Cold spray works

A healthy grizzly bear on the prowl/Wikimedia Commons

As the snow creeps down the mountains of coastal Alaska and the temperatures drop, researchers from the Lower 48 have good news for bear wary, end-of-season hikers:

Bear spray has now been shown to work in the cold.

“Even at the lowest temperature tested (-23 degrees C), bear spray had a  range greater than four meters (12 feet), though the plume was narrow and spray was not well aerosolized,” they report in The Journal of Wildlife Management this month.

Minus 23 degrees Celsius – about 10 degrees below zero to Alaskans more familiar with the Fahrenheit scale – is a temperature that normally equates with  bears having disappeared into hibernation, and most hikers having transitioned to skis, snowshoes, snowmachines or fat biking.

Most Alaskans engaged in those activities don’t worry much about bears, but some might still be thinking about carrying bear spray – a pepper-based irritant that will drive off most mammals – to deal with aggressive moose.

Old unknown

How well spray works in the cold has been the subject of considerable discussion for years among outdoor-oriented Alaskans.

Biologist Tom Smith, the lead author on the study, is a former Alaskan. He studied bears for the U.S. Geological Survey and the National Park Service in the state for 14 years before becoming a professor at BYU. 

In the abstract of the new study, he along with scientists from the U.S. Fish and Wildlife Service, Polar Bears International, the Ontario (Canada) Ministry of Natural Resources, and the University of Utah make note of bear-spray failures that “have been reported along with speculation regarding the influences of temperature, wind, repeated canister use, and canister age….’

Some of the spray failures are due to age, a problem addressed in the study. Others have been linked to manufacturing errors. UDAP, maker of a popular bear spray sold at the Costco wholesale stories in Anchorage, was this summer warning of bear-spray canisters lacking pressure.

The company recommended purchasers test fire their UDAP cans before using them. It is not the only company to make this recommendation.

“Both manufacturers (UDAP and Counter Assault) of the products we tested recommend test spraying prior to initial use to verify pressurized contents and also recommend cleaning the nozzle assembly with soap and water,” the study said.


The researchers did not think test firing a good idea, but offered no concrete advice on how to otherwise test cans.

“Our findings show that testing bear spray, even with short bursts, rapidly depletes head pressure, reduces the amount available, and leaves noxious residues on the nozzle, which ultimately find their way onto hands, face and clothing,” they wrote. “Therefore we recommend not testing cans and carrying fully charged, unexpired product when in bear country.”

The study hints that maintaining records on the weight of cans could indicate whether propellant is leaking, thus rendering them less efficient. But this would appear contingent on having a base weight for a can known to be fully charged and operational.

When the researchers weighed 34 unused cans of Counter Assault, some up to 18 years old, they reported finding “no relations between canister weight and head pressure, which seemed surprising given the moderate correlation between canister age and weight.”

The amount of spray in even a fully charged can is notably limited.

“Once triggered,” the study says, a can of bear spray loses half its head pressure in the first 1.4 seconds and completely exhausts in seven seconds. The loss of pressure and hence spray plume distance is rapid from the onset and nearly exhausted only four seconds into continually spraying the can.”

Once the can is empty it is useless, unlike a firearm which can be reloaded if the person carrying it has brought extra ammunition. The study does not get into the merits of spray versus firearms for bear protection, but the authors admit to a bias in favor of spray.

Save a bear

“We can contribute to bear conservation by reducing bear mortalities due to human-bear conflicts,” they write. “Bear spray is an effective, non-lethal deterrent when dealing with brown, black and polar bears.”

Brown/grizzly bears are a threatened or endangered species in most of the Lower 48, and the same is generally true of polar bears throughout their range. Brown/grizzly bear populations in Alaska are, however, healthy, and there is a biological argument to be made that removing from the gene pools bears which lack an inherent fear of people contributes to the conservation of both people and bears.

The authors do concede that “persons proficient in the use of firearms, as compared to those who are not, have a decided advantage in an aggressive bear encounter.  There have been, however, cases where a rescuer shot the attacking bear and injured or killed the victim being mauled.

“…Bear spray has never killed a person or bear.”

The study was in press when an empty can of bear spray was found near an Alaska man killed by a grizzly on the Kenai Peninsula this summer. Investigators reported it was clear from the pepper residue at the scene that 46-year-old Daniel Schilling, an experienced outdoorsman, emptied the can before his death.

