Emergent Vegetation Coverage and Human Activities Influence Oviposition Microhabitat Selection by Invasive Bullfrogs (Lithobates catesbeianus) in Southwestern China

Abstract

Oviposition site selection is critical to increase offspring fitness for aquatic-breeding anurans, which generally lack posthatching parental care. Understanding factors that influence oviposition microhabitat choice would be helpful for managing and controlling invasive amphibians, such as the American Bullfrog (Lithobates catesbeianus), implicated in the decline of anuran populations across its invasive range. Factors that influence bullfrog oviposition microhabitat selection, however, remain mostly unknown. On the basis of field surveys from 2008 to 2013, we investigated 46 oviposition sites used by bullfrogs and 46 adjacent random unused sites and evaluated eight characteristics that could potentially influence oviposition site selection by bullfrogs in Caohai wetland, southwestern China, a global biodiversity conservation hot spot. We used model averaging of generalized linear mixed-effects models, using Akaike information criterion, hierarchical partitioning, and an ordination principal components analysis to analyze site selection. Results revealed that bullfrogs preferred waters with a high proportion of emergent plant coverage, whereas the distance to the nearest boat route decreased the probability of bullfrog oviposition site presence. Our study was one of the first quantitative studies on oviposition microhabitat selection by bullfrogs within their invaded ranges that combined abiotic, biotic, and human activities. We suggest that efforts to control and manage this global invader be directed toward reducing the suitability of breeding microhabitats by targeting areas with dense emergent vegetation, far from human disturbances.