Calling Site Choice by Hyla Chrysoscelis: Effect of Predators, Competitors, and Oviposition Sites

We examined the effect of predators, competitors, and conspecifics on the choice of calling sites by male gray treefrogs, Hyla chrysoscelis, and the correlations between choice of calling sites by males and choice of oviposition sites by females. The experiment was conducted in an array of wading pools and utilized a replicated block design for variance analysis. Pools were open to natural colonization by male and female treefrogs. The treatments consisted of controls containing no predators or competitors, four treatments containing one species of predator (either Ambystoma maculatum larvae, Enneacanthus chaetodon adults, Notophthalmus viridescens adults, or Tramea carolina larvae), and two treatments containing one species of competitor (either Rana catesbeiana or Hyla chrysoscelis). Male and female treefrogs avoided pools containing conspecific tadpoles and pools containing adult black—banded sunfish, Enneacanthus chaetodon. Females also avoided pools containing larval spotted salamanders, Ambystoma maculatum. Correspondence between calling sites and oviposition sites was examined in response to treatment, block (consisting of a location and a time), and location. Correspondence between male choices and female choices was weak. Number and location of calling males showed no significant correlation with the number and location of eggs along any of the axes of choice. Both males and females chose sites based on the species present, and both showed preferences in regard to location and time. The differences between male and female choices indicate that the potential choices have different values to each sex, or that different criteria are used to rank potential choices. Anuran reproductive behavior is not a simple consequence of the direct interactions between males and females, but is a result of complex interactions between the behavior of the two sexes and the environment in which their behavior is embedded.