Published May 26, 2013 at 500 × 375 in USGS Study Confirms U.S. Amphibian Populations Declining at Precipitous Rates USGS Scientist Conducting Amphibian Research. Erin Muths (ARMI scientist, USGS) sampling frogs at a field site on Mt. Evans, Colorado. Location: Mt. Evans, CO, USA. Image credit: Don Campbell, USGS (Visited 11 times, 1 visits today)