Wednesday, August 8, 2007 - 3:40 PMCOS 83-7: Breeding site selection and tadpole performance of the gray treefrog (Hyla versicolor) in response to a forest gradient
Daniel J. Hocking and Raymond D. Semlitsch. University of Missouri
The harvesting of forests often leads to a decrease in amphibian diversity and abundance. However, the ecological mechanisms generating these patterns are poorly understood. We performed experimental forest manipulations around amphibian breeding ponds as part of the Land-use Effects on Amphibian Populations (LEAP) project. In a previous study, we found that gray treefrogs (Hyla versicolor) prefer to breed in clearcuts compared with thinned and control forests. Here we examine breeding site selection and tadpole performance along a forest gradient from interior forest to forest edge, clearcut edge, and clearcut. At three replicate sites we allowed H. versicolor to oviposit in cattle tanks. There was greater oviposition in the tanks in the clearcut edge than in the clearcut, forest edge or forest treatments. We then tested the influence of breeding site selection on tadpole performance. One hundred tadpoles were added to tanks at the same locations as the oviposition tanks. We found that time to metamorphosis was shorter and survival was greater in the two clearcut treatments than in the forested treatments. Our experiments reveal that breeding in open canopy ponds can have fitness advantages over forested ponds for H. versicolor. Our results coupled with life history information suggest that H. versicolor may have evolved to exploit small scale disturbances such as blowdowns where new ponds are created under open canopy. As forests mature around restored wetlands, managers should consider maintaining some early successional wetland habitat for species such as the gray treefrog and for maximizing biological diversity.