Ferruginous Hawk — My, What Dainty Feet You Have!

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About a week ago I was able to capture an image of a Ferruginous Hawk just as it lifted off from its perch.  It’s a nice image, really showing off the bird.  Notice the red “leggings” on this individual that extend all the way down to its feet.  Those leggings are an identifying characteristic  of a Ferruginous Hawk.  Only one other North American buteo, the Rough-legged Hawk, has “leggings,” and the Ferruginous Hawk’s rusty “leggings” are uniquely colored.

There is one other unique anatomical feature of a Ferruginous Hawk that this image shows off well, and that is the bird’s relatively small feet.  They are positively dainty in comparison to the hawk’s overall size.  Other buteos, such as Red-tailed Hawks, have proportionately much larger feet.   Other non-buteo raptors, including many owls, have feet that are positively gigantic in comparison to the birds’ size.  Many raptors use their oversize feet to seize and crush their prey.

So, what gives?  Why does North America’s biggest hawk have such relatively little feet?  It’s an adaptation that helps Ferruginous Hawks hunt successfully.

And, it’s also a bit of a paradox.  As is the case with many other buteos, Ferruginous Hawks use their feet to seize and immobilize prey.  So, wouldn’t bigger mitts serve these birds better in doing that job?

But, consider Ferruginous Hawks’ preferred prey and their hunting style.  These hawks specialize in ground-dwelling rodents such as ground squirrels and prairie dogs.  They’ve developed a unique and successful hunting technique for capturing these animals.  A Ferruginous Hawk will sometimes perch patiently and silently on the ground adjacent to a rodent’s burrow.  At the slightest movement by a rodent close to the surface the hawk will plunge a  foot into the burrow and use its talons to snag the rodent.  The hawk then yanks its prey out of the ground and dispatches it.

Small feet give this hawk an advantage because they enable it to reach down into narrow tunnels.  So, in this case, as counterintuitive as it appears to be, little feet actually help the Ferruginous Hawk capture prey.

Image made with a Canon 5Div, 400mm f4 DO II lens+1.4x telextender, M setting (auto ISO), ISO 800, f6.3 @ 1/2000.