Peregrine Falcon is most likely to be confused with Prairie Falcon, Merlin or the rare Gyrfalcon. Of these, the Prairie Falcon has the most similar size and shape, but it's found only in open areas of the West and is less tied to concentrations of shorebirds, ducks, or pigeons. Prairie Falcons are browner than Peregrines, with dark "armpit" patches under their wings. The average Merlin is substantially smaller than a Peregrine Falcon, with a more compact body, shorter wings, and a stockier appearance. They tend to target smaller birds and even dragonflies. Merlins lack the Peregrine's helmeted look and thick mustache or sideburn. The Gyrfalcon is bulkier than a Peregrine Falcon and is very rare in the continental United States. Gyrfalcons can take down larger birds like Herring Gulls or Common Goldeneyes that a Peregrine can’t really handle.