Information cues used in male competition by Tettigonia cantans (Orthoptera: Tettigoniidae)

Abstract

Males of the bush cricket Tettigonia cantans often occur in dense populations in which agonistic, competitive behaviour between singing males is frequently seen. Some of the informational cues that might be used to resolve these competitive interactions have been examined here, the results being drawn from studies of field behaviour and laboratory observations. The cues examined were song frequency (carrier frequency), song intensity, body weight, prior occupation of ‘territory’ and onset of singing activity. Of these the most reliable cue was song frequency; dominant males have songs pitched almost 1 kHz (on average) lower than subordinate males. Song frequency was not related to body size. No consistent relationship was found between song intensity (of the carrier frequency) and body weight, or intensity and dominance, though 63% of dominant males had a louder high-frequency component in their songs. Body size was not related to status though the heaviest males in the population had a higher probability of becoming dominant. Generally dominant males initiated acoustic interactions. The independence of the carrier frequency and body weight, and the relatively low song frequency of T. cantans (compared to other tettigoniid speices of similar size) suggest that sexual selection has acted to depress song frequency in this species.