Variation in White-Throated Sparrow Songs

Abstract

ANYONE who has listened carefully to the songs of passerine birds knows that there is regional, local, and often individual variation in the songs of many species, but this variation has been critically studied (e.g., with a sound spectrograph) in relatively few species. Such studies as have been made (e.g., Borror, 1961) indicate that the nature and amount of variation in passerine songs differ greatly in different species. The songs of the White-throated Sparrow (Zonotrichia albicollis) are relatively simple, and much of the variation in these songs is detectible by ear, yet little has been written about song variation in this species. Saunders (1935) and Arlton (1949) describe several variations of White-throat songs, but say little or nothing about the relative incidence of these variations. This paper is based on a study of the recorded songs of 433 Whitethroated Sparrows from seven states of the United States and six provinces of Canada, recorded from 1951 to 1962. Field observations of 278 additional birds in four states and four provinces were used in an examination of the geographic distribution of the major song patterns. Most of the recordings were made by the writers, but we have been able to study the recordings of 29 birds from the collection of Cornell University (mostly recorded by P. P. Kellogg and the late A. A. Allen) and recordings of 61 birds made by J. Bruce Falls of the University of Toronto. We are grateful to Dr. Kellogg and Dr. Falls for the opportunity to examine their recordings. A summary of the birds studied is given in Table 1; the field observations (by Gunn) were made in 1960. Data on the detailed character of the recorded songs (the pitch, length, and character of the notes) were obtained by means of a Vibralyzer sound spectrograph (Borror and Reese, 1953). At least one song of most birds was graphed, and in many cases two or more songs of a given bird were graphed to learn something of the variation in the songs of that bird. The recorded songs not graphed were studied by listening to the recordings played at a reduced speed. We are concerned in this paper with what is usually called the territorial or advertising song; such songs consist of the vocalizations, usually given only by the male and usually more complex in character than the bird's various call notes, which appear to advertise the presence of the male, to attract a female, and/or to repel other males of the same species. We are not concerned with the biological significance of these songs or their variations; a discussion of this subject must await further study.