Signal Synchrony and Alternation Among Neighbor Males in a Japanese Stream Breeding Treefrog, Buergeria japonica

Abstract

Animals that aggregate in leks to attract mates often time the production of their mating signals against the signals of neighboring conspecifics. Such signal timing usually falls into general patterns within these aggregations, which can be categorized based on the amount of overlap between the signals. In many species, individuals produce signals in an alternating pattern, avoiding signal overlap to reduce interference and increase mate attraction. In contrast, individuals in some species produce signals in synchrony, maximizing overlap and interference. The prevalence and function of signal synchronization is still unknown in many species. Here we examine the call timing strategies of the Ryukyu Kajika frog (Buergeria japonica). Using acoustic playback experiments we characterize a divergence in timing patterns between the two call types in this species, one produced in alternation and one in synchrony. Specifically, male B. japonica responded to playbacks of the first call type (Type I calls) with delayed Type I calls, avoiding overlap with the playbacks. In contrast, males responded to playbacks of the second call type (Type II calls) with synchronized Type II calls, overlapping their calls with the playbacks. Such variation in temporal signaling strategies within a species provides insights into how social and environmental pressures shape signal timings.