bird of passage

After Middle French oiseau de passage.

bird of passage (plural birds of passage)

1. A migratory bird, especially a passage migrant.
   • 1863, Sheridan Le Fanu, The House by the Churchyard

     And now the ladies, with their gay plumage, have flown away like foreign birds of passage, and the jolly old priests of Bacchus, in the parlour, make their libations of claret; and the young fellows, after a while, seeing a gathering of painted fans, and rustling hoops, and fluttering laces, upon the lawn […]

2. (figuratively) Someone passing through; an itinerant.

• (bird): migrant, migratory bird