Cats are hunters. You can't change it, it's their nature.
Sachi had never really been outside except for in her carrier on her way to or from the vet. I decided she would be a indoor cat when I realized shortly after she came home that she was deaf. She also had a cold and infected eyes. The medication for those problems cleared up her hearing as well. I'm not sure how well she hears now, but, thinking an indoor cat was a safe, long lived cat, I figured she could stay indoors forever.
Don't think it's going to last. She made a break for it last week. Bolted out the door as I was coming in and scampered away when I called her. Fortunately, it had snowed about 6 inches the day before. She looked at the weird white stuff. She sniffed it. She touched it with her paw. Then she tried to walk on it and sank in up to her armpit.
Eeek! Scary! Gross! Wet! Cold! In house good!
I held the door open and she ran right in.
Since then I've taken her out and stuffed her in through the cat door a couple of times so that, in case she does get out, she'll know how to let herself back in. She can't get out through the cat door because she's not wearing a magnetic key like Kitsu (tricky, eh?), but in is available to anyone/anything small enough to fit through the hole and willing to push.
One of her hobbies is a true cat hobby. She sits on the window sill, skulking behind one of the uprights, watching the birds at the suet feeder. Her intensity is frightening. She quivers, she lashes her mighty kitty tail. When she can't hold it in any longer, she utters strange staccato noises and tries to teleport through the glass.
How does she know what birds are? How does she know that she has to catch them and rend them feather from feather?
Instinct. It's amazing. Frightening too.