Song variation in a population of chestnut-sided warblers (Dendroica pensylvanica): its nature and suggested significance

Abstract

Song variation in a population of D. pensylvanica was studied during 1970-1972 in Hillsboro County, New Hampshire [USA]. Song types (5) which appear to be shared by all males in the local population, were described and were used differentially by the birds. Two accented ending song types were used primarily by undisturbed males located centrally on their territories. Two unaccented ending song types were used in territorial encounters, or when a male was located peripherally on his territory. The 5th type, jumbled song, was used almost exclusively during territorial encounters. There was no evidence of special association of any of the types with male-female interactions. The song types form a graded series of signals, increasing the efficiency of male-male communication by transmitting more precise messages than would be possible with only a single song type.