Acoustical features of song categories of the Adelaide's warbler (Dendroica adelaidae)
Staicer, Cynthia A.
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I identified acoustical features that distinguish the two song categories, A and B, of the Adelaide';s Warbler (Dendroica adelaidae). Like many other wood-warbler species, male Adelaide';s Warblers have functionally structured song repertoires such that A and B song categories are distinguished by common usage among males. The particular song types used in a given category, however, vary greatly among individual males. Therefore, I focused my analysis on acoustical features other than song types. Song categories were distinguished by three major features: (1) the sound energy within a given B song was concentrated into a narrower frequency band, which was shifted about 600 Hz lower than for A songs; (2) the structure of B songs tended to be more complex, as they contained more note types and greater contrast between successive types than did A songs (discriminant function analysis using structural and frequency data correctly classified 85% of songs to category); and (3) the singing behavior associated with B-song sequences was more complex, due to inclusion of a larger number of song types, more frequent switching or alternating between them, and a more rapid rate of song delivery. Overall, the B category appears to represent a more complex and lower frequency signal than the A category. Differences between the two song categories, which parallel data available for other paruline species, should reduce signal ambiguity and are consistent with several nonmutually exclusive functional interpretations: The B-song category, used in intrasexual interactions, might represent a more aggressive signal or might be specialized for carrying motivational information. Females might find the higher-frequency A-song category more appeasing or stimulating. Song categories A and B also might be specialized for traveling different distances, at different times of day, or through different microhabitats.
Staicer, Cynthia A.. 1996. "Acoustical features of song categories of the Adelaide's warbler (Dendroica adelaidae)." Auk 113(4): 771-783.