POLYTERRITORIAL POLYGYNY IN THE
AMERICAN REDSTART
Robert Charles Secunda 1 - 2 and Thomas W. Sherry 1 - 3
Abstract. --The first six cases of bona fide polygyny are described in American Redstarts
{Setophaga ruticilla ), along with associated male song behavior, nesting and parental care, and a case of female-female aggression. Typically, older (than yearling) males sought sec¬
ondary reproductive opportunities by traveling 100-400 m through continuous forest to advertise new territories using "repeat-mode" song, typical of genuinely unmated males; and fed primary nestlings and fledglings more than secondary ones. Estimated frequencies of polygynous mating were 15.8%, 5.3%, and 8.0%, respectively, in 1988, 1989, and 1990
(N = 63 color-banded males under close observation), but additional cases of poly territorial advertisement behavior were noted. Polygyny appears to be a facultative strategy by which males obtain extra reproductive opportunities deceptively, on secondary territories far removed from sites of primary territories and nests. However, we have not ruled out the possibility that secondary females could compensate for reduced parental care by mating with higher quality mates or on better territories than otherwise available. Polygyny may have been facilitated in our study population by a relatively low abundance of males and an unusual abundance of yearlings. Receiv…