The influence of age and size on temporal mate signalling behaviour

I investigated how male size, condition and age influence both time spent c alling and how signals are apportioned throughout the night (i.e. temporal calling pattern) in the Texas field cricket, Gryllus integer. I quantified male calling time and temporal calling pattern using an electronic apparatu s that continuously monitored male calling/noncalling behaviour throughout the night. Male condition, measured using the residuals from an allometric regression of male mass on overall body size, did not explain any variation in either time spent calling or temporal calling pattern. However, some in trapopulation variation in time spent calling and temporal calling pattern was explained by differences in male size and age. Large males called more often than small males. Young and very old adult males called significantly less often than middle-age males. As males aged they initiated calling ear lier in the evening, probably increasing their susceptibility to parasitism by the tachinid parasitoid Ormia ochracea. Overall, age and size differenc es explained 10-40% of signalling variation in male G. integer. (C) 2000 Th e Association for the Study of Animal Behaviour.