Sixteen American bison were brought from the National Bison Range in Montana to an enclosed section of the refuge in March 2007 as part of the USFWS Pilot Bison Project. The number of bison reached 87 in 2013, forcing the USFWS to reduce the herd to just 60 animals as the limited acreage could not support so many animals. USFWS officials said that in a few years they will expand the bison acreage to , which will allow the herd to expand to an anticipated 210 animals.