Nice question, Bernice (in Mondovi, CA).
At least nine species of temperate zone wood-warblers (representing six genera: Vermivora, Dendroica, Setophaga, Seiurus, Geothlypis, and Wilsonia) have been confirmed as singers based on field studies (Evans Ogden, Neudorf, Pitcher, and Strutchbury, 2003).
Given merely a minority of females sing among the world’s 4,000+ songbird species, what’s the payoff for this vocal behavior? One theory is that female singers may be adopting male-like behavior, especially among older females (Nolan, 1978). Another theory suggests female song results from female-female conflicts occurring in dense populations (Hobson and Sealy, 1990) or may be a function in intra-pair contact (Gilbert and Carroll, 1999).
Among the singing wood-warblers in the U.S., Dunn & Garrett state in Warblers (1997) that Yellow Warbler (ABOVE photo, a female, courtesy of the US Fish & Wildlife Service) song has been documented in at least one population in Manitoba, Canada (Dunn & Garrett, 1997).
Likewise, these two authors suggest in the same field guide that American Redstart females sing sporadically to rarely (if at all).
