For the first time since the 1840s, purebred baby bison were born on a Missouri prairie. The Nature Conservancyâ??s Dunn Ranch Prairie, located in the northwest corner of the state, welcomed eight bison calves this spring â?? three of which were born on Motherâ??s Day.Thirty-six bison were released in October of 2011. The herd roams native tall-grass prairie within a 1,200-acre fenced enclosure. Ultimately, a second 1,250-acre unit will be added to increase the herdâ??s roaming area.The bison were reintroduced not only to restore a piece of Missouri's natural heritage, but also to restore the grassland ecosystem. Bison graze differently than cattle. Their eating habits and other behaviors increase the number of native plant and animal species on the prairie. Native birds, for example, require diverse plant structure on the prairie.Randy Arndt, Grand River Grasslands site manager, says, â??Grassland birds need a wide range and diversity of habitat types. Some of them prefer short grass, some of them prefer long grass. Some birds need last yearâ??s vegetation to nest in, some need this yearâ??s vegetation.â??Bison are used with prescribed fires to manage the prairie. Dunn Ranch staff burn different portions of the prairie seasonally. The freshly burned areas produce lush, green vegetation that attracts bison, creating shorter grass habitats. Bison avoid areas that have not been recently burned, allowing grasses in these sections to grow taller.The Conservancy has worked to restore the 4,183-acre Dunn Ranch Prairie in Harrison County for over a decade. Native reseeding, tree removal, invasive species control and prescribed fires have produced dramatic results on the prairie.Today the site boasts more than 300 native plant species, thriving populations of native birds, and now â?? after more than 160 years - the iconic American Bison.There are more than 400,000 bison in public and private herds in the United States, but the herd at Dunn Ranch Prairie is unusual because it is one of only eight herds in the country that have not been crossbred with cattle (based on standard genetic testing).The Conservancy has more than 25 years of experience in bison management. All bison are routinely vaccinated and tested for disease. The Nature Conservancy is a private, nonprofit organization. The bison reintroduction is funded through foundations and individual contributions.