i Register
In some senses, snowbird is marked as slang, US. Watch for register when choosing this word.
noun
A bird, Junco hyemalis, the dark-eyed junco.
A migratory bird seen primarily in the winter time.
The snow bunting (Plectrophenax nivalis).
A person, usually one who is retired, who travels from a cold climate to a warmer one in the winter; one who overwinters elsewhere.
One who enlists in fall to desert after winter.