On what occasion is it customary to sing "Las golondrinas"?

“Las golondrinas” (The Swallows) is Mexico’s traditional farewell song, sung when someone leaves: at going-away parties, retirements, graduations, and other goodbyes. The swallow, a migratory bird that departs and returns with the seasons, gives the song its bittersweet image of parting.

Don’t confuse it with “Las mañanitas”, which is the traditional song for birthdays and saint’s days.