Subadult

(noun) A bird that has some adult characteristics but is not yet sexually mature. The term subadult usually refers to larger birds such as gulls and raptors that may take several years to reach full maturity and recognizable adult plumage, such as the bald eagle, which will not get the characteristic white hood and tail until it is five years old. Many times, subadults are referred to more specifically by their age, such as first year or second year birds, as determined by their coloration and markings. Subadult birds, while not yet sexually mature, are usually able to fend for themselves and establish their own place in a flock or individual territories.