The male passes prey it has caught to the female in mid-air. Pairs perform courtship flight that includes a mix of aerial acrobatics, precise spirals, and steep dives. During the breeding season, these birds are territorial and nesting pairs are usually more than 1 km (0.62 mi) apart. A pair mates for life and returns to the same nesting spot annually. Peregrine falcons are monogamous breeders. Peregrine falcons are generally silent birds but when near the nest, they usually produce a rasping 'kack-kack-kack-kack' call. Breeding pairs may hunt together and the female often catches larger prey. Peregrines may also surprise and ambush prey on the ground, and in rare cases even pursue the prey on foot. If they miss the initial strike, they will chase their prey in a twisting flight. If their prey is too heavy to carry, peregrines will drop it to the ground and eat it there. Prey is typically struck and captured in mid-air Peregrine falcons strike their prey with a clenched foot, stunning or killing it with the impact, then turn to catch it in mid-air. Once prey is spotted, these hunters begin their stoop, folding back the tail and wings, with feet tucked. Peregrines require open space for hunting and searching for prey either from a high perch or from the air. These birds are active during the day but hunt most often at dawn and dusk when prey are most active. Peregrine falcons are not very social birds outside of the breeding season, they are often seen singly or in pairs. An immature Peregrine falcon is much browner, with streaked, rather than barred, underparts, and has a pale bluish cere and orbital ring.

The upper beak is notched near the tip, an adaptation that enables falcons to kill prey by severing the spinal column at the neck. The cere is yellow, as are the feet, and the beak and claws are black. The top of the head and a 'mustache' along the cheeks are black, contrasting sharply with the pale sides of the neck and white throat. The tail colored like the back but with thin clean bars, is long, narrow, and rounded at the end with a black tip and a white band at the very end. The white to rusty underparts are barred with thin clean bands of dark brown or black. The back and the long pointed wings of the adult Peregrine falcon are usually bluish-black to slate grey with indistinct darker barring the wingtips are black. The male and female of this species have similar markings and plumage but, as with many birds of prey, the female measures up to 30% larger than the male.

Falcon peregrin