According to the National Park Service:

"Pinnacles Overlook has sweeping views and faces South, making it a great sunset destination. This view displays the expanse of the Sage Creek Wilderness area. On clear days, the Black Hills are visible on the horizon. Bison might be visible in the distance, in the valley below or the upper prairie to the northwest. This overlook is also a popular spot for Bighorn sheep to gather. This is also a lambing area for Bighorn sheep in late April to early May, so it’s not unusual to see lambs traversing the rocky slopes of the Badlands."