The Role of Male Vocal Signals During Male-Male Competition and Female Mate Choice in Greater Prairie-Chickens (Tympanuchus cupido)
In many taxa, vocal communication plays an integral role in aggression, territorial defense, and female choice. The acoustic structure of vocalizations is influenced by physical constraints on the vocalizer, suggesting a potential for discrimination among individuals. In the lek-mating Greater Prairie-Chicken (Tympanuchus cupido), male vocalizations are an integral part of the ritualized display. We investigated whether variation among vocal characteristics of individual male Greater Prairie-Chickens plays a role during female choice and male-male competition. Vocal characteristics varied among males but were fairly consistent for each male, suggesting that vocalizations might be used by prairie-chickens to identify individuals. Female choice was evaluated by comparing characteristics of vocalizations produced by reproductively successful and unsuccessful males, and successful males were found to vocalize at a relatively lower mean frequency. Playbacks of familiar and unfamiliar males were conducted on the lek to assess the role of vocalizations during male-male competition. Males responded to the prairie-chicken treatments by vocalizing at a faster rate and approaching the playback speaker, but they did not respond more strongly to the vocalizations of unfamiliar males than familiar males. Our results suggest that variation is present among the vocalizations of individual male Greater Prairie-Chickens and that this variation could be used by females during mate choice, but signal variation does not appear to be used by males to discriminate among familiar individuals and strangers. However, vocalization elicits an aggressive response in males that hear it, regardless of the individual that has produced it. Vocalization likely functions as a way of announcing that a territory is occupied and defended, but it may also serve as a way of advertising to male or female conspecifics or as a signal that is secondary to other forms of communication.
Biology, Behavioral Sciences, Ecology, vocalization, female choice, individual recognition, male competition, acoustic signaling, grouse, Greater Prairie-Chickens, playback experiment
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