"How can you tell how old a peregrine falcon is?
Plumage provides an exact age for two groups in October: Juveniles are first year birds, 6 months old, that hatched last spring. Sub-adults are second year birds, 18 months old, with nearly complete adult plumage. Adults — two or more years old — all have the same plumage."
"Juvenile peregrines remain brown-and-cream colored until they are one year old – the time of their first molt. The difference in coloration is an advantage for them because they are easily recognized by adults and not attacked when they pass through established nesting territories."
