Insects
Critter Perspective
While bears are big animals, and can be dangerous under some circumstances, most hikers never have a problem. The only other large predator in the Sierras is the mountain lion. While there have been a few lion attacks in California in recent years, these animals are generally very reclusive and avoid human contact. You are much more likely to have problems with rodents (we sure did). There are definitely dangers in the Sierras, but big animals are not high on the list. Careless accidents, falls, burns, physical sickness, and other similar mishaps are much more likely to cause problems.
Insects can be particularly vexing, especially mosquitoes. During the hatch, they can make your life miserable. Unfortunately, the peak activity period varies depending upon elevation, and seasonal conditions. An area that was mosquito-free two weeks ago can be a buzzing hell—and visa-versa. It’s hard to tell. We planned our trip in late August for two main reasons: mosquitoes would likely be less of a problem, and streams would be lower and be easier to ford. We carried
DEET, but rarely needed it. In camp our tarp-tents had mosquito-proof netting, but we never needed this. In fact, many nights, we slept in the open with no insect problems. There are other insects, particularly ants that are active throughout the summer. Don't camp where you see them active, and you should be fine. A few ants may crawl over you, but hey, they're thru-hikers, just like you!
Snakes
Snakes, including rattlesnakes, are simply not a problem at the higher elevations of the John Muir Trail. Above 8000' rattlers are rarely encountered, and most of the JMT is above that elevation. Rattlesnakes are more common in the Sierra foothills, but they may be seen in Yosemite Valley and on the climb up to Tuolumne Meadows. Watch where you put your hands and feet on the climb out of the Valley, and you shouldn't have a problem.
Other Obstacles
After spending time in the back-country, the somewhat irrational fear of being isolated far from civilization becomes significantly less. There are constantly things that must be dealt with, but with a little planning and experience, most physical obstacles can be handled safely. However, psychological obstacles can be even more formidable than physical ones. Most thru-hikers seem to struggle with inner struggles of one sort or another. When things do not go according to plan, or physical hardships seem overpowering, we might question our ability, commitment or our partners. The nice thing about the JMT, though, its manageability! It's not really long, like the PCT or the AT, consistently bad weather is not usually an issue, and in a real emergency, there are plenty of people on the trail, so help is available.
Before the hike, I had a number of anxieties. Would my knees hold up? Could I handle the high passes? Would there be snow or ice on them? If there was, would my trail shoes be adequate? Would my partnership with Craig become uneasy? Would our schedule prove realistic? Would my equipment be adequate? And on and on... Once on the trail, my perspective quickly changed. I still worried a bit about my knees, but other things seemed less important. Would there be ice on the passes? Well we'd find out when we got there (it turned out they were clear). Would my shoes, rain gear, backpack etc. work as expected? Well, I had little choice, but to do the best with what I had—though I did take some notes about what I'd change next time.
Trail Routines