Apr 9, 2013 at 11:09 pm #1301516
@ryanLocale: Northern Rockies
Companion forum thread to:Apr 9, 2013 at 11:48 pm #1974752
@luffarjohanLocale: Wrong place at the right rime
Interestning but not surprising. After having seen trained dogs look for human tracks on pavement, humans in avalanches, munitions, truffle or whatever, it's easy to believe there's no limit.
One important thing to think about when avoiding "scent detection" is wind direction. May be hard to predict bear direction though…
I only have brief experience with hiding food in bags in the smokies one night a couple of years ago. Since where I usually roam there's no need for food-bags it was all new to me. Turned out ok but my measures where literally worthless if a bear would have been close.
But to the question! What's the brand and the weight of the see-through bandana the officer in the 4th picture has over his eyes?
I see multi-purpose use, sunglasses and cap. :)Apr 9, 2013 at 11:58 pm #1974754
Well done. I'm glad this experiment was completed, and from a layman, it is a little surprising. Thanks.Apr 10, 2013 at 12:06 am #1974756
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
Way to go!
Demonstrating marketing 1, science 0, for the claims.
Most excellent study.
CheersApr 10, 2013 at 12:09 am #1974758
Wow, this is really great, well done organising this.
I find the results unsurprising and a good reminder that there aren't any shortcuts to bear safety.Apr 10, 2013 at 12:13 am #1974759
The Animal Kingdom never ceases to amaze. I'd MUCH rather hear about this kind of thing in the news than the nonstop stupidity of our fellow humans.Apr 10, 2013 at 1:05 am #1974761
Amazing stuff. Many thanks for such a thoughtful and meticulous study.Apr 10, 2013 at 4:29 am #1974774
–Apr 10, 2013 at 5:15 am #1974778
Excellent Study – Much Thanks for publishing it.
Raises a lot of interesting questions in my mind … here are two:
I wonder about the rates of permeability … given how quickly the dogs found their targets it doesn't seem like doubling the bags would help.
I also wonder about vacuum sealer bags used for home dehydrated meals. (If odiferous smells can get permeate out, then can O2 permeate & get in? … same question about commercial freeze-dried offerings)
Ok, Art – when are you going to publish the next set of experiments? :-)Apr 10, 2013 at 5:34 am #1974779
excellent article! I am not surprised by the findings, although I still believe OP sacks likely reduce odor transmission better than a standard zip lock and still have some value when used in conjunction with a proper hang or inside of a bear canister.Apr 10, 2013 at 5:50 am #1974780
Great work. I have always been sceptical of the OP bags and have not purchased them. I assumed they were no better than ziplocks. But I am a little surprised though that neither seems to have much useful effect.Apr 10, 2013 at 7:08 am #1974799
@ikeLocale: Central Michigan
Thanks for the nice comments, guys. We had fun performing this study and the dogs thought it was a great game.
"I am a little surprised though that neither seems to have much useful effect."
@Ben– We only looked at whether the odor-proof bags performed better than ziplocs. We did not address the question of whether either had a useful effect at all. Here is an abstract suggesting that ziplocs may decrease bears ability to smell food, though one has to wonder whether the difference between 6 and 9 seconds is significant in a practical sense.
Wilderness & Environmental Medicine
Volume 21, Issue 4 , Pages 375-376, December 2010
Ziploc Bags for Preventing Bears from Smelling Food
Background.—Wilderness activities occasionally result in
bear-encounters. To deter bears from detecting food scents, the
American Bear Association recommends double-bagging food
carried into the wilderness.
