I've read that in the western US, backpackers need bear canisters or bear bags, for bears or for other animals. For example, a post comparing different methods is here. I must admit I'm a bit daunted, because on my European trips I've never given the slightest worry to animals (food lying around right outside my tent, along with my stove). The Forest Service states that the food should be in the container whenever you are not actively preparing, eating or unpacking. Do I really need to keep my food in one of those while hiking? Are bears or other animals so agressive?
Bear canister, Wikimedia Commons
My hope was that perhaps there are foldable canisters, and while I might struggle to pack my food volume-wise, this is not a problem during the night.