The acoustic behaviour of the bush cricket Pholidoptera griseoaptera. I. Alternation, synchronism and rivalry between males.

Abstract

ABSTRACT Pholidoptera griseoptera males singing alone or alternating with other males produce short chirps of three or occasionally four syllables (wing movements) lasting about 100 msec, (at 180 C.). Close proximity of singing males may result in rivalry behaviour where chirps lasting up to about 4 sec. may be produced. The long chirp is not usually continuous but has a number of breaks or ‘stutters’. The syllables and syllable rates in the long chirp and short chirp are essentially similar. At the end of a short chirp or of a group of syllables in the long chirp, the syllable rate is decreased, possibly indicating a waning of excitation of the syllable-producing mechanism. Males within hearing range of each other alternate or occasionally synchronize their short chirps. The pattern of this interaction appears to be determined mainly by mutual inhibition between the singing males. Mutual excitation may cause an increase in chirp rate during the interaction. Chirping may be controlled by a pacemaker system which can be inhibited or excited by its various inputs. A long chirp is possibly the result of a high level of excitation of this mechanism. Alternation singing and rivalry behaviour between males may have a territorial significance.