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Bears and food storage

Ursack

Also called bear bag, soft-sided bear bag

What is an Ursack?

An Ursack is a soft, flexible bear bag made from cut-resistant fabric that ties to a tree instead of being a rigid container. It's much lighter and more packable than a canister, and it isn't accepted everywhere canisters are required.

Ursack at a glance

Fabric
Cut-resistant UHMWPE weave
Weight
Roughly 8 oz against 2 to 3 lb
Accepted
Only where explicitly listed

What an Ursack is

An Ursack is a sack of high-strength cut-resistant fabric, in the current models a UHMWPE weave, with a cord closure. Tied properly to a tree trunk, a bear can maul it without tearing through, so the food stays contained even though the bag deforms.

Why people carry one instead of a canister

The appeal against a canister is obvious: far lighter, packs flat when empty, and shapes itself to whatever space is left in your pack instead of dictating the shape of everything else. On a long trip that's a real difference in both weight and volume.

The two caveats

Two caveats matter. First, contents get crushed even when the bag holds, so anything you'd rather not eat as powder needs protecting, and an odour-proof liner is usually recommended alongside it. Second, and more important: acceptance varies. Some units accept certain Ursack models, others require a hard-sided container and explicitly don't allow soft bags. It's the same rule as everywhere else in food storage, which is that the land manager's current list is the only authority worth trusting.

What this means when you're choosing

  • Whether the specific unit you're visiting accepts the model you own
  • The correct tie-off, since the bag only works if it's secured properly
  • An odour-proof liner, which most guidance suggests using with it

The common mistake

Assuming it is accepted where canisters are required

It is a different product class and many units that mandate a canister do not list it. Where it is allowed, tie it correctly to a live trunk with the knot the maker specifies; tied wrong, it comes away with the bear.

Common questions

Is an Ursack allowed instead of a bear canister?

Sometimes, and it depends entirely on where you are. Some areas accept certain models and others require a hard-sided container. Check the specific park or forest's current food storage rules before you rely on one.

Do I still need to hang an Ursack?

No, it's designed to be tied off to a tree trunk at ground level rather than hung. Follow the manufacturer's knot instructions, because a poorly secured bag can be dragged away whole.

Where this is defined

Where this comes up

Guides on Tom's Hiking where ursack changes which product is right for you.

Going deeper

More in bears and food storage

Bear canister

A bear canister is a rigid container with a lid a bear can't open, used to store food and scented items overnight. Many parks and wilderness areas require an approved model, and where they do it's a regulation rather than a recommendation.

IGBC certification

IGBC certification is the Interagency Grizzly Bear Committee's testing programme for bear-resistant products. Containers are tested against live captive grizzlies and by mechanical means, and passing earns a certification number many land managers reference.

SIBBG

SIBBG is the Sierra Interagency Black Bear Group, which coordinates black bear management across Yosemite, Sequoia and Kings Canyon, Inyo National Forest and neighbouring lands. It maintains the allowed food-storage container list used across much of the Sierra Nevada.

Bear-resistant

Bear-resistant is the accurate term for certified food storage: the container holds up against a determined bear for a defined test period. Bear-proof is marketing. Given enough time and motivation, a bear can defeat almost anything.

Bear spray

Bear spray is an EPA-registered aerosol deterrent that fires a wide cloud of capsaicin and related capsaicinoids, at 1.0 to 2.0 percent, into the face of a charging bear. It's a last line of defense carried in a holster, and it isn't the same product as personal pepper spray.

Calorie density

Calorie density is how many calories a food delivers per ounce of weight. Backpackers use it to keep a food bag light, because fat carries about 9 calories a gram against roughly 4 for carbohydrate and protein, so an ounce of nut butter carries many times the calories of an ounce of fresh fruit.

Electrolytes

Electrolytes are the minerals, mainly sodium, potassium, magnesium and chloride, that carry an electric charge in body fluids and help keep water balanced. Hikers lose them in sweat, and on long, hot days they need replacing with salty food or a drink mix, not plain water alone.

By Tom · Last reviewed . Back to the glossary