Peregrines are fairly long-winged and long tailed. A medium-sized Falcon, the sized range between a small male and large female can be fairly great. In flight, wing beat and movement patterns are distinctive. Buteos, accipters and harriers flap in series and glide while Falcons wingbeats are steady and uninterrupted. A Peregrine will generally appear long in the wing. Its movements being shallow, fluid, rhythmic and undulating. In regards to similiar species, Merlins are much smaller and lack the malar stripe. Prairie Falcons have dark wing linings and axillars and are slighter looking than a Peregrine. Gyrfalcons are the larger with longer wings that are broader at the base. Other Falcons lack the bold facial markings of the Peregrine.