we were in yellowstone in july,, wolves in lamar valley, a long distance away though. Bears between mammoth and canyon by way of tower, Have never seen porkies in yellowstone, would ask a ranger there. Good luck and have fun, DAve

Thanks Dave!

The porcupines should be in their mating season and more active during this time frame. My experience has been that they are more prevalent in area with lots of evergreens.