My parent's planted five trees in their backyard about 20 years ago. Now, they are huge and their yard, if you ignore the fact that they have neighbors, can be imagined as a park. It's missing a water feature, but that doesn't seem to keep the birds away.
I imagine the squirrels waking up and saying, "Hey! Let's go to Park Hoffman today!" The rabbits have their turf, the squirrels have theirs, and certain birds frequent certain trees and/or bushes - it's like the high school cafeteria all over again.