Make a dark roux with the oil, flour and seasonings. Add 2 cups water to make gravy. Allow to simmer while preparing next step. Chop vegetables and place in bottom of crock pot. Place ducks on top of vegetables. Pour gravy over ducks and vegetables.
Turn crock pot on low and cook at least 8 hours. Two hours before serving, de-bone ducks, return meat to crock pot, slice sausage and add to gumbo. Serve over rice, adding Tabasco, Worcestershire or any other flavoring to taste. (HINT: Tastes much better the next day after cooking.)