Several here don't agree with having an outdoor cat. I have tried to bring our outdoor cat in...she won't have anything to do with that! She is happy to stay outdoors. I have never witnessed her kill a bird or rabbit. I have a bird feeder near the deck, and was concerned when she first arrived on our doorstep. The birds aren't afraid of her, as they are on the ground at times. I have watched her from the kitchen window at times when she didn't know I was looking, and she has never approached them. The only antics I have seen her do is poking her paw down a mole hole, and playfully jumping around. I feed her twice a day (early morning around 5 a.m. and late evening when I get home). During the day she sleeps and as I still have an array of birds on my birdfeeder and feeding also on the ground, I assume they do not feel threatened.
Last winter I was concerned with the cold, snowy weather we had, and like I said, I tried to get her in the house. She had a hiss-fit, so I can't see bringing her in the house. She has a couple of garages she goes in and being an outdoor cat, she has a survival mode, and she knows she gets fed well.
As for being feral, I have no worries about that. She pretty much I think knows she has it good, and she doesn't stray any more.