bubblyrat, ranchers here in Alberta like that sign (and in New Mexico and the southwest U. S. as well), but nowadays it just brings laughs.
Pepper works to some extent, but gets expensive if the area is large. There are little fake chili pepins sold by plant sellers here, but reviews are mixed and they also aren't cheap.
Don't do what a neighbor up the street tried. He scattered mothballs in his plant beds to keep out cats. I found out about it when a child came to me with a handful and asked if she could eat them. When I told him, he spent almost a day making sure he had recovered them all.

Outside of doing your best to keep neighbors friendly, there is little that one can do if the area is open.