Mule deer fawns are typically born mid June and July in Yosemite. People concerned about these young animals often pick them up or pet them, which will likely reduce their ability to survive.
Fawns are born relatively scentless and are brown with white spots. These characteristics provide camouflage which allows fawns to conceal themselves from predators: this is their primary form of defense. When approached by a human, the natural response of a fawn is to remain still and silent, lay its head down and try to hide. Even when physically touched, the fawn may not move. Adult female deer do not remain close to their fawns in order to prevent drawing attention to them. The adult female deer will come to find them several times per day to nurse.
The best course of action when you see a fawn is to leave it alone and keep your distance from it so that the adult female can regularly return to nurse.