It’s not that easy for humans to determine how to manage the living wild environment, including both plants and animals. Lots of unintended consequences in every action.
This article describes a study that shows how deer populations interact with invasive species. This post has a positive take on multiflora roses, but be sure to read the comments. PA game commission has successfully reintroduced elk (starting in 1913), fishers (starting in 1994), and peregrine falcons (in the 70’s). The fishers are just now starting to be prevalent near here. They are nasty animals and I worry about my little dog.
Out west, we have the demise of the transplanted bighorn sheep (can’t you just imagine the mountain lions watching them being brought in and thinking “Snacks! Thanks!”). The success of the wolves in Yellowstone has led to a hunt, described here in most fatalistic terms. Of course, introduction of the wolves has resulted in a change in the way the elk are killed – less from human hunting, more from wolf hunting (22 per wolf per year!!). See this post. And this.