Geographical Variation in Wood Thrush Song

Abstract

In a comparison of samples of wood thrush song recorded from southern New York State and coastal South Carolina, the following results demonstrate the striking similarity of song in these widely separated areas: (1) Of 25 discrete song types defined for the New York sample, 19 were found in South Carolina, (2) the relative abundances of the different song types were significantly correlated in two samples, and (3) according to a detailed quantitative analysis, the structure of the most common song type was the same in the two samples. Subtle differences did occur between the two samples. Although some of these differences may have been due merely to random sampling error, one difference-the absence of six song types from the South Carolina sample-could not be dismissed in this way. This result indicates that some song types are not widely distributed. Another difference between the two samples had to do specifically with one of the song types absent from South Carolina. In the South Carolina sample were six unclassified songs that, although structurally diverse, all had certain features in common with the missing type and therefore may be related to it by cultural evolution.