The Songs and Singing Behavior of the Red-Eyed Vireo

An audiospectrographic study of some 12,500 songs of Red-eyed Vireos (Vireo olivaceus), from over 46 birds from nine states, provided data on song structure, vocal repertoires, and the birds' use of their repertoires. These songs have one or more syllables, each syllable consisting of one or more abrupt musical slurs. Each bird has a sizeable repertoire of syllable types, each of which may be used alone and/or with one or more other syllables to produce a number of different song types. The song type repertoires of individual birds ranged from 12 to 117 (average, 39.4). There is relatively little sharing of songs and syllable types among individuals and that which occurs is not always in proportion to the proximity of the birds concerned. A bird sings its different song types in a varied sequence, and rarely sings the same song type twice in succession; some types in the repertoire are sung frequently, while others are sung only rarely. No correlation was found between the song types sung, or their sequence, and the observable circumstances under which the songs were sung. Some geographic variation was found in the birds studied, but the significance of this variation is open to question. A Red-eyed Vireo in an early stage of song development has a very large repertoire of syllable types and uses them in many different combinations; as primary song is developed, some syllables and syllable combinations are perfected and others are discarded. It is probably largely a matter of chance what particular syllable and song types remain in the primary repertoire, but birds may tend not to duplicate the song and syllable types of their neighbors.