CONTRAST BETWEEN SUCCESSIVE SONGS AFFECTS THE RESPONSE OF EASTERN MEADOWLARKS TO PLAYBACK

Two playback experiments were conducted to examine the effects of acoustic contrast in sequences of songs on responses of eastern meadowlarks, Sturnella magna. In the first experiment, subjects were played pairs of their own songs that differed in the degree of acoustic contrast. No differences were found between the birds' responses to similar and contrasting song sequences. Moreover, they matched playback equally often following switches between similar or contrasting song types. Thus, individuals recognized even subtle differences in the acoustic properties of their own songs. In the second experiment, some of the same song types were played back to strangers. When composed of unfamiliar songs, sequences of contrasting song types elicited faster and stronger responses than did similar sequences. Following contrasting switches, subjects had a shorter latency to answer the playback, sang more often, switched among their own song types more frequently and had a shorter latency to switch to a new song type. Thus, when unfamiliar song types are involved, switches between contrasting song types appear to be more readily detected by listeners than are switches between similar songs. Because sequences of contrasting songs will be perceived as having greater variety, they may also be stronger stimuli for unfamiliar listeners. These results suggest that eastern meadowlarks agree with our classification of some song types as contrasting and others as similar. © 1990.