Myself and 3 friends hiked into Merced Lake in Yosemite one year.  We went early to beat the crowds.  The ranger said the trail was not officially open but we could attempt it if we felt confident.  There were many downed trees still and much of the trail was flooded by melting snowpack.  We had the Lake to ourselves.  It was wonderful.  The first evening, we ate and bearbagged as we were taught back then (nowadays, I travel with a bear cannister).  We counter balanced our food bags 20 feet up out on thin branches.  During the night we were awakened by the sound of a bear cub making a small squealing sound.  We looked out our tents with flashlights and saw not one, not two, but three cubs in the tree.  BIG MAMA was at the base of the tree directing her cubs out on the limb.  Unbelievable.  We stayed very quiet so as not to agitate BIG MAMA.  And we watched a little cub get rope and bring it down to Mama who pulled down the food.  Would not have believed this unless I saw it.  We remained quiet because she had left the cubs at the tree.  Eventually she came back and gathered up her babies.  In the morning we followed the trail.  Torn food sack, half eaten can, yes can, of chili, ... we followed this trail up into the rocks where we found a graveyard of old stuff sacks, utinsils, and the obvious site of other campers lost food sacks.  The only thing not touched was a freeze dried corn package.  Luckily we had two sets of counter balanced food sacks and they had only taken the closest.  With a bit of fishing, we were fine.