Bachman's Sparrow Aimophila aestivalis
Flight call description No known flight call. A high, short, descending "tswp" is given while perched and in short flights during the day (see Discussion).
Fig.1. Florida December 22, 1995 (Daniel F. Lane).
Perched bird.
Examples Diurnal
Similar species Similar to Northern Parula but shorter and higher. See descending seeps.
Behavior Nocturnal migrant. Not known to call in nocturnal migration.
Discussion Based on the behavior of other sparrows, it seems plausible that this call may sometimes be used as a flight call by nocturnal migrants.