Itâs time to praise pack rats. The small rodents with big eyes are helping scientists decipher climate change deep inside a chilly Wyoming cave. âPack rats compulsively gather all kinds of stuff in their nests â bones, shiny stuff, owl pellets, scat â and they bring it to their nest,â said Jenny McGuire, an assistant professor of Earth and Atmospheric Sciences at Georgia Tech University. At Natural Trap Cave in the foothills of the Bighorn Mountains, pack rats have built large nests on ledges above and around the 85-foot deep hole in the ground. Over the years, some of those objects have fallen to the bottom of the cave and been buried by sediment, leaving clues to the past.