A Bear’s Sense of Smell

If someone were to ask you, “how does a bear smell,” you could answer in two ways. Bears smell real bad – or so I’m told – or bears smell exceptionally well, as I discuss below.

Big Black Bear

Bears are thought to have the best sense of smell of any animal on earth. For example, the average dog’s sense of smell is 100 times better than a humans. A blood hound’s is 300 times better. A bear’s sense of smell is 7 times better than a blood hound’s or 2,100 times better than a human.

Bears acute sense of smell evolved in order to help them find food, mates, keep track of their cubs and avoid danger, particularly between competing individuals. Except for mother bears, bears are territorial animals that need to range widely to find enough food to sustain themselves. A bear’s sense of smell is so acute that they can detect animal carcases upwind and from a distance of 20 miles away. You should just assume that they can smell the food in your food bag too.

Bears have an incredible sense of smell because the area of their brain that manages the sense of smell, called the olefactory bulb, is at least 5 times larger than the same area in human brains even though a bear’s brain is one third the size.

Bears also have highly developed noses that contain hundred of tiny muscles and let them manipulate them with the same dexterity as people’s fingers. The surface area inside their 9 inch noses also has hundreds of times more surface area and receptors than a human’s.

So the next time you make camp in bear country, make sure you hang a bear bag or store your food in a bear-resistant bag or cannister at least 100 yards away from your shelter. You should also seriously consider lining your food bag with an OPSACK 100% odor-proof plastic bag. These plastic bags are 17,000 times more odor-proof than normal ziploc bags and can significantly reduce the chance of a human bear encounter.

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18 Responses to A Bear’s Sense of Smell

  1. Hot Springs Guy August 17, 2008 at 12:27 pm #

    Awesome post! I've been experiencing an unfounded fear of black bears in the northwest in my travels this year. People are terrified of the black bears, so much, that they make decisions that actually antagonize the situation. I'm hoping to put a post up about just that in the coming months. Keep up the great work!

    One of the reasons I like backpacking so much is that you typically don't encounter 'trash' bears or other animals in wilderness – these unfortunate creatures usually hangout at the popular campgrounds and easy/popular hikes.

  2. Earlylite August 17, 2008 at 2:36 pm #

    Researching this article was really interesting. I have yet to meet a black bear face-to-face, but knowing that they can smell way in advance makes me doubt that I ever will.

    • Eric genre May 12, 2014 at 4:30 pm #

      Never say never. Last Monday night in the campground in stay at. I was coming out of the bathroom and came across a 300 lb. bear he was less than 2 feet away from . We both ran in opposite directions. It was

  3. Caribou March 5, 2009 at 6:58 pm #

    If they use red pepper in bear-spray containers,

    then why not grind some fresh red pepper cyan in

    a prosser,or coffee grinder. Just set it to a fine setting then fill an empty seasoning container. Before you hoist the the Bear-Bag up

    into the air, shake some of this pepper in the

    bag,…and on the bag too ! Just becarefull not

    to be down wind or breath to heavy around the

    food bag,…wear protective eyeglass's too.

    If the Bears sence of smell is that keen,…it

    will know that it is something to avoid.

    If you hear somthing …sneezing at 2AM its probly a Racoon or some FisherCat ??

    • john June 8, 2014 at 10:45 pm #

      You are a danger to everyone else out there

  4. Earlylite March 6, 2009 at 3:16 am #

    Sounds like a great way to self-inflict pain. I prefer to just hang the bag out of reach.

  5. ChaiG March 11, 2009 at 1:31 pm #

    I have yet to see anyone effectively hang food out of reach of a bear. For this reason, hanging food in places such as Yosemite, is actually illegal. A bear proof container is really the only way to go in bear country.

    Secondly, I don't believe those "odor proof" bags really do anything. If a police drug dog can sniff drug residue from a now empty ziploc, placed in the trunk of a locked car, I'm wondering how effective these bags will be once you touch the outside of them with food on your hands?

  6. TinyHorse April 22, 2009 at 4:49 pm #

    Great post!

    As a side note, you might want to avoid trying to bear-proof any food containers with anything like the bear pepper sprays. Apparently the residue from those sprays have been known to actually attract bears, at least those with capsaicin as the active ingredient.

    I think it's more about the stinging sensation when sprayed than the pepper smell.

    If you love bears, or are interested in them, you all should check out Bear Attacks: Their Causes and Avoidance<img src="http://www.assoc-amazon.com/e/ir?t=ultrarevie-20&l=as2&o=1&a=158574557X&quot; width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> It's a great book with a lot of valuable information about grizzly bears and black bears.

