Some cats and birds can get along, but keep in mind that cats are predators and birds are prey. When the cat looks like it's ready to go after the bird, a sharp "No" should stop it in its tracks. Keep a spray bottle with only water handy if the needs more convincing. Never leave the cat and bird together by themselves. Place them in separate rooms when you are out of the house. Don't let the bird attack the cat either, use the same forceful "No." No guarantees, but with patience they may learn to tolerate each other. A few even become friends.