It's getting so frustrating I'm on the verge of looking for someone else to take both my cats. I know that sounds bad but I've got a chronic condition that means I've got very little energy to do the normal things never mind cleaning up cat vomit all the time. Today we have the bottom half of a mouse in the conservatory and cat vom all over the washing machine! I've cleared the mouse but had to step away for a breather as was nearly sick myself! Any advice??
Keep them inside overnight. Get them inside and feed them, and feed them again in the morning before you let them out for the day.
Also, toys help. Our two go nuts for a bouncy ball - you only need to chuck it once (down the hallway is the best place) and they entertain themselves. The other thing they love is the plastic wrap that goes around the top of Ben & Jerry's cartons! As soon as I get a tub out, my cat is all over me for the piece of plastic and it entertains him for days.
Cats love to hunt but it doesn't have to live animals - toys, feathers, bits of string, shoelaces, ping-pong balls, scarves...anything that moves quickly and can be dangled normally does the trick!