To conduct the study, researchers recorded a collection of songs from 615 adult male swamp sparrows from six densely populated areas across the northeastern United States. They dissected each bird’s song repertoire, identifying only 160 different syllable types within all the recorded sample. Most swamp swallows sang the same tunes, using the same common syllables, but there were a few rare types in each population, just as there are variations in human oral histories over time.
Other bird and animal species may also be capable of similar feats, the researchers say. Even animals with relatively small brains can have long-lasting traditions.