Evidence for "floaters" in the American Redstart

TitleEvidence for "floaters" in the American Redstart
Publication TypeJournal Article
Year of Publication1974
AuthorsHowe HF
JournalJack Pine Warbler

Male American Redstarts (Setophaga ruticilla) in their first breeding season retain female-like plumage and are excluded from apparently "optimal" breeding habitats by adult males. ...These data suggest that both adult and first-year males are "floaters" in one area. This is surprising in view of the evidence that first-year males are excluded from some habitats by adult males since some yearlings do breed. ...One would predict that adult males would displace or exclude yearling males from habitats in which there is a chance of raising young. While it is possible that it is adaptive for some adult males to remain unmated until a chance opening occurs in "good" habitat, the replacement of 4 adult males in presumably superior habitat by 4 yearling males in the presence of a floating population of adult males provides circumstantial evidence that some first-year males resist displacement or exclusion by adults.