One part of the Grand Canyon experience that's not in the guides is that ravens are the official camp scavengers.  Cielo is the only toddler we know who can imitate a raven's call.  A bunch of frat boys drove up one evening, piled out of their SUV, cooked some burgers, ate them, then piled back in and drove off, leaving a feast for the opportunistic birds.  We managed to keep them away until our bedtime, but then we had to retreat so Cielo could dance on our heads for a few hours before she fell asleep.