“That delay allows them to cool down, and once she reheats them to body temperature, that sets off the biochemical reactions that lead to the development of a chick. Canadian Peregrine Foundation. terrific parents – ever watchful and supplying a constant source of food. At 38-45 Days: Fully feathered except for bits of fluff on top of head and under wings. 35 days old today…they should be flying within a week, I’m watching them more often in the hope of seeing one of them take off. Here are illustrations of their weekly development using photos of peregrines at the University of Pittsburgh’s Cathedral of Learning and the Gulf Tower in Downtown Pittsburgh. document.write(year) // End --> If you wish to use a photo please leave a comment with your request. The youngest chick is obvious because it has more down. peck and nibble on bits of carcass holding it down with Your email address will not be published. All photos are from the 2002 Rochester, New York nest, captured via the Kodak Birdcam and reproduced here with the kind permission of Kodak.