Objective.—Our objective was to determine if food sealed
in double-bagged Ziploc bags would decrease the ability of
bears to detect food scents as compared to food in unsealed
Methods.—This was a prospective randomized singleblinded
study performed on bears at Northwest Trek Wildlife
Park, WA. Two black bears (Ursus americanus) and 2 brown
bears (Ursus arctos) were presented with open buckets in front
of their enclosures: one concealing food wrapped in 2 layers of
Ziploc bags and another with empty Ziploc bags. The time the
bears spent at each bucket was recorded for 30 seconds. In the
first phase, Ziplocs were open; in the second, Ziplocs were
Results.—The average time the bears spent at the open
Ziplocs with food and open Ziplocs without during the first
phase of the experiment was 9.573 and 6.613 seconds, respectively
(N _ 75). The average time spent at the closed Ziplocs
with food and closed Ziplocs without in the second phase of the
experiment was 6.25 and 6.8875 seconds, respectively (N _
80). The standard deviation for all average times was 1.5
seconds. An independent samples 2-tailed t-Test demonstrated
a statistically significant difference (P _ 0.032) when compar-ing
the time the bears spent at the open Ziplocs with food to the
closed Ziplocs with food. There was no statistically significant
difference between the controls from both phases of the experiment
(P _ 0.854).
Conclusions.—The bears spent a statistically significant
greater time at the open Ziplocs with food compared to the
closed Ziplocs with food. These data suggest that sealing food
in 2 layers of Ziploc bag may decrease the ability of bears to
detect the scent of food from within. We advise following the
Clark M. Rosenberry, MD
David C. Hile, MD
Troy H. Patience, BS
Fort Lewis, WA, USA
Richard L. Sartor, MS
Angela K. Gibson, MS
Northwest Trek Wildlife Park, WA, USA
@Tony– I can answer your question about foodsaver bags, though not with a direct comparison. I had relied on the police officers to provide the "scent packets" for the study. Naively, I only questioned type and weight of the product, but not how they were packaged. After the study, I theorized that the seal must be the weak link in these bags and proposed a second study where we would investigate bags that were heat sealed to remove the opening. The officers laughed and told me the dogs would find them anyway. As it turned out, the drugs we used were sealed in foodsaver bags and then wrapped in a heavy canvas outer covering to protect the dogs from accidental exposure. I don't pretend to understand the intricacies of olfaction, but I developed a tremendous amount of respect for the dogs over the course of this study. Scent will find a way.Apr 10, 2013 at 7:10 am #1974802
@wandering_bobLocale: Oregon, USA
I'll be curious to see what the manufacturer of OP Sacks has to say – if anything.
Is it safe to assume you provided them with a courtesy copy of your article?
Thanks for your time. Please keep us advised.Apr 10, 2013 at 7:22 am #1974804
@pgasbyLocale: North Carolina
I'll say it's things like this (and many others) that make BPL such a useful resource for a newbie like me – and by the responses for experienced backpackers as well!
This weekends trip with my sons Scout Troop is to Panthertown Valley, NC which is located within a NC designated black bear sanctuary and was subjec to a National Forest Service bear alert regarding some bears entering campgrounds and taking down bear bags.
I've been spending some time looking at bear safety myself, and our Troop has done a session on bear safety with the scouts. I have a bear canister I'll probably take along since I have it (UDAP No Fed Bear I got at STP for a good price with coupon) despite the weight. I'd been thinking about the odor sacks for my stuff as well given that the canister does nothing for odors and this article gives me pause to consider whether it is worth the effort.Apr 10, 2013 at 7:30 am #1974807
It is obvious that you will need a "Bag Handler" who has NO food/scent odors.
No foods in the pack.
Sitting 100 yards away during food prep and trailside lunches.
If this individual eats, s/he will have to be naked, and then take a bath.
I'm sure there are other considerations as well.
Best of Luck.Apr 10, 2013 at 8:07 am #1974820
Thanks for confirming this. I've already had many very experienced thru-hikers tell me OPSAKs are useless…good to know it's not just speculation.
I suspect you could've made a lot more money by forwarding this article to High Times Magazine instead of BPL. This info could potentially keep a lot of "entrepreneurs" out of trouble.Apr 10, 2013 at 8:11 am #1974823
@ikeLocale: Central Michigan
I asked the officers what would happen if the dogs couldn't find the bags. They told me that they would all buy stock in the company before the article got released.Apr 10, 2013 at 8:14 am #1974824
@cameronLocale: The WOODS
Did any of the officers mention people using vacuum sealed bags to fool dogs?
