Use and characteristics of two singing modes in Pine Warblers

Abstract

Abstract North American wood-warblers (Parulidae) are well known for exhibiting two distinct singing modes: first category song, in which a single song type is sung repeatedly, usually before dawn, and second category song, in which several song types are sung in irregular sequence. Studies suggest that first category song types have higher performance characteristics and that second category song types are shared preferentially among territorial neighbors. Here we present the first formal description of two-category singing in the Pine Warbler (Setophaga pinus). Similar to other species in the genus Setophaga, Pine Warblers produce second category song before dawn and first category song primarily during daylight hours. First category songs also had significantly higher trill rates, suggesting that they are more challenging to perform. Unlike many congeners, however, Pine Warblers regularly alternate between first and second category singing throughout the day, and first category song types often appear ...