Palm Warbler Dendroica palmarum
Flight call description A relatively low-pitched, monotone, whistled "seemp" with a slightly husky quality and typically with an abrupt "p" sound at the end. In diurnal flight, frequently gives a hybrid "ssupk" call, starting with a flight call and slurred into a "chip". See Subspecies.
Fig.1. Maryland September 19, 1994 (MO).
Bird in flight with Boat-tailed Grackle calling in the background.
Similar species One of the more audibly distinctive warbler flight calls. Similar to Prairie Warbler but lower-pitched and with a more abrupt ending. See Blue-winged Warbler and descending seeps.
Behavior Primarily a nocturnal migrant but engages in redetermined migration and limited resumed migration. Gives flight call regularly while perched and in flight during the day, and during nocturnal migration.
Subspecies Flight call of eastern birds (D. p. hypochrysea) may average lower-pitched than that of western birds (D. p. palmarum), but probably much overlap exists.
Spectrographic description Measured calls (N=10) were 35.7-60.9 (48.1) mS in duration and in the 3.6-7 (4.2-6.6) kHz frequency range. The frequency track was single-banded or with a faint upper band. It was either level or slightly descending and often gently downward-arched. There was invariably an abrupt downward hook at the end.