Songs of the Fox Sparrow. II. Intra- and Interpopulation Variation

Abstract

Melospiza and Passerella have been considered congeneric by taxonomists under the name Passerella (Linsdale 1928a, b, Grinnell and Miller 1944, Paynter 1964, Mayr and Short 1970). Paynter (1964) and Mayr and Short (1970) suggested further that this enlarged genus may be most appropriately considered congeneric with Zonotrichia. Many aspects of the vocal behavior of species presently assigned to Melospiza and Zonotrichia (A.O.U. 1957) have been thoroughly studied (for a literature review see Baptista 1975, Martin 1976, 1977). Knowledge gained from studies of species in these genera has been important to our understanding of concepts dealing with geographic variation in behavior, dialects, local gene pool adaptation, and function of avian song (e.g., Mulligan 1966, Harris and Lemon 1974; Handford and Nottebohm 1976; Marler and Tamura 1964, Nottebohm 1969, 1972, 1975; Baker 1975; Hinde 1969, respectively). Given the close phylogenetic relationship of Zonotrichia and Melospiza to the monotypic Passerella, study of Fox Sparrow (Passerella iliaca) vocal behavior should yield valuable insights into our understanding of bird song and this taxonomic group. With such interrelationships and Linsdale's (1928a) suggestion that there might be a correlation between the geographic morphological variation in Fox Sparrows and variation in their vocal behavior, I have studied: (1) how songs of individual Fox Sparrows are structured; (2) how the structure of song compares with that of species in Melospiza and Zonotrichia; (3) how singing behavior is organized; (4) the significance of song in Fox Sparrows; and (5) the extent, if any, of variation in song structure within and among populations. Earlier, I (1976, 1977) demonstrated that the structure of the syllable-types which compose songs of individual Fox Sparrows in Utah and Idaho is most similar to the com-