This is a wild area, do not feed or approach the animals. The ecosystem here is fragile and easily damaged so please stay on the trails. The trails are very primitive and steep in spots and footing can be difficult. In addition, as with many steeper trails, there are these rocks placed across the trail to help channel rain runoff and decrease erosion.
Going to the top of Wheeler Peak demands attention to the equipment you bring up. The day may start out hot below at the roadend, but up high, it will cool quickly, especially if there is any wind. Take plenty of water with you, as well, and try to remain hydrated. Sometimes, aspirin, taken prophylactically, will keep headaches from the altitude at bay.