When I was visiting a friend who lived on the edge of a wilderness preserve, we drove along a rutted trail, and we saw a small creek ahead whose bridge was under water.
"We have a serious beaver problem," our friend said. "They build dams that cause the creek to flood. Forest rangers take down the dams, and the beavers rebuild them."
As we got closer, we could see a large scoreboard posted by the bridge.
It read: BEAVERS 3 RANGERS 0