Keep a look out for Bighorn Sheep. We found a few grazing near the side of the road, but most we saw were climbing over the rocky terrain. The ones with the larger horns are the rams (adult males), the smaller horns are the ewes (adult females).
Also, be careful where you put your feet and hands when scrambling over the rocks. Plenty of wildlife take cover in the shade.
Another visitor warned us about a rattlesnake he saw on one of the trails, though we didn’t see it. However, if you look carefully in the shade of the third picture below, you’ll spot a Chuckwalla lizard hiding from the sun.
For more information on wildlife in the area, check out the Valley of Fire State Park Wildlife Guide.