Peregrine Falcons (Falco peregrinus) are large and powerful birds of prey which are at the top of the food chain in London. Females, known as Falcons, are Crow sized birds; they have long, broad, pointed wings and a relatively short tail. Males, known as Tiercels are exactly the same but up to a 1/3 again smaller than females. Both are blue /slate-grey above, blackish head with an obvious black 'moustache' that contrasts with its white face. Adult under parts are white with fine barring. Feet are a prominent yellow and appear huge in relation to the bird’s size.
Juvenile peregrines are very similar other than that the upperparts specifically, and lower parts have a brown tone to them with the breast and lower parts streaked rather than barred. Legs also are a duller yellow.