Simulating wood frog movement in central Minnesota, USA using a diffusion model

An important determinant of amphibian dispersal from vernal pools and colonization of other pools is the intervening land cover. We hypothesized that forest fragmentation alters the likelihood of amphibians reaching other pools. We used a correlated random walk diffusion approach to model wood frog (Rana sylvatica) movements. Our movement modeling was based upon 19,957 captures of wood frogs, including 397 movements among pools. Euclidean distance alone explained 46% (Poisson regressions, all p < 0.001) of the variation in movements, and a correlated random walk model without spatial data explained 62%. Using slope and a Landsat tasseled cap image of spring wetness, 77% of variation in movements was explained. Wood frog movements in Cloquet were modeled well without using surfaces that include forest openings. However, pool-scale analyses of movement have shown a relationship with forest fragmentation, and there is a secondary relationship between forest openings and spring wetness, which was used in modeling.