Chickadee Essay

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AN APPRAISAL THE SONGOF THE OF BLACK-CAPPED CHICKADEE KEITH L. DIXON AND RAYMOND A. STEFANSKI T HE songs of most species of birds are distinguished from call notes by 1939:73-74; con- the restriction of the former to one sex, and by the differences in the 1961:15). Song usually is confined to the mating season, and is territory. The vocalization (Parus atricapillus) 1A). This functions served by the two classes of sounds (Tinbergen, associated with occupancy of a breeding often is transliterated Thorpe, sidered to be the song of the Black-capped Chickadee as fee-bee or phoebe. The usual form is a sequence of two pure, whistle-like notes, the second lower in pitch (Fig. vocalization is categorized as a song according to Tinbergen’ s definition “ . . . those loud sounds that are given by birds of one sex especially at the beginning of the reproductive period.” The restriction of loud singing to males during the breeding season, and the manner of delivery, as described by Bradford Torrey (quoted by Tyler, 1946)) support this view. In other respects this vocalization of the Black-capped Chickadee does not conform to the concept of “advertising” Bremond (1963) song as it is exemplified by other from an 1884:135; passerines. The phoebe song is not complex in its physical structure, as would require, and it is not delivered regularly the breeding season (Odum, exposed perch by males during Saunders, 1947), and their 1941:327). These notes are not restricted to the breeding season (Bicknell, functions may differ with the seasons. This unique song clearly warranted further study, some aspects of which we were able to pursue as a facet of a population study. METHODS Observations of behavior associated with singing were made in a population of color-banded chickadees whose nesting progress was known (Stefanski, 1967). Approximately 400
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