2013 August – A Tale of Two Eagles

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2013AugNN_Greg-AZ_Bald_soars_overhead

Eagles are bigger and stronger than those other raptors, but what really makes them unique? They’ve been creatures of inspiration since the dawn of humanity, but what makes an eagle an eagle? What makes these birds worthy of being national symbols or the top of their food chain?

The story of these two mighty raptors begins in the same place, but diverges quickly. First, the basics: what is an eagle? An eagle is classified by its size: anatomically, they’re not that different from hawks. The disparity, though, is definitely dramatic enough to warrant their own classification beyond simply being big hawks. The red-tailed hawk, a genuine example of a big hawk, might weigh in at three pounds or so. Remember that all birds weigh in light: evolutionary adaptations like air sacs and hollow bone structures developed to keep them as unencumbered as possible, in order to make flight feasible. Raptors are far stronger than their weight suggests; that three-pound hawk has a four-foot wingspan and a grip with its feet so powerful that a strong man would struggle (and quite possibly fail) to pry it apart. That is the red-tailed hawk, and it is impressive. To get an idea of the golden eagle’s raw force, increase that three-pound frame to twelve or thirteen, extend the four-foot wingspan out to seven, and add in a literally crushing amount of foot force. Raptors typically have the ability to “ratchet” their toes into a clenched position, which is how they maintain such an unflinching grip. But while the mechanics are the same, the golden eagle’s vastly superior size enables it to tackle much larger game. Both the golden eagle and the red-tailed hawk may catch jackrabbits; while jacks area at the upper limit of size for red-tails, however, golden eagles have been observed hunting and killing sheep, deer, coyotes, mountain goats, seals, and other large mammals that would have no other reason to watch the sky if not for this soaring predator.

The golden eagle, then, is much like a hawk, in the same way that a dump truck follows in the spirit of a pickup. Like the bald eagle, its majesty has also endeared it to the great nations and leaders of human history. Closest to home, the golden eagle has its own spot, front and center, on the Mexican flag. European variants have long been the ideal royal or imperial standard, and the eagle busts carried into battle by the legions of ancient Rome were considered so sacred that to lose one to an enemy was the ultimate disgrace. It’s no wonder that a creature so completely dominant in its element, and nearly immune to predation because of its gift of flight, would be so idolized by kings, emperors, and more recently, presidents.

The bald eagle might be one of the most famous birds in the world because of its association with the United States. In 1782, the American Congress selected it as the fledgling nation’s national symbol. It is, after all, not only majestic but unique, and whereas the golden eagle has its equivalents in the Old World, the bald eagle is distinctly, well, North American. Yet Benjamin Franklin, one of the most esteemed of our Founding Fathers, argued against it. Why? The bald eagle, according to Cornell University’s ornithology department, “captures its own prey only as a last resort.” It would much rather find an unattended carcass or steal a meal from another animal than catch one itself. These less-than-noble traits are why Mr. Franklin lobbied on behalf of a bird he thought much more industrious, the wild turkey. Obviously, the bald eagle won the day.

The bald eagle is second only to the California condor in terms of size when it comes to American raptors. The idea of it lazily plucking away some smaller hunter’s hard-earned fish doesn’t sound terribly majestic, but it seems much more logical when placed beside the actions of other apex predators. Lions, for instance, are very quick to steal prey from smaller predators; it’s simply a perk of being king. And the bald eagle is king. While the golden eagle represents a more classical approach to hunting than the bald eagle does, the latter prefers a watery realm, and its propensity for fishing separates it from traditional birds of prey. It can and will hunt on land when it has to; its size in comparison to its neighbors simply allows it to take what it needs from lesser hunters, conserving energy, and since the conservation of energy is the key to survival, it’s very hard to fault it.

The bald eagle has stood as a worthy counterpart to the golden eagle, and bald eagle iconography has become as synonymous with the New World as the golden is with the Old. Both birds, through everything they do, through every spread of their wings, through every flight, every dive, and yes, every hunt, give answers to why eagles have fascinated and inspired humankind since the first time we looked up.

Even at a glance, they show us why eagles stand apart.

Sources:
http://bna.birds.cornell.edu/bna/species/684/articles/foodhabits
http://bna.birds.cornell.edu/bna/species/506/articles/introduction
http://bna.birds.cornell.edu/bna/species/506/articles/characteristics

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