While conducting fieldwork on the breeding ecology of grassland birds
at Kennebunk, Maine, we documented the existence of extended flight-so
ngs of Vesper Sparrows (Pooecetes gramineus). In general, we observed
this behavior very infrequently, usually less than three times per bre
eding season. Extended flight-songs were about three times as long as
primary songs and contained elements not typically found in primary so
ngs. Extended flight-songs occurred more frequently late in the breedi
ng season. Within the subfamily Emberizinae, extended flight-songs hav
e now been documented for at least 10 species but their behavioral fun
ction remains unclear.