The mounds offered good views of surrounding areas and may have served as territory markers, burial sites, or ceremonial places. Animal-shaped mounds were common, taking the shape of birds, bear, deer, bison, lynx, turtles, panthers, or water spirits. Bear and bird shapes prevailed along the Mississippi River in northeast Iowa and southwest Wisconsin. Today Effigy Mounds National Monument in Iowa protects more than 200 of these ancient Native American mounds, 31 of which are shaped as birds and bears. The Marching Bear Group, composed of 10 bear-shaped mounds, was first mapped in 1910 and is one of the key resources cited for creation of the national monument in 1949. You can learn more about the effort to document Native American monuments.