Chestnut-sided Warbler Dendroica pensylvanica
Flight call description A low, finely buzzy "ziiih" or "dzzew". Diurnal flight calls are typically even-pitched, while nocturnal flight calls tend to be descending or downward-arched. Some birds in morning flight may give distinctly rising calls.
Fig.1. Maryland September 10, 1994 (MO).
Bird in flight.
Similar species Most similar to Hooded Warbler but averages longer. Calls are either monotone, descending, or arched downward, whereas Hooded's typically is arched upward. This distinction is more pronounced in nocturnal flight calls. See buzz calls.
Behavior Primarily a nocturnal migrant but engages in redetermined migration. Gives flight call regularly while perched and in flight during the day and during nocturnal migration.
Spectrographic description Measured calls (N=10) were 57.7-68.8 (65.8) mS in duration and in the 5-8 (6.1-7.3) kHz frequency range. The frequency track was evenly modulated with a spacing of 5.5-7.1 (6.5) mS between humps and a depth of 0.5-1 (0.7) kHz. The slope of the call was variable.