When I was roaming about the Highlands of Scotland last summer my niece and I got a kick out of some of the signs. SLOW DUCKS. NO WHITE LINES FOR MILES. But our overall favorite was the one with the triangle with the bold exclamation point, of general alarm or warning, with the explanatory sign attached below.
                           x
                         x x
                         x ! x
                        xxxxxxx
                     RED SQUIRRELS
We had no idea whether they were six feet tall, or carried assault rifles, or what.
Years ago when we put up a "squirrel-proof" feeder with the perch that drops down closing the door when a weight pushes on it, to shut off bigger birds and squirrels. In twenty minutes flat I looked out and there was a squirrel lying on his belly, holding the roof ridge with his hind feet, reaching down to grab fistsful of seed.
Now we have (among assortments) one feeder hanging on a very thin post, with a clear acrylic dome over it, which lets the little chickadees and such feed safe from the roughlegged hawks and neighborhood cats, and another box-type of wide mesh that the squirrels and woodpeckers like. If you put in multiples, make them multiple kinds and you are likely to see a wider variety of clientele.
I did hear a rustle at night a while back and looked for a presumed mouse, and saw a critter I took for a squirrel pup scoot across my living room about six feet from me. I went to toss a beach towel over him to get him outside safely, and he ran up a bookcase and glided off. Twenty plus years in this house in the woods, and the first flying squirrel I have ever seen in the wild is in my living room.