Behavioral responses of a sex-role reversed pipefish to a gradient of perceived predation risk

Conspicuous behaviors such as courtship and mating often make animals susceptible to predation. When perceiving themselves at an elevated level of risk, animals frequently reduce conspicuous behaviors in trade-off for a decrease in probability of being preyed upon. In the present study, we used two experiments to examine the effect of perceived predation risk from cod (Gadus morhua) on nonreproductive and reproductive behaviors in the sex-role reversed pipefish (Syngnathus typhle). In the first experiment, no differences due to predation risk were detected in the nonreproductive behaviors of either males or females. In the second experiment, predation risk had significant effects on reproductive behaviors. Pipefish were allowed to court and copulate at four different predation levels. We created predation levels differing in perceived predation risk by controlling the number of sensory modes through which pipefish could detect the presence of a cod. As predation risk increased, pipefish copulated and courted less frequently, swam alone (displayed and searched for conspecifics) less often, and waited longer before commencing courtship. These changes in behavior minimized the amount of time spent above the eelgrass and presumably reduced conspicuousness to visual predators. Pipefish also copulated after a smaller amount of courtship as predation risk increased, indicating that they may trade information concerning mate quality for a reduction ill predation risk. No differences were found in any response variable between males and females. The role of operational sex ratios and intersexual competition in determining which sex assumes greater costs in mate acquisition is questioned.