For lack of a better option I'm thinking I might vacuum seal individual meals and wash the outside of those meals very thoroughly. Obviously there will still be odor I'm just hoping it will be less odor then if I'd left a hunk of greasy summer sausage out.
For black bear I'm not too worried. Where I hike they are hunted and unlikely to bother me. Grizzly country would be the one place I'd go overboard with the whole vacuum sealing idea.Apr 10, 2013 at 8:22 am #1974827
Excellent work, Ari! I'm glad this research got published – it's just the kind of work that we need here on BPL!
I have a great deal of respect for dogs' scenting abilities, and seriously doubt that bears are any less able. Depending on "scent proof" bags is obviously not a viable technique for food safety in bear country.
Thanks again, and be sure to give your officers and dogs a big "Thank you!" from BPL!Apr 10, 2013 at 8:25 am #1974829
@jshannApr 10, 2013 at 8:51 am #1974843
@kylemeyerLocale: Portland, OR
One thing missing from this study is proximity. I certainly understand dogs (or any creature) identifying food when it's literally inches from it's nose, but I'm curious what the rate of detection would have been from 3 or even 6 feet away, emulating the distance a bear bag would be from the snout of a bear. Additionally, trapping odor in a locker with the ability to extract the air easily via a vent would seem to enhance the ability for a dog to detect the bags.
In open air, at 6 feet away, my guess is the results would be very different.
That said, thank you so much for doing this study. We need more of this on BPL.Apr 10, 2013 at 9:01 am #1974847
@pitsyLocale: Central Texas
Out there waiting for you, is a bear. He can smell what you're thinking. He can smell what the weather is going to do. He can smell your car's tire pressure. He can smell that your bike isn't shifting right. He can smell how Stonehenge was built. He can smell the origin of the Universe. He can smell everything.Apr 10, 2013 at 9:10 am #1974850
@courtenayennisLocale: Southwestern BC
It's great to know there is little practical difference in odourproofness between Opsak and Ziplok.
One observation from using both:
Odour permeability aside, the actual seals on Opsak bags are, in my experience, terrible. The bags can open in packs far more readily than Ziploc seals. Even if the odourproofness was perfect, it's a huge problem that the seals are so weak. I was putting everything in my Opsaks in Ziplocs, first, as a backup, but now I'll just forego the Opsaks altogether.
If Opsak could greatly improve their seal, I might still buy them, in spite of this study, for the additional piece of mind, but in lieu of this study, with their current seals… no point whatsoever.
Thanks for the great study! Love the care taken in designing it.Apr 10, 2013 at 9:28 am #1974856
This article has saved me money, because I don't see any reason to buy OP sacks again. Hard as it is to take for light and ultralight backpackers, it appears the the only sure way to prevent food from being destroyed by bears or other animals is to use a hard sided bear canister. Hats off to BPL for publishing this article, because you are going to get some flak from OP sack companies, I can guarantee you that.Apr 10, 2013 at 9:32 am #1974858
If a bear is a few feet from food in an odour proof bag I have no doubt that it will zero in pretty quickly.
To me the value of the odour proof bags are when the bear is a few hundred meters away, or some wind. The odour proof bags might possibly mute the smell enough to make it uninteresting in comparison to other natural (or unnatural sources), or possibly increase the difficulty in vectoring in on the source. If nothing else my opsak is coming along anyway to mask the smell of esbit, a task it does admirably.
I look forward to scorning odour proof bags becoming BPL dogma. I will add opsaks to my growing list of things I do or use but don't mention here any more, including but not limited to: trekking poles, hydration bladders, light hikers, white gas stoves, fleece, knife instead of scissors, bear spray, venturing out in the rain, drinking gatorade and using toilet paper.
(Edit: full disclosure, as a forum member, I did not read the article)
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