close up of bison stack excrement. a non-invasive method used for studying threatened species.

animal biological biology bison characteristics close closeup corpolites crap data defecate description digested dirty droppings ecological ecology education environment excrement fauna feces fibrous globular idetification life mammals method monitoring morphometric national natural nature noninvasive observation outdoors park pie poop rocks scat science scientists shit species stack stones studying terrestrial threatened tracking usa used wilderness wildlife wyoming yellowstone