The back is slightly darker than in the Tundra Peregrine, but still has bluish-gray tinges, especially on the upperwing coverts and uppertail coverts. The moustache on the Anatum Peregrine is very wide, and the auricular patch is often very small. Immatures have a solid brown crown and forehead, and have a fairly wide moustache, although their auricular patch is often larger than that of adults. They have heavy brown streaks on their cream coloured breast and belly, and have small buffy edges to the feathers on their back. The Peale's Peregrine is the largest and darkest of the North American subspecies.
Adults have dark dense barring across the belly, and even to some degree over the breast.
The moustache is narrower than that of the Anatum, but wider than that of the Tundra, and unlike the other subspecies, the Peale's has dark streaking in the auricular patch. Immatures have very broad dark streaking on their breast and belly, making their underparts appear almost solid dark. Their back is a dark brown-gray, and the feathers usually have no buffy edges. Both sexes give the same call, but males tend to sound somewhat wheezy and high-pitched, while females are more grating and coarse sounding. This call is usually given as a response to disturbance.