July 2014 – Arizona’s Other Hawk



But they aren’t the only big hawks in town. In Arizona, there’s actually one bigger than either, a bird considered the largest hawk in North America, in fact. He’s big, strong, and beautiful to behold, yet we never hear anything about him. Harris’ hawks are local celebrities, and red-tailed hawks are the one raptor that everyone knows and nearly everyone has seen, but who, or what, is the ferruginous hawk?

Despite their size, ferruginous hawks are rather inconspicuous fellows, and they sometimes get misidentified as particularly large red-tailed hawks sitting on telephone poles. Their dominant coloring is incorporated into their name: “ferruginous” derives from the root word ferrous, a reference to iron, since their head, back, and wings are rust in color. Their chest and the undersides of their wings are a much lighter white, which is largely why they often get mistaken for red-tailed hawks, since that bird, too, is darker on the back and light in the front. But the ferruginous hawk takes everything that makes the red-tail a powerhouse and amps it up even more. Ferruginous hawks have a few inches in length and wingspan over their cousins, and are usually heavier-bodied, sometimes weighing almost twice as much. Like the red-tail, ferruginous hawks are members of the buteo family, a group of large, broad-winged hawks that are found all over North America. While red-tails have managed to carve out a niche for themselves in just about every kind of terrain, including the urban variety, ferruginous hawks have traditionally been birds of wide-open spaces, where large game like prairie dogs and jackrabbits are in abundance. Once upon a time, the American Prairie was their bread and butter, and according to Cornell University, their nesting habits were closely tied in to the once-prolific herds of American bison. Debris from the herds, whether torn wool or bones from the dead, would be used to construct their nesting sites. The wholesale slaughter of bison herds in the nineteenth century forced ferruginous hawks to change their instinctual habits, but despite the loss of their prairie compatriots, they are still found throughout the western United States, from the open expanses of Midwestern farmland to our own Desert Southwest.

It’s fitting that their very name incorporates a strong reference to iron, because their hunting technique is akin to that of a flying anvil. When you’re that heavy and powerful, there’s not much need for subtlety, so they hunt by picking a conspicuous perch and simply waiting until something edible presents itself, whether it be a prairie dog, a snake, or a jackrabbit. Then the anvil takes flight, with all the impact force that metaphor entails. Though they lack the agility of smaller, lighter birds, they are still both swift and skilled on the wing. Their size gives them tremendous power behind their wings, which provides an advantage both in pursuit of prey, and in flight from predators. Though not threatened by much, the ferruginous hawk does sometimes run afoul of golden eagles, because even though the eagle has an obvious size advantage, they’re both big enough to compete for the same food sources, and in the natural world, competition quickly breeds enmity. Yet for every other bird of prey, they are a stoic predator not to be trifled with.

Ferruginous hawks don’t get as much attention from the public simply because they’re content to go about their business without flashy gimmicks. They aren’t as acrobatic as falcons, mysterious as owls, big as eagles, or widespread as red-tails. They don’t have the novelty of being avian pack hunters like our Harris’ hawks. They do just one thing, and do it well: survive. Actually, they do have one thing that their fellow buteos, and in fact most other raptors, don’t: pants. Whereas most birds of prey have bare legs, ferruginous hawks have a thick, healthy covering of feathers down to their feet, similar to an eagle. So the next time you think you see a red-tailed hawk, take a closer look at its legs: our unsung hero will be the one who looks like he’s wearing a comfortable pair of brownish slacks. And if you do spot a hawk, rusty on the back and white in front, with feathers down to his feet, take a second to appreciate him, and a second longer to watch; it’s not every day that you come across one of the great hunters of the West, and even rarer that you get to see an anvil take flight.

Sources: http://www.allaboutbirds.org/guide/Ferruginous_Hawk/lifehistory

1 Comment

One Response to July 2014 – Arizona’s Other Hawk

  1. Carol Marshall says:

    Greg, I like your analogy of the anvil and the ferruginous as well as your ID clue about the “pants.” Good stuff.

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