A bird it its first autumn, 2-5 months old. It refers to its age and not its plumage .
An age category usually referring to the plumage following that of a juvenile bird, usually gained through a partial or complete (in some species) moult in late summer/autumn of the 1st calendar year and is worn until the next spring of the 2nd calendar year .
An age category usually referring to the plumage worn at the approximate age of one year and attained in late winter/spring through partial or complete moult from 1st winter plumage; worn into the next moult usually in late summer/autumn of the same year, replaced with the 2nd winter plumage .
A complete or partial moult in late summer of the 2nd calendar year and worn until the next moult, it is followed by the 1st-summer plumage 
|This article is part of Project Glossary, a All Birds project that aims to write comprehensive articles on each term related to animals.|