The story goes that Mexico wanted a demand met in return for the U.S. demand for waterfowl limits and seasons concessions. They came up with a crow proposal to satisfy their machismo. The places I have hunted ducks in Mexico have been pretty devoid of any enforcement. I did witness the shooting of a couple of wild muscovy ducks that were a protected species. They were referred to as Royals and are indigenous and protected. That mistake caused quite a stir with the guides whose boats were full of corn at the time.