Scent Marking

[Permuted]

I'm fairly sure that's what she was doing. It's an interesting bit of fox behaviour.

[ScottieDM]

In his book, Red Fox: The Catlike Canine, David Henry did a lot of observation of and experimentation with wild foxes. He said when they cached food then came back and ate it later, they left a little sprinkle of urine to show the cache was empty. He speculated it's so they don't waste time checking old caches.

Looked like a food dish she marked. She might have been marking that it was empty.