It is a very big generalization , and some species are exceptions , but generally first summer individuals can only be separated by retained juvenile remiges and rectrices or by moult limits in the greater coverts 這是一個(gè)很概括的看法,且某些鳥種是例外,但一般而言一齡夏羽個(gè)體只能以還留著的幼鳥飛羽和尾羽,或大覆羽的換羽界限來區(qū)分