How many years shall I give the local foxes and coyotes to adapt? It's been over 30.

one or two shrews or voles per cat a month (about the limits of our "gifts") are hardly going to unbalance the local neighborhood ecology. The only thing left of the rabbits, squirrels , possums, woodchucks, chipmunks etc our cats kill are normally the tails, occasionally a foot. The cats seem to do a much neater and complete job about disposing of their kills then most of the local wild animals.

I do have to admit they will occasionally leave the wings of large moths - eating only the bodies.