What exactly happened will, however, never be known for certain because Schilling was alone. And many people proficient in the use of firearms, as Schilling was, at times prefer to carry bear spray in Alaska for a variety of reasons.

Long-running debate

Among other things, spray is significantly lighter and less bulky than any firearm capable of readily stopping a determined bear. It does not require a very good aim to hit the animal. And it does provide protection against bears without killing them as the Lower 48 researchers noted.

Killing bears in self-defense in Alaska is legal – a candidate for a 49th-state seat in the U.S. Senate is now campaigning heavily on the basis of his once having done so – but the laws on defense-of-life-and-property shootings – or DLPs as they are commonly called – border on onerous.

Anyone who DLPs a bear is required to skin it, sever the skull and deliver it along with the hide to the Alaska Department of Fish and Game. For those inexperienced in skinning and butchering big game, this can take hours, and the hide of a large grizzly can weigh more than 100 pounds, a weight heavier than most people are capable of packing far.

On top of all of this, there is the danger of errant bullets as cited in the latest study.

A 26-year-old Anchorage woman afraid of bears last year borrowed a handgun from a friend before heading off on a solo backpacking trip into the Talkeetna Mountains. 

When she reached for the gun in her tent in the dark, it went off, blowing a .40-caliber hole in her hip and shattering the top of her pelvis before traveling down her leg and exiting out her thigh.

She was lucky to have a Garmin In-Reach with which to signal for help or she might have died, but there are plenty of people in the 49th state who have also been saved from maulings by the use of firearms.

And the death of Schilling, along with that of a hunting guide found dead after emptying a can of bear spray on a Wyoming grizzly in 2018, have raised questions about a bear-defense weapon once thought foolproof.


The unknowns in both of those cases make it impossible to say for certain whether the spray failed, and the new study underlines further variables that warrant discussion.

Researchers found that in some circumstances, such as strong cross or headwinds, the spray must be used at very close range. The spray’s range in some conditions was reduced to two meters or about six feet.

Between the rapid loss of pepper in the can and the short range, it is easy to imagine a scenario wherein someone firing too soon could lose the effectiveness of the spray to the wind while a bear was charging.

How likely one is to have a dangerous encounter with a bear in strong winds is, however, another debatable issue. Most bear attacks have occurred in sheltered areas.

“Bears tend not to be moving about in high winds because it decreases their ability to smell and hear,” the study says, citing the work of Canadian Stephen Herrero, a well-known authority on bears.

The study does, however, make it clear that in an encounter with a troublesome bear in wind or freezing cold, spray users need to hold their nerve until the animal is within feet before using the spray if it is to be most effective.

This appears especially true in very cold weather.

“Although cold temperatures significantly reduce the reach and dispersion of bear spray,” the study says, “the user can still defend themselves, though at close range (two meters).”

The study does not address how many people have the nerve to stand their ground until a grizzly bear is within about six feet.

“To mitigate this (range) limitation,” it does adds, “persons can carry bear spray beneath their coat where the warmth will keep pressures high and spray distance optimal. The trade-off, however, is that the user is less able to rapidly deploy the spray as when carried on the belt or pack strap.”

The same limitations and trade-offs apply in camp as when on the trail, but the researcher conclude that “in our opinion, (these) can be surmounted by the user managing canister temperature by keeping it in a warm place rather than letting cans of bear spray get cold.”

The study also says the four-year expiration date on spray suggested by most manufacturers appears to be a reasonable time for replacement.

“Our research shows that at four years, roughly seven to eight percent of the propellant will have escaped,” the study says. “This loss correspondes to a 40 percent reduction in head pressure given pressure depletion curves.”

Expired cans are good for practicing the use of spray, but they should not be used near other people – the pepper is noxious if you get it in your eyes or on your body – or in areas frequented by others.

Once out of the canister, the scent of the pepper has been known to attract bears instead of repel them, and any human wandering into an area that been recently sprayed can get the burning, often painful residue on their clothes or body.

Spray is not without liabilities, but the researchers concluded that given its “ready availability (it is easily carried in the hand or on the belt), rapid deployment, ease of use and non-lethal effect…we recommend that bear spray have a place in everyone’s bear deterrence tool kit.”














