snowbird

Short definition from Wiktionary

Noun

1. 1
   A bird, Junco hyemalis, the dark-eyed junco.
2. 2
   A bird seen primarily in the winter time.
3. 3
   The snow bunting (Plectrophenax nivalis).
4. 4
   A person, usually one who is retired, who travels from a cold climate to a warmer one in the winter; one who overwinters elsewhere.
5. 5
   One who enlists in fall to desert after winter.
6. 6
   Someone who uses cocaine illicitly.