Intersexual dynamics mediate the expression of satellite mating tactics: unattractive males and parallel preferences

Abstract

Male green treefrogs, Hyla cinerea, attract both potential mates and satellite males with their advertisement calls. Males using the satellite mating tactic position themselves silently near a calling male and attempt to intercept females attracted to the caller. Although use of conditional mating strategies may result from competition among males, few studies have considered the importance of female mate-choice preferences on the adoption and expression of alternative mate-acquisition behaviours. In this study, I tested two hypotheses. First, satellite males produce relatively unattractive advertisement signals and hence are at a competitive disadvantage when using the primary tactic. Second, satellite males associate with males producing the most attractive advertisement calls and hence increase the chance that they will intercept a female. Satellite males recorded in the field produced advertisement calls higher in frequency and shorter in duration than those produced by callers. Females consistently preferred the lower-frequency call alternative presented in two-speaker choice experiments, although they showed no preference in regard to call duration. In a second set of two-speaker choice experiments, noncalling males showed phonotactic behaviour similar to that of females, and their acoustic preferences roughly paralleled those of females. This phonotactic response may enable males producing unattractive calls to use the satellite mating tactic in a manner that maximizes potential reproductive fitness.