alternate plumage

noun

, Ornithology.

1. (of birds having more than one plumage in their cycle of molts) the plumage of the second molt, usually brighter than the basic plumage.

Example Sentences

“They talk about ‘I think this is a worn alternate plumage of a second year whatever Iceland Gull which really looks a whole lot like a Herring Gull’.

From The Guardian