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Bears and canisters

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Bears and canisters

Postby gregw822 » Tue Jul 07, 2009 4:12 pm

The post about the trip into Miter Basin evolved into a short discussion on bears and the use of canisters. I have a hard time fitting more than about 6 days worth of stuff in my Bear Vault. Some of it always ends up in my pack.

I have often wondered about freeze dried food. If a bear can smell it, that means molecules responsible for the scent have diffused from the package. This seems unlikely to me. If gas molecules can pass one way through the package, then they can pass the other way, too. That means oxygen would be able to diffuse into the package and result in spoilage. That doesn't happen. Moreover, the packages are vacuum sealed, and the vacuum would be lost if molecules could diffuse into the package, and that doesn't happen either. I don't think we have technology for single-direction passage of gas molecules. The same argument can be applied to any canned goods we happen to carry.

If I'm on a long trip and the canister won't hold all my stuff, it's the freeze dried that goes into the pack. I use odor-proof sacks (http://www.loksak.com/products/opsak), but I'm not sure they're necessary. I still use them, just in case.

I've never had a hint of bear trouble, but maybe I just lead a charmed life. So far. I do avoid wilderness campgrounds like Vidette Meadows. They have bear boxes for a reason. Good places to avoid.



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Re: Bears and canisters

Postby rlown » Tue Jul 07, 2009 4:23 pm

i'm thinking bears know what's in a canister, regardless of smell.
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Re: Bears and canisters

Postby gregw822 » Tue Jul 07, 2009 4:52 pm

The canisters certainly are not odor proof. I put my canister well outside of my camp area and put the extra freeze dried well away from camp on the far side from the canister. So far so good.

I have heard stories of bears chewing on canned goods. I think that happens when a bear is attracted to human smell and then spots by sight the easily recognized shapes of cans.
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Re: Bears and canisters

Postby Mike M. » Tue Jul 07, 2009 6:04 pm

I hang any food that won't fit in a canister. Obviously, above treeline, this is not possible -- but bears are rarely found up high, where they have no natural food source. The great majority of bear incidents occur in heavily trafficked areas well below timberline, where bears are wise to human food and come to look for it. There are rare areas in the Sierras where heavy human use has attracted bears to forage for human food above timberline -- Purple Lake is one place that comes to mind. If you have overflow food and you want to camp in such an area, you are risking a bear incident. Best to move on to a a treed area where you can safely hang your overflow food.

In an area like Vidette Meadow, which sees a great deal of bear activity due to heavy human use, I think it is best to store canisters at night in the metal storage lockers that are found there. Bears are tenacious beasts and once they focus on the canister in your camp, they will be a nuisance there all night and you won't get much sleep. I wish Park policy would encourage the removal of these outlaw yogis, but a different view seems to prevail at this moment in time.

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Re: Bears and canisters

Postby Mike M. » Tue Jul 07, 2009 8:30 pm

Correction -- Duck Lake, not Purple Lake.

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Re: Bears and canisters

Postby paul » Tue Jul 07, 2009 9:16 pm

A bear does not necessarily have to smell any of your food to get interested. The habituated bears are familiar with the smell of humans, and have learned that humans have food with them. But f you camp away from the usual areas, you are also camping away from the habituated bears, so you're less likely to have bear troubles. Of course, if you're frying fish....
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Re: Bears and canisters

Postby cvr » Wed Jul 08, 2009 10:54 am

Habituated bears have figured out that humans equal food availability, with or without food scent. One AM just outside of Little Yosemite Valley, a person in our group had a bear silently sneak up behind her while she was packing her pack to steal a freeze dried meal sitting on the ground no more than 1 foot from where she was standing. Neither she, nor anyone else, heard it coming. It must have been watching us and waiting for the right time to move in. I suspect it previously had numerous successful attempts at gaining human food and simply had learned that humans have food with them. Granted, Little Yosemite Valley probably ranks at the highest level of human use areas in the entire Sierra, but none of us could believe how bold this particular bear was.
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Re: Bears and canisters

Postby Grzldvt » Mon Jul 13, 2009 4:25 pm

Had the same issue, long trip(Twin Lakes/Matterhorn and back), not enough space in the canister and had to leave some food out. We thought we would be very clever and buried a freeze dried meal, and a couple of tuna cans down in some pretty deep and very narrow cracks in some rocks, pretty far off the beaten path. We could barely reach the stuff laying down and shoving our shoulder into the crack, and figured we were safe. Not so... in the morning when we went to get it, everything was pulled out, the tuna cans had holes punctured in them, and the freeze dried bag was mangled and slobbered all over.
Our canisters were stacked three high and were untouched. No clue how a bear even found the stuff, let alone got it out.
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Re: Bears and canisters

Postby fedak » Mon Jul 13, 2009 5:19 pm

Bears can smell the food through most retail packaging.

Odorproof bags help (they sell them at REI)

You're supposed to use the bags inside the cannister as well as the cannisters are not odorproof.
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Re: Bears and canisters

Postby oldranger » Mon Jul 13, 2009 6:22 pm

:soapbox: My experience has been that other than a bear box or bear proof container nothing will prevent a habituated bear from getting your food unless you are willing to vigorously defend your food and chase said bear at least 200 yards away from your food stash. When I used to horse camp I kept my food (and horses supplementary grain) in semi bear resistant boxes then piled pots and pans on top of the boxes. Even in a place like Vidette Meadows one long chase by a ranger in long underwear and cowboy boots screaming like a banshee and running after the bear for about 200 yards was enough to convince said bear that there must be easier pickens (and the next day I found out there were). I'm about as skilled at counter balancing food bags as you can get but I always try to attach something to make noise so a bear working on my stash will wake me up (consequently I keep my food, whether in a container or hung near my sleeping quarters (not over or right next to it) so I can respond with all the fury my 5'7" and 160 lbs can muster. Every year someone new comes up with Ideas like burying or sinking waterproof containers in a lake. Damn bears somehow manage to find the stuff. My worst experience came after a hard day when I went to retrieve a can of beer I stashed in a creek. You guessed it, I found a dented empty can with some nice puncture holes in the can! On the other hand before my rangering days I once watched a bear walk right past some food that I had forgotten to put away before I went to bed--go figure! Does that say something about the quality of my food? The bottom line is that bears are smart and if you think you have a fool proof way of keeping food from bears that no one has thought of before it is probably because it was tried and failed. And if it does seem to work maybe a bear just didn't pass by.

Finally if you choose to carry more food than you can bear proof then it is your responsibility to protect the food from the bears not the NPS to remove the bear.

Some thoughts from an old fart!

Mike
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Re: Bears and canisters

Postby Mike M. » Mon Jul 13, 2009 6:45 pm

Mike (Old Ranger):

I agree with everything you have written, EXCEPT the last thought about the NPS's responsibility for removing problem yogis. When a bear lashes out at a human, as one did to that poor older guy in Vidette Meadows, it's time to ship the bear out or put him down. That older guy was trying to protect the food in his canister, and while he was certainly imprudent in moving so close to the problem bear that the bear could take a swipe at him, the bear crossed a fateful line.

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Re: Bears and canisters

Postby jenmtn » Tue Jul 14, 2009 1:36 pm

I can't think of any legitimate excuse for not storing food properly in the Sierra other than laziness to carry an extra canister. The point of a bear canister is not to conceal odor. Making food "odorless" does not change the fact that it is human food. Sierra bears are smart, sneaky and KNOW that many wilderness users often (as is especially apparent in this discussion) are not vigilant about storing food properly. It is OUR responsibility as wilderness users to protect bears from the addicitive nature of access human food and quick calories.
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