Peregrine Falcons are large falcons with pointed wings, long tails, adults are blue-gray above and barred below. They have dark heads and well-defined masks.
There are other differences in plumage between Prairie and Peregrine Falcons that show in my photos but by using just their heads it is possible to make a quick ID in the field.
The Peregrine Falcon was quite content on its rusty, lofty perch and didn't do anything but turn its head to see what was going on down below it.
Eight years ago today I didn't know that it would be the last time I'd photograph the Burrowing Owl family together and that a juvenile Peregrine Falcon would have a part in that.