I think they must communicate in some way. I put out peanuts in the feeder. Before I know it, the few birds turns into a lot of birds and squirrels. I imagine them talking in the woods, Hey she put out the nuts. :)
Hey, I suspect they use the post-it notes like the squirrels do........don’t you love it? The squirrels hide all over my patio/carport. I see nuts in the cutest places. It just always brings a smile to me. They bring those big black walnuts and they are hard to hide~~~~~