GRASSLANDS The Monument contains specific resources for which it was declared a National Monument. Special resources (called "objects" in the Declaration) include archeological features such as ruins and petroglyphs, and natural features such as the green riparian zone and associated wildlife along the Agua Fria River. Natural features also include spacious grasslands that provide habitat and a migratory corridor for the American pronghorn, the fastest mammal in North America. Nesting and migratory birds rely on the grasslands for providing seeds and insects for nourishment. Native peoples have inhabited and used the grasslands for perhaps thousands of years. This March 2013 photo shows the grassland with a vegetation plot . The FAFNM Natural Resources Committee conducts field trips to monitor this plot that excludes cattle.