Hanging by throwing a nylon cord over a tree branch is good against most any animal if done carefully, in my experience. A basic outdoor book will show you how. Map the location, or mark the spot where you need to step off trail with a cairn. If you are just going to hide food in reused plastic containers, try rinsing them out with bleach solution first. Ravens will dig through a foot of snow.
Cairns can work above treeline.
Do map and mark as necessary. In my experience, memory can't necessarily be trusted to remember caches. In bear country, I've also cached plastic bags of food by weighting with rocks in a stream at times, but I can't say if I've just had luck or if this is a good approach. Hope this gives you some ideas. Several people have mentioned the standard trick of hanging food from trees.