bird of passage

noun2

1. •
   A migratory bird, especially a passage migrant (“a bird that stops somewhere for a short time during a seasonal migration”).

   • 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; […] — 1863
2. •
   (figurative) Someone passing through a place and only staying for a short time; an itinerant.

   • The musick and entertainments of Bath are over for this season; and all our gay birds of passage have taken their flight to Bristol-vvell, Tunbridge, Brighthelmstone, Scarborough, Harrovvgate, &c. — 1771