On my way down from Muir, almost at the bottom of the switchbacks, a park ranger actually asked me for my permit. I told him I had it in my hand looking at the permit when a Stellar Jay flew by and grabbed it with it's peak. Then the Jay rolled it up and smoked it in front of me on a branch, while calling me names. Needles to say, the ranger didn't believe me. I had to pull it out and show it, along with the WAG bag. So beware, they do check the permits occasionally.