You might sit the food bowl in the middle of a plant saucer filled with water. I don't think ants can swim … I know they use this method to keep them off of hummingbird feeders.
I have a colony of feral cats I feed daily and have a huge problem with ants. They don't seem to like to crawl in deep dishes. Plus, here's a good tip to use in the home. Sprinkle some cornmeal around the baseboard(and where you think they're getting in and other areas you see them). They take the granules back to their colony and die. It really works. It takes about a week before you won't see them anymore, but it's non-toxic to pets and it's well worth it! Good luck
ants don't like deep dishes and I would put their food dishes in a different location (perhaps somewhere higher in elavation) and sprinkle cornmeal where you think they are coming in. Would be good to sprinkle cornmeal also under their dish. Cornmeal is not toxic at all to them or children, it's cheap and takes about a week or so before you will see them gone. It doesn't hurt to also put a flat lid and a mound of cornmeal in areas you see them. Good luck~
Sprinkle cornmeal under the food bowl and where you think they are coming in. I have feral cats that I feed outside. It takes about a week or so, but eventually they take the granules to their nest/colony and die. Are your ferals altered? I don't know where you are, but hopefully theres a low cost clinic in your area. Tons have sprung up recently. You can borrow a trap from your local humane society. Good luck and thank you for feeding them!