When I hear such questions I personally step back and try to see the big picture. Where are these value judgements coming from? Are they valid?
I have to think that the process of natural selection and evolution are still at work. We have not graduated from them. Forces are at work that transcend the human specific concepts of what should or should not be occurring. I think in the larger picture everything is as it should be. I think our value to recognize this is a major problem in how we deal with ourselves and the world we find ourselves in. The whole idea that the species is defective, broken, or poisoned ignores the larger reality of the natural systems and processes that we are actually apart of, rather than the mental constructs and dreams of how things should be. It seems the better strategy is to accept and embrace who we are and deal with it accordingly rather than bemoan our inescapable nature. If we could channel our aggression, greed, and selfishness to get us off this planet and populating the solar system instead of fighting over patches of dirt down here it would be nothing but a good thing.
But yeah, a sign saying, Stay away, Dangerous Animals, Do not Feed the Humans probably wouldn't be out of order.