Here in Colorado there are many confusing birds of prey. The Red-tailed Hawk alone is a study in frustration when you consider its numerous color morphs. Is that a Harlan’s? A Krider’s? Or is it a western or eastern Red-tailed? Dark or light morph? It’s enough to make your head spin.
Two of the most easily confused raptors are the Prairie Falcon (Falco mexicanus) and the Peregrine Falcon (Falco peregrinus). It doesn’t help that they can sometimes be found in the same habitat (both nest in cliffs). They’re also roughly the same shape and size, though the Peregrine averages slightly larger.
So how to tell them apart? One obvious way is to take a look at the overall color of the bird. The Prairie Falcon is mostly brown on the upperparts with white underparts speckled or streaked lightly with brown. The Prairie Falcon also has distinct brown “mustache” stripes on either side of the bill set off by the extensive white under the eye. Meanwhile, the Peregrine Falcon is mostly dark grey or black above with creamy underparts that are barred. The area around the eye is dark giving it a hooded appearance. Therefore, its “mustache” isn’t as apparent.
All of that is easy to tell when the bird is perched for you to get a good long look, but what if, as is often the case, your only view is of the bird in flight? Characteristic of a falcon, both have pointed wings, so that’s no help. The best clue is to look at the underside of the wing where the “armpit” would be. Is the area dark? Then you have a Prairie. If the area under the wing is fairly uniformly barred instead, with no obvious contrast in color, you have a Peregrine.
Now is a great time to cruise the eastern Colorado grasslands to see some Prairie Falcons, but you’ll have to wait until spring for the Peregrines to come back. I know I can’t wait!