Bison range freely throughout the park so you might encounter them on any of the trails. Keep at least 50 yards from them to avoid being charged (by the bison or the park police).
This trail starts at the parking area for the Canyon Loop Trail. Most of the trail is an easy singletrack that runs right next to the main park road.
At the end, you'll plunge down into the wash for the South Prong of the Little Red River. The descent is steep and rocky with a side of ruts and loose surface. The steep climb out on the other side of the wash features loose surface with ruts and a side of rocks. To add to the fun, this was the only "wet" crossing in the park that had any water in it when I was there.
At the top of the climb, you can turn right to take a short path (another tricky descent) out to the main road or left to the Lower Canyon Trail.