In wet years, juveniles once again disperse into underutilized sections of the preserve. At both study sites, long-distance dispersal of amphibians was documented during 1993. Because of unusually cool and wet weather, large numbers of larval amphibians reached metamorphosis even in usually ephemeral wetlands, and then remained surface active through the late summer and fall. Adult salamanders had been absent or rare in these areas previously. In some cases, such dispersal would have been difficult or impossible a few years earlier before intervening agricultural fields had been restored to prairie.
Habitat structure is also important.
In semi-permanent ponds without extensive emergent vegetation, larger predators such as Ambystoma tigrinum held other amphibian species to very low levels. In nearby densely vegetated ponds, the greater amount of cover allowed several species to maintain high numbers. Finally, surrounding terrestrial habitat influences the ability of adult amphibians to reach the wetland to breed. Species restricted to woodland are unlikely to breed in significant numbers in a wetland with no woody vegetation nearby. The role of the herbaceous layer is less well understood, but it may be of physiological importance to at least some amphibians.