Blackburnian Warbler Dendroica fusca
Flight call description A sweet, relatively short, buzzy "tzzd".
Fig.1. Maryland September 29, 1994 (MO).
Bird in flight.
Similar species Generally the sweetest and highest-pitched of the "zeep" group. Louisiana Waterthrush has the same sweetness but is longer. Worm-eating Warbler is nearly as high but is much drier. See Bay-breasted Warbler and "zeep" calls.
Behavior Primarily a nocturnal migrant but engages in redetermined migration. Gives flight call regularly while perched and in flight during the day as well as during nocturnal migration.
Spectrographic description Measured calls (N=13) were 35-66.9 (49.5) mS in duration and in the 6.5-9.7 (7.1-9) kHz frequency range. The frequency track was single-banded (rarely with a faint second band) and was level or slightly rising. It was modulated with 2-3 humps with a spacing of 14.6-18.5 (16.4) mS and a depth of 1.1-2.2 (1.8) kHz. Modulation troughs were typically u-shaped and peaks were frequently leaning to the left.