I have heard that the Opossum is a great enemy of copperheads. I live on nearly two acres in an established suburban area, but close to several patches of woods and swamp. (This means there are deer within a half mile or so of me, but not in my yard or block.) My belief is that black snakes keep down the rat population. Unfortunately, most of the snakes I see are dead. I try to provide them with a little cover.


Pythons, among other non-native species, are thriving in the everglades.

http://www.miamiherald.com/2009/09/2...verglades.html