The sympatry of three congeneric sparrow species; namely, the Song, Lincoln, and Fox Sparrows in the Jackson Hole area is a unique circumstance in the distribution of this group. Elsewhere they are separated by habitat if not considerable distance, but these species breed together. The Fox and Song Sparrow were observed actually defending interspecific territories. The study conducted during a period of four days in early June was preliminary and was aimed mainly at obtaining a collection of Song Sparrow vocalizations as part of a larger study of the same throughout most of the geographic range of this species. There was question here of the variation which might be found in certain stereotyped calls, since the possibility existed that those used for territorial defense might show character displacement in areas of close sympatry with conceneric species. Project Number 150.
"Comparative Studies of Song Sparrow Vocalizations,"
Jackson Hole Research Station Annual Report: Vol. 1967
, Article 11.
Available at: https://repository.uwyo.edu/jhrs_reports/vol1967/iss1/11