The group of four weren't carrying heavy backpacks like you might expect when foraging for materials, no they had thin ones along with many smaller satchels around their bodies so as to reduce the restrictions on movement as much as possible. They could also have an impromptu camp nearby where they'd stash the larger loot once the bags were filled. It'd be really inconvenient to lug around a dozen pelts, bones and who knows what else while hunting. Frost expected he might have to search the surrounding area for a base camp, but he ended up quite lucky.