IF you are in a situation where cats are truely needed for pest control (i.e. rats and mice), then there is no need for them to be killing shrews, voles, rabbits, etc. In fact, aren't shrews mice eaters. Kinda problematic huh? And just because cats do provide some valuable pest control (i.e. legitimate barn cats) in some instances, it is foolish to assume that all cats everywhere should be able to kill indiscriminately. Cats may PREFER to hunt, but to repeat, the owner is suposed to be the one doing the thinking.