Re. walnuts being a menace, here's my story:

My last house had a walnut tree in the back yard, so we had lots of squirrels. They were causing trouble; pulling up roofing shingles looking for something underneath to eat, building dreys on the roof and chewing into the house to shack up in the attic for the winter. So I started shooting them with my air rifle. 46 the first partial year I lived there and about 60 the year after. Problem was, no one was cleaning up the walnuts any more. Even eating them and leaving the mess like squirrels do breaks them down so they're not a hazard to step on. (unless barefoot) and I turned my ankle one time trying to mow the lawn. I had to start raking them up after that, because that was still preferable to repairing the house and evicting them from the attic.