- Chicks weigh 35–40 g (1.2–1.4 oz.) and are covered with whitish down when they hatch.
- They have about half their feathers by the time they are 30 days old.
- They are almost fully feathered, with patches of down, by day 35.
- Fledged juveniles are the same size and shape as adults but their upperparts vary in colour from slate grey to chocolate brown.
- Their crowns are pale, and they have a dark stripe extending below each eye.
- Underparts are buffy with dark streaks.
- The bill is blue-grey, darker at tip, but by fledging is close to the adult colour.
- The legs and feet are bluish-grey in eastern birds.
- By their second year, Peregrine Falcons are bluish-grey on top, and have a distinctive black facial line, called a malar stripe, extending down from the eye.
- Underparts are pale, with variable amounts of blackish or dark brown spotting and barring.
- The undersides of the wings and tail are barred pale gray and black.
- The legs, feet, eye rings and the base of the beak are yellow; the rest of the bill is black.