In Chicago, our adult peregrines will remain in the city throughout winter. Once past the first year hurdle, peregrines may live for another 15-20 years. They will usually begin to breed at around 3 years. Some have been known to nest when they were 1 or 2 years old. We have already learned that peregrines come in different sizes.
Females are larger than males.
The answer is yes. Immatures peregrines have some differences in plumage from their parents. When young peregrines fledge from the nest they are as big as they are going to get. If you are seeing different sizes, remember that is the difference between male and female, not adult and immature. One main difference between the parents and young is in their color and pattern of coloration.