As human impacts increase in national parks and the greater ecosystems surrounding them, the National Park Service faces the difficulty of monitoring ecosystem changes and responses of key wildlife indicator species within parks. Responses of bison to trail grooming in Yellowstone National Park (Wyoming, Montana, and Idaho) and control of the animals once they leave the park (Bruggeman et al. 2007), migration of wildlife across park boundaries (Griffith et al. 2002; Berger 2004), effects of restored wolves on vegetation communities through trophic cascades (Hebblewhite et al. 2005), and responses of wildlife to the use of prescribed fires all represent problems in understanding how the greater park ecosystem and wildlife populations change over time (Fagre et al. 2003). When you also consider ecosystem responses to climate change, the tasks facing national park scientists in the 21st century seem daunting.