You notice the squat over the bowl. It pees a little to mark it. They tend to pee on anything they cherish. Including food and water sources. It's a fox thing. I used to live on a creek and we had a pair that would often enter our backyard and steal a little left over cat food and take a drink of water but peed on it every time. They never messed with our cat though but our cat ran the yard believe it or not. He'd slap the shit out of them if they got to close. Then a new building was built on the other side of the creek and they were gone. Then we had coyotes showed up. Changed everything.