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MACROSCOPE

Beauty Is Only Feather Deep

Was the bald eagle really the best choice of national symbol? A closer look at the habits and evolutionary lineage of this American icon casts doubt

Catherine Raven

Tinker, Tailor, Soldier, Sailor . . .

For the bald eagle, ospreys are a reliable source of nourishment; for me, they're a reliable source of entertainment. Seeking such enjoyment, I sometimes slip down to the Yellowstone River near my home, one of many places where there is always an osprey. The last time I tried this, I didn't have to wait long before one shot like an arrow through the fall poplars. Skimming the water, black racing stripe flashing across its cheek, the bird plunged head first into the river, rose, banked elegantly and circled around to make another dive, this time rising with a trout. Not a trivial accomplishment.

For birds, aquatic predation is a difficult skill to master. Of the various species of large flesh-eating birds in North America, only two are aquatic: the bald eagle and the osprey. Nature clearly gave the latter better equipment. The osprey's barbed feet easily grab fish; its oily feathers resist wetting; sealing nostrils prevent water inhalation; translucent eyelids facilitate underwater vision; and black eye stripes minimize water glare. More significant, the osprey's talons turn backward, so that after it strikes a fish broadside and lifts it out of the water, the bird can turn the catch to face forward, making the load more aerodynamic. No other raptor uses this trick. Bald eagles are far less adept fishers overall, which is perhaps why they favor salmon runs where dead red fish, floating or beached, provide an effortless meal.

So baldies can't match the osprey in an aquatic habitat. Put them on land, and they'll fare even worse against the golden eagle. Not surprisingly, Lewis ended his honeymoon with the bald eagle when he began an affair with the "most beautiful of all eagles in America," the golden, America's only true eagle, whose feathers adorned the headdress of almost every Plains Indian chief. Baldies may successfully steal from the much smaller osprey, but never from the golden, a bird of equal size. Whether bringing down their own prey or feeding on dead or wounded animals, golden eagles rule. Lewis, for one, noted that on the golden eagle's approach "all leave the carcass instantly on which they were feeding." Interested in confirming Lewis's observations, I've hung out near carcasses. It's good enough entertainment that I'm willing to wake up before dawn and return to a scene repeatedly for several days watching until the play is over. Lewis was right: The two eagles enjoy strikingly different roles—the golden one feeds, the bald one cowers.




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