Invasive species are a major focus within conservation biology. The widely introduced Cane Toad, Rhinella marina, has attracted particular interest in studies of the effects of invasive species on native communities. In this study, we examined the effects of competition with invasive Cane Toad larvae on the growth, development, and survival of native White-lipped Frog (Leptodactylus albilabris) larvae. We conducted two experiments; the first was a food calibration experiment to determine appropriate high and low food concentrations, and the second was a competition experiment in which we varied species compositions and food availability. In the food calibration experiment, lower food levels reduced the survival of both species. In the competition experiment, the presence of R. marina reduced the proportion of L. albilabris that survived to metamorphosis under the high food treatment. Otherwise, the introduced species had little negative impact on the native species. In contrast, larvae of R. marina experienced severe reductions in growth and survival in the presence of L. albilabris. Significant effects of the presence of L. albilabris on R. marina development were observed as early as the first two weeks, and continued up to metamorphosis. We conclude that L. albilabris larvae outcompete R. marina larvae when their numbers are approximately equal. Adaptations to life in ephemeral habitats may have provided L. albilabris with a competitive advantage over R. marina. Further studies are needed to determine if these patterns persist under natural conditions.
