Song Dialects in the Bobolink (Dolichonyx oryzivorus)

Abstract

Songs of 62 male bobolinks from 5 sites in SE North Dakota and 2 in N central Minnesota [USA] were recorded in 1973 and 1974. Spectrographic analysis disclosed a generally high degree of sharing of phrases and song patterns within populations. Very little similarity was noted between populations except at 2 sites less than 1 km apart. At 2 other sites, where recordings were made in successive years, only the 2 dominant song patterns present the 1st year were found during the 2nd year. A male bobolink may acquire his repertoire of 2 song patterns during his 1st breeding season by copying the songs of an older male. Such a dialect system enhances rapid stabilization of the breeding population and is adaptive when individuals must move due to changes in the breeding environment.