In the following context, I understand the meaning of "slops being wrinkle with a maze of new deer trails." I just don't understand why does the writer say that. In other words, I don't understand what the writer is trying to say. Is he saying that deer are migrating toward the south? Then why they do?

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> Since then I have lived to see state after state extirpate its wolves. I have watched the face of many a newly wolfless mountain, and **seen the south-facing slopes wrinkle with a maze of new deer trails.** I have seen every edible bush and seedling browsed, first to anaemic desuetude, and then to death. I have seen every edible tree defoliated to the height of a saddlehorn. Such a mountain looks as if someone had given God a new pruning shears, and forbidden Him all other exercise. In the end the starved bones of the hoped-for deer herd, dead of its own too-much, bleach with the bones of the dead sage, or molder under the high-lined junipers.
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Context: [*Thinking Like a Mountain* By Aldo Leopold](http://www.eco-action.org/dt/thinking.html) 

Also, in what group can my question be classified?