Rivergal--This butterfly behavior is known as "puddling" and is quite commonplace along Park roads and trails where horses can travel. There's something about urine (probably salt) which attracts the butterflies. If you spend much time in the backcountry, especially along the trails where horses are allowed, you'll see lovely examples of puddling. Tiger swallowtails, in particular, seem to do this a lot.
Off hand, it's the sole thing I can think of positive to say about horses and Park trails. To me they are an abomination, and the damage they do to trails, especially in steep terrain, is enormous. It flies squarely in the face of sound environmental stewardship, but I don't think any Park superintendent has ever had the intestinal fortitude to address the issue. Certainly that's the feeling I've gotten in reading responses to letters written to various superintendents over the years. I get the feeling they aree with me but in typical bureaucratic fashion are afraid to stir the pot.
Along those general lines though, I will give the current superintendent credit for having taken a stance against allowing Cherokees to harvest ramps at will in the Park. There's a lawsuit on this matter at present, with the tribe putting clout and money behind it. They may well win, because native Americans have tended to win in similar situations elsewhere. However, if they can harvest ramps at will and in whatever quantity they desire, where will it stop? Ginseng might be next, or trout in unlimited quantities, but where it would really get interesting is with elk. After all, the tribal members could accurately claim, as they are doing with ramps, that killing elk is a part of their historic tradition. I guess I've stirred enough pots here so I'll shut my pie hole (or whatever the equivalent of that is when using a computer). Jim Casada