Birds that have been bitten by cats need help immediately. Cat saliva contains bacteria that is usually fatal to birds unless appropriate antibiotics are administered very soon after the injury. Cat predation is a major threat to bird populations, especially those already on the decline due to habitat loss. Please keep your cats inside - for the safety of both your pets and the birds.
For more information, see:
Although keeping cats indoors is the best practice, a compromise for pet owners who are unwilling or unable to do so is a bib that reduces successful pouncing; it is sold by Cat Goods, Inc.