In Kerrville, a 4 foot fence wasn't tall enough to keep out the foxes (or the dogs, for that matter on one very sad day).
However, we've never had anything jump a 6 footer, although a bobcat stalked around and around once seeing if he dared. We see evidence of larger animals and know that the property is host to wolves, coyotes, bobcats, and more, but they really don't mess around in the homestead area.
Hawks, on the other hand....that's been a problem. I think we should consider a topper this time.
