Blue Jays stay here all winter even though foraging is hard with all this snow. They manage by stashing snacks in times of abundance. I’ve heard that caching bird brains expand during autumn when they begin caching – so they can remember thousands of secret locations spread out over several kms and what’s hidden in each spot.
If a Blue Jay feels some one watching him while he hides a peanut he’ll pretend he didn’t notice and come back later to move the treasure, but they only think to do this if they themselves have stolen some one else’s stash.
The Biophilium 