The snake you don't see is usually the one that bites you. Despite frequent visits over the last 25 years, I've never seen a rattlesnake at The Rock. The greatest danger to hikers anywhere in Texas is dehydration and heat stroke. Distances in nature are deceptive. What appears to be a short stroll often turns out to be an ordeal, especially to hikers who start out with little more than a soft drink or been in their hands.
Alcohol actually accelerates dehydration.
And soft drinks are wet but not thirst quenching. For a day hike in the summer, a half gallon of water per hiker is recommended. Or, assume a water intake of one gallon every tem miles for extended hikes. Symptoms of dehydration include dizziness, slow motion, nausea, drowsiness, loss of appetite, dry mouth, difficulty in breathing, the inability to walk, and finally, fainting. Drink water, even if you're not thirsty, because thirst, or the lack of it, is no indication of dehydration.