Here are some excerpts from a trip report of someone who was just in the Yosemite area (
http://forums.backpacker.com/thread.jspa?threadID=69066&tstart=25). I've highlighted the updates of the Bear Vault "problem":
On August 1, 2005, at our Yosemite Valley, California, backpacking campsite, other campers warned our group of five that a large bear had just come in and ate their peanut butter in a jar on their picnic table while they were seated at the other end of the table. The bold bear did not leave the table until it finished all the peanut butter. We locked up all our food in the provided steel bear lockers and went to sleep. At 4:00 a.m., G-Force heard a campsite bear locker being rattled as if someone was removing an item from inside. At 4:30 a.m., our steel bear locker was noisily jimmied open and the contents were tossed aside in quite a rude manner. Our party woke up, and discovered a large bear had opened the mechanism somehow, and was going through some of our food that was inside the locker but outside our bear canisters. Jerry quickly ran naked from his tent and yelled at the bear to scare it away as the Park Rangers suggested we treat these habituated bears. Instead of running, the marauding bear turned on Jerry, took 3 or 4 steps in his direction, swiped its paw horizontally in the air at Jerry, and gave a deep loud grunt. Jerry retreated back to his tent, and the bear turned back to eating our food. By this time, I had gotten my glasses on, headlamp on, bear spray our, and took off the bear spray safety clip. The bear was busily munching away on four brownies from the restaurant buffet table, and a bag of cashews, while I snuck up 15 feet directly behind the bear. I looked behind me to see if there was running room if the bear spray didn’t work, and pointed and depressed the mechanism spraying towards the bear for one second as the bear spray label suggested. The bear spray mist surrounded the bear, and the bear stayed in the cloud for one to two seconds while I started backing away. In the furthest away tent, G-Force was watching and chuckling at this whole scene, and then the bear bolted straight ahead like it had just been kicked into the butt. G-Force saw another nearby bear that I had not noticed quickly follow the sprayed bear.
I waited 15 to 20 seconds for the mist to dissipate, and then went to return the items to the steel bear locker. Unfortunately, the spray had not completely dissipated, and I inhaled a residual amount of the spray, which sent me backwards choking in pain. Bear spray is nasty stuff, and I felt sorry for the bear at that point. Several minutes later, while holding my breath, I was able to return the scattered remains to the bear locker by holding my breath. My food was completely intact in my sealed Bearakaide Bear Canister, but my canister now had bear claw scratches etched in the outside where the bear had tossed it aside to get at food behind the canister. Later that day I made a complete report to the first Park Ranger we met as the Park requires. One Park Ranger we recounted this tale to down the John Muir Trail said in 17 years of working, he had never heard of anyone spraying a bear.
We spent 20 minutes discussing this incident and a bear problem at Charlotte Lake with Ranger George on day 19.
The Ranger was warning us of a problem bear that was opening the bearvault canisters by depressing the top until it deformed and popped off. I asked this Ranger if this bear came around our canisters (one was a bearvault), should I spray this bear too, and the Ranger said "yes".
Apparently some bears have swatted a canister over a cliff, and ate the contents after the canister shattered. Our bearikades recommended placing the canister in a depression or is some brush. From our experiences, we would place them downwind among some rocks with a pot on top to make noise if the bears tried to open them.
Ranger George said there were 24 reports of bearvaults failing, and 1 report of a bearikade failing. He was expecting a bear technician to arrive with three types of canisters, and the park bear technician was going to test them to see if the bear really could get into some of these designs. The results of that test is unknown to me.
There have been many reports of bears just walking past the bear canisters since they have learned that tying to get into them was a waste of time. But it only takes one success to ruin that.
Ranger George told us that one bear found a bear vault that was not completely closed, and was able to open it. The next night, the same bear found another bearvault, and this bear spent 4 or 5 hours trying to open it.
