OTTAWA, Ill. (WCIA) — The oldest American bison at Buffalo Rock State Park in Ottawa has died, the Illinois Department of Natural Resources announced.

The bison, named Pebbles, died Tuesday afternoon at the age of 18. Officials said she was under veterinary care at the time and her death was attributed to natural causes.

The IDNR said there are two other bison who are still at the park: Cocoa and her three-year-old calf Hope.

The bison are not the only thing people at Buffalo Rock State Park can enjoy there, officials said. The park can also accommodate camping, hiking, picnicking, e-bike rentals and access to the I&M Canal State Trail.