Here is a bunch of little ideas.
1. Cows and Soil.
Cows slowly raise quality of soil beneath them.(secret is in feces)
2. Wolves.
You can see them in two variations:wolf pack - 3-5 wolves(they must be a little bit more powerful than fox) or a one lovely wolf, as strong as a bear and very rare.
3. Traps and Nets.
From the history we know that hunters used some traps to catch their prey. One of them was a special trap - силок in Russian - that was used to catch birds. Other tool - net - was used to catch bigger animals. Hunter fixed a net between trees and then drived prey into it.
4. Deadly swamps.
Easily - some swamps have areas in center of them. If you`ll step into it, you`re dead.
P.S. sry for my Engrish.