Shortly after beginning their journey down the Missouri River in April of 1805 after spending the winter at Fort Mandan, Meriwether Lewis wrote in his journal about an animal that Captain Clark had recently observed: “Captain Clark walked on shore today and informed on his return, that passing through the prairie he had seen an animal that precisely resembled the burrowing squirrel, accept in point of size, it being only about one third as large as the squirrel, and that it also burrows.”