Okay, love the behavioural comments but back to your food situation.

Just to clarify, is it just that it only looks like they are carrying 2 pieces of food? Are you watching your food storage number when they get to the bin? Is it only going up by two?

If you are truly bringing in more than two bits of food then it just sounds like you have a graphic glitch. otherwise, hmm, stumped! Never saw that one before!