Choice of oviposition site by gray treefrogs: The role of potential parasitic infection

The role of potential infection by parasitic trematodes in the choice of ov iposition site choice by gray treefrogs, Hyla versicolor, was examined in a randomized experiment using 25 experimental pools. Treatment pools contain ing low (five snails) or high (10 snails) densities of either infected or u ninfected trematode vector Pseudosuccinea columella were compared with cont rol pools containing no P. columella. Treatments had significant effects on the number of gray treefrog eggs depo sited in pools. Compared to control pools, fewer eggs were laid in all trea tment pools, either because fewer pairs laid eggs, or fewer eggs were laid per visit. Pools containing infected P. columella also had fewer eggs depos ited relative to pools containing uninfected P. columella. The gray treefrog, H. versicolor, can discriminate between oviposition site s, based on the species present and the potential for infection. Choice of oviposition site can be a mechanism that determines the composition of ecol ogical communities as well as influencing parental reproductive success. Ou r results emphasize the importance of disease agents in shaping patterns of distribution, and they underscore the importance of understanding how pote ntial hosts may use behavior to mitigate infection risk.