Fig. 1.

Hierarchical study design. All data used in our study followed a common design. Study areas were located across the United States and Canada (a). Individual sites were sampled within each study area, where a site was defined as a waterbody, terrestrial plot, or reach of a stream (b). Sites were visited multiple times each year and for multiple years. During each visit one or more species were recorded as detected or not (c). Overall we sampled from 86 unique study areas and data included observations for 81 different amphibian species. Maps used in this figure were generated using R package maps