If you think squirrels just hide a bunch of nuts and forget where they put them, you aren't giving them enough credit.

One study done in a small sample of Eastern Fox Squirrels show that they likely have a whole system to hide groups of nuts in different places based on their type. 

So, for example one of the tools in the squirrel's nut finding toolbox could be hiding one type of nut closer to a tree and stashing another type of nut further away so they could remember the hiding spots more easily late, which is similar to a pneumonic memory tool we use called "chunking." So, basically slotting information into groups. A great example is spelling out or saying your name in pause increments of about three, like "S-A.., V-A-N.., N-A-H."
And if a group happens to spell something familiar like "van," it's easier to remember, because we associate it with something, like an actual van, and give it meaning.

So, when squirrels put more valuable nuts further from the tree where they found them, they could be using their smarts to remember where they're hidden.