TYPE I AND II SONGS OF TOWNSEND’S WARBLERS IN OREGON AND WASHINGTON

Abstract

Songs of four populations of Townsend’s Warbler (Setophaga townsendi) studied in Oregon and Washington were of two types. Each population had one song-type with one song that was used early in the breeding season (type I) and a different song-type with one song delivered pre-dawn after pairing, during territorial contests, and often with chip-like call notes (type II). Both types were sung after dawn. Type I songs differed markedly from population to population. The boundaries between songs of adjacent populations were sharp, indicating a system of dialects, unlike many wood-warblers. In contrast, type II songs of all populations were recognizably similar.