Conservation of young Southern leopard frogs should include forested habitats! [abstract]

Abstract

Throughout the world, amphibian populations have shown an overall declining trend. Frogs are a vital part of the ecosystem, and their absence could have many negative consequences. However, if we are to help conserve frogs, we must better understand their habitat requirements in all stages of life. Our experiments simulated forest and field habitats using soils, grasses, and leaves and allowed Southern Leopard Frog (Rana sphenocephala) metamorphs (very young frogs) to choose between the two. During each trial, frogs were put into individual aquariums divided into two halves. The following three experiments were conducted simultaneously: 1) forest soil plus intact litter vs. field soil plus intact litter; 2) forest soil plus crushed litter vs. field soil plus crushed litter; and 3) wet forest soil plus intact litter vs. dry forest soil plus intact litter. Frogs were left undisturbed overnight, and the next morning we recorded which side they were on. Thirty out of 33 frogs (91%) chose the forested side in Experiment 1. A lower number, 21 out of 33 frogs (64%), chose the forested side in Experiment 2. Twenty-one of 22 frogs (96%) chose the wet side of Experiment 3. Because frogs are dependent on moisture to survive, the results of Experiment 3 indicate that being in an artificial setting did not affect the frog's abilities to make a choice. Therefore, the high number of forest choices can be interpreted as a preference for forested habitats. Furthermore, the stronger selection for forest in Experiment 1 rather than in Experiment 2 may mean that the frogs are choosing habitats based on structure. For instance, dead leaves might provide much better cover from predators than matted grass. Overall, these results show that conservation and management practices concerning the Southern Leopard Frog should include the forested areas around their breeding sites.