There's really no way of stopping or reversing this without billions of people dying. Since the end of WWII, killing others for the survival of your own kind has become extremely taboo (outside of Israel, that is), so nothing is going to be done until it's way too late.
Well the world population is expected to stabilize around 10 billion or so for a long while. So that new normal may also stabilize the wild animal population. The exponential population growth of the past 100 years seems to have stopped so that is one good news.
