Distributions of pond-breeding amphibians may be influenced by habitat factors at different spatial scales. We used anuran calling surveys to investigate the association between 5 anuran species and habitat variables measured within 100, 500, 1000, and 3000 m of sampling points at 63 coastal wetlands along the US shores of Lake Michigan and Lake Huron. Stepwise logistic regression was used to create predictive models for each species at each spatial scale. Our results confirm the view that habitat variables at multiple scales influence frog distributions, but the strength of predictive models was significantly affected by the spatial scale at which habitat variables were derived. Remotely sensed habitat variables within a 3000 m radius were among the most effective predictors of occurrence for American toad (Bufo americanus), eastern gray treefrog (Hyla versicolor), spring peeper (Pseudacris crucifer), and green frog (Rana clamitans melanota). The western chorus frog (Pseudacris triseriata) was predicted most effectively by variables derived within a 500 m radius. For the most part, these anurans exhibited species-specific responses to habitat variables; however the suite of landscape-scale variables associated with urban land use appeared in all species' regression models. Associations with landscape-scale variables coupled with well-documented habitat needs at local breeding sites suggest that conservation and assessment of frogs and toads in coastal wetlands should consider the influence of habitat variables at multiple spatial scales.
Bibliographical noteFunding Information:
This research has been supported by grants from the US Environmental Protection Agency’s Science to Achieve Results (STAR) Estuarine and Great Lakes (EaGLe) program through funding to the Great Lakes Environmental Indicators (GLEI) Project, US EPA Agreement EPA/R-8286750 and from the Zoological Society of Milwaukee. The Cofrin Center for Biodiversity, University of Wisconsin – Green Bay (UWGB) and the Natural Resource Research Institute, University of Minnesota, Duluth also provided considerable financial, technical and logistical support. We thank the UWGB GLEI field crew for assisting in field-work. We gratefully acknowledge Peter Wolter and Michael Stiefvater for providing remote sensing and GIS advice and support. David Dolan provided statistical recommendations. We thank Curtis Flather, Gregory Davis, Michael E. Dorcas, Michael Draney, and two anonymous reviewers for their helpful and insightful comments on the manuscript. Although the research described in this article has been funded wholly or in part by the United States Environmental Protection Agency through cooperative agreement EPA/R-82867501 to the Great Lakes Environmental Indicators (GLEI) Project, it has not been subjected to the Agency’s required peer and policy review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.
- Habitat associations
- Lake Huron
- Lake Michigan
- Logistic regression
- Predictive models