Type A (common): rising buzzy trill ending with a separate zip note
Tip: At a distance only the last note may be heard. Play song with lower volume to learn to recognize the zip only.
Type B (less common): 2 or more series of buzzy notes sometimes ending with lower zip note (Morse 1989b, Moldenhauer and Regelski 2020)
Note: Type B song can be confused with cerulean warbler
Moldenhauer, R. R. and D. J. Regelski (2020). Northern Parula (Setophaga americana), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.
Morse, D. H. (1989b). Song patterns of warblers at dawn and dusk. Wilson Bulletin 101:26-35.
Pieplow, Nathan (2017). Peterson Field Guide to Bird Sounds of Eastern North America. Houghton Mifflin Harcourt, Boston, MA.