We feed the birds on the patio...it's the ground feeders, especially the doves, that the cats prey on. If you have shrubbery or flowers near where they feed, where the cat can stalk the birds, put up an attractive garden fence as a barrier. If they can't spring on the birds from hiding, they have an extremely difficult time.

Or, do as Argranade said, and move it away from the hiding spot.

Good luck to you and thanks for caring about the birds.