Wetland edge trampled by American Bison (Bos bison) used as basking site for Painted Turtles (Chrysemys picta)

Prairies of the Great Plains once were influenced by large-scale disturbances, such as fire and herbivory by large ungulates, that promoted ecosystem functioning. American Bison (Bos bison) created many types of disturbances as they traversed grassland landscapes. Trampling, a common type of bison disturbance, occurred when large herds moved through an area denuding aboveground vegetation, exposing prairie soils, and restarting succession. Bison reintroductions now allow researchers to use contemporary observations to examine influences of these large, hoofed mammals on system functions. Herein, we report on the immediate benefit of trampling along a wetland edge for another vertebrate species. We observed Painted Turtles (Chrysemys picta) basking in an area recently trampled by bison along a lake margin in the Sandhill Region of Nebraska. Basking generally is a thermoregulatory behavior for many species of pond turtles that optimizes physiological processes for individuals. Painted Turtles seldom leave the water except to nest, although they frequently bask on structures emerging from the water’s surface or along the edge of shorelines, such as logs, Common Muskrat (Ondatra zibethicus) houses and platforms, and vegetational mats. A paucity of basking sites at this lake, along with dark, exposed soils near the water, likely facilitated this on-shore basking event on a mostly sunny, but cooler day. Reintroduction of American Bison to grasslands helps reestablish former interactions between biota and allows land managers and researchers to better understand how bison management in fenced ranches affects local fauna.