On June 28 while waiting for friends to catch up, I sat at the JMT junction chatting with thru-hikers as we watched marmots and squirrels rifle thru a pack. They will definitely investigate and make off with anything edible. If you're hiking the JMT/HST etc you will have a bear can, make sure everything scented goes in there and leave it lined up away from the packs with all the other bear cans.
Also it's a bonus if you keep your pack & non-food gear clean of food spills & leaks, and even think of the salt from sweat (gloves, hats, pole handles) as a potential attractant...the critters in general seem almost as happy chewing on greasy/salty fabric or plastic as they are eating your food supply. Yesterday on Half Dome summit I confiscated an empty ziploc a squirrel was busily mauling...food was long gone but it probably had residual salt.