Answer: I would consider the possibilty of raccoons or oppossums too. I have never heard of cats eating tomatoes (there's always a first, and you know cats do as they please!) and birds usually peck fruit but don't carry it away (a crow may be an exception).
You did not mention the damage you found on the fruit. Was it pecks? How much was eaten, or was any eaten?
It sounds like placing a netting over your plants is an option for protecting them. These can be a bit of a pain, but can also save fruit. If the culprit is 4 legged, a low electric fence may work. I have had success with one wire about 4" high and a second about 12" high.
Good luck with your tomatoes!
Q&A Library Searching Tips