is a success story here. Beginning in the 1960s (when bald eagles were placed on the Endangered Species List), efforts to bring back eagle populations increased. Survival for a group of animals or for an individual species appears to go beyond simply who is strong enough.

Bald eagles were taken off the list in 2007; their populations have rebounded. It’s cold in the early morning now, but go outside anyway. Go out along the rivers, go out along the reservoirs, go out and look in the open tree branches along the shorelines.

The leaves have fallen, so bald eagles are easier to spot. Take binoculars and look for their bleached white heads. They are beautiful. Look not only for the power they have to survive the winter, but the influence they can have in the way that we see the world.

Paul Zaenger is a retired National Park Service supervisory park ranger from the National Park Service. Black Canyon of the Gunnison National Park, Mount Rushmore National Memorial, Glen Canyon National Recreation Area are among his park assignments. He can be reached at zae@bresnan.net.

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