The Mississippi and Yellow Rivers and adjacent wetlands form the preferred habitat of many small mammals. Chipmunks, squirrels, beaver, muskrat, river otter and mink occupy the quiet sloughs and river edges. Floodplain and upland forest provide food and habitat for larger mammals such as the whitetail deer, gray and red fox, and the coyote.
Up until the mid-1800's northeast Iowa supported a small elk population. Following European settlement, the elk disappeared from the region. Likewise, the timber wolf populations disappeared by the 1930's. In recent years, evidence of bobcats has been found in the Yellow River valley. Isolated reports of wolves, black bear and mountain lions have increased steadily over the past ten years. Although it is suspected these reports constitute the adolescent wanderings of young males, the rugged terrain in the area may provide the right combination of habitat and seclusion to encourage these species to once again make the Effigy Mounds region their home.