10 replies »

  1. On two occasions in high winds I almost stepped on bears that did not hear or see me. Lucky for me they stood up, did a little teeth clacking, ran off a distance and then moved on. I now ALWAYS carry an extra pair of undershorts in my pack.

    • On two occasions, I’ve almost stepped on sleeping bears. On both occasions, i managed to back out of there with the bears still asleep. I did not need clean undershorts, but it was close.

      It was also a reminder of why hunters who go sneaking around in the woods have a disproportionate number of bear encounters further confounding analysis of spray versus gun data.

      We have had people badly mauled, and one now possibly killed, because they couldn’t get the spray into action fast enough. I’d expect any number of the maulings of people carrying firearms – maulings which predate the arrival of spray by decades – involve similar situations.

      If you step on a bear at a matter of a few yards or even 50 feet, and it reacts by charging, there isn’t much time to react.

  2. I am not buying into the thought that using bear spray saves a bear’s life in Alaska.
    The opposite was seen this summer (and several times in the past) as the F&G biologists usually fly in and kill at least 4 bears everytime someone dies from a bear attack…if the person under attack was trained and ready with an appropiate firearm (like in the Medred bear attack) then that person can neutralize the “bad bear” while preventing further innocent bears from being slaughtered by AKF&G…not to mention it very well can save your life!

    • Never thought of it that way. The person on the scene knows exactly who (or what) in this case is attacking them. First responders have a harder time figuring out who the actual culprit is and may get the wrong guy (or critter).

    • interesting point i never thought about, Steve. it was similar in Wyoming, where they killed a sow and a fully grown cub. the cub might have run off and survived if the guide killed in that incident had shot and killed the sow at the time it attacked.

  3. It’s worth noting that the candidate for a 49th-state seat in the U.S. Senate campaigning heavily on the basis of his once having once killed a bear in DLP didn’t actually kill the bear, his hunting buddy did. Also anyone who DLPs a bear is required to remove the claws along with skinning it, severing the skull and delivering it along with the hide to the Alaska Department of Fish and Game. Something the candidate for US Senate nor his hunting buddy who actually killed the bear didn’t do.

    It almost seems like the conclusion of the study should have been to put the can of spray under your coat which would then cause you to delay getting to the can so you would be forced to wait until the last possible second to deploy the spray. In other words a built in delay and no need for the additional nerve.

    I finally bought a can this year and wore it while packing 100 pounds of meat on my back, I didn’t get attacked by a bear so it must have worked!

  4. I am going to call fallacy on this:
    “Bears tend not to be moving about in high winds because it decreases their ability to smell and hear,”
    While this is true, to a limited degree with most animals, it certainly should not be taken as gospel.
    20+mph winds can be and generally is the norm in many parts of Alaska and brown/grizzlies don’t even notice.
    I have been locked on and “challenged” by a big bore once on a sedge flat on Katmai. He came within 10 yards in the cowboy, pissing all over himself, etc.. in 25+ mph winds. My scent blowing right at him. I thought even with a shotgun, even being as prepared as one could be during an encounter, this could go to “Shitsville”real quick. Luckily he went back to feeding and I humbly retreated. I have had a couple very close encounters at Lake Clark and winds again were in excess of 25 mph.
    I am fairly certain bear spray would be of little use.
    I feel winds degrade us more than a bear. I have smelled bears that I have never seen. Without the wind youu cannot hear them.
    Plus, with no known predators (other then themselves) brown/grizzly bears have little to fear from the wind. So, I am claiming hogwash to that nonsense.

    I am even going to say if you are waiting 6 feet to spray a charging grizzly you are in a bad situation. It is utterly ridiculous to expect this as personal defense. Throw some “Black Magic” at them. Works every time.

    • I consider Katmai a somewhat unique situation. In areas where bears are regularly shot at, I’ve surprisingly never had a close encounter in windy conditions. They’ve all been when winds were light to calm.

      Some of those encounters have surprised me, too, because I’ve walked into bears that should have seen or smelled me but clearly didn’t. Sometimes, it seems, the damn animals just don’t pay attention.

      And I’d guess those at Katmai – especially big boars – have less reason to pay attention than any bear anywhere.

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