    That last part wasn't meant to sound like an advertisement. hehe

    Safe travels.

  7. Big Hank June 6, 2009 at 2:54 pm #

    What a fascinating read! My family and I have been so lucky in all our years of camping never to have had a bad experience with bears. I'm thinking now we might take more precautions than we have in the past, though, because I'm writing our positive experiences off to luck after this read!

  8. DaniLou June 8, 2009 at 5:27 am #

    Funny that I noticed this post this morning–just this weekend I went on a short camping trip to a state park just outside of Minneapolis, where there were not "supposed" to be any bears. I was in a backpacker site and had my food in an OP Sack. I was planning on hanging it, mainly to practice for an upcoming solo hike in the northwoods. It was late when I got in to camp (and I was lazy) and I ended up just putting the OP Sack in my tent (around here I mainly worry about smaller critters getting into my food rather than bears).

    To make a long story short I was woken up on Saturday morning by some rather noisy shuffling through the brush next to my tent. I expected to peek out and see a few deer grazing nearby. I was shocked when I stuck my head out the fly and found a huge black bear about 10 feet from my tent (and a small bear cub!). It didn't see me, and didn't even take notice of my tent or come any nearer, it just shuffled on through after about 5 minutes. I have to assume it couldn't smell the rather "stinky" contents of my food bag in the OP Sack. Obviously I was lucky considering my laziness in not hanging my food! But I was also impressed with the OP Sack.

    I later spoke to the ranger and it appears that this year given our spring drought the bears have vastly increased their range for foraging and so have moved into the public areas of the park, but so far have not caused any problems for campers. I was pretty scared when I saw the bear, so I did a little more research into what to do in a future encounter (other than hide in my tent!). I found a very interesting site with research-based information: http://www.bear.org. It definitely cleared up a lot of misinformation I had about black bears, and thought it might be of interest to others related to this post. I especially liked the numerous videos of bear interactions and also what their "bluff" aggression looks like and means. I'll still probably be scared if I am lucky enough to see a bear again, but hopefully I'll appreciate it more!

    • Michael January 12, 2013 at 4:43 am #

      The bear could smell the food, but it likely didn’t bother BECAUSE it smelled and heard you looooong before you even woke up. A mother bear is always on the defense when she has cubs with her. She has to defend them from any possible threat, because there are SO many and they are 100% dependent on her. Investigating a small amount of food *they have amazing sense of smell, so she’d know vaguely how much of a meal she’d find by what she could smell* while a potential threat is guarding it in an object (tent) she can’t identify was probably more than she was comfortable with.

  9. Earlylite June 8, 2009 at 5:38 am #

    You were very lucky. The first thing I always do when I reach camp is to hang a bear bag. Doesn't matter how early or late I arrive. It gets my food out of the way during camp preparations and helps avoid trying to hang it in the dark. Plus I always use an OP sack as a liner.

  10. Rebekah Jones July 6, 2009 at 9:37 pm #

    Please share your sources with me. Where did you find the size of the bear's olfactory bulb? And how keen it's sense of smell is in comparison to our own? Thanks!

  11. Earlylite July 7, 2009 at 2:56 am #

    I wrote that post a long time ago and had to do some digging to get those facts. But I can't remember where I found the info you want. I think I had to read some academic papers to find it – believe it or not, I actually know a lot about brain anatomy. I found everything via google however, so you should be able to too.

  12. Rebekah Jones July 7, 2009 at 8:54 am #

    I didn't mean to imply that I didn't beleive you; you probably do know more about brain anatomy than I do. I've seen similar figures scattered accross the web, but I haven't been able to find the research to back it up, and I need that in order to use it myself. I was just hoping that you had kept your sources. Thanks anyway. And thanks for encouraging people to keep bears wild!

  13. Brian July 20, 2009 at 4:42 pm #

    The OpSack works. Our group witnessed a black bear walking right by a full OpSack while checking out our camp, obviously looking for food. He was interested in various human smells on tents, etc., but didn't notice the food bag lying right there on the ground.

  14. michael league September 4, 2014 at 1:00 pm #

    Regarding those scent proof Opsacks: I meticulously, carefully sealed an open can of cat food in a ziplock, washed my hands, put on nitrile gloves and sealed that in an Opsack. Then I hid it under one of several clean towels on the tile floor of our family room. Our year-old beagle entered the room, stood still wiggling her nose about 5 seconds, turned to the correct towel and began sniffing directly over the cat food. She had the prize in under 20 seconds. I passed this along to the manufacturer, but no reply.

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