We know more about raising ducks and how ducks survive on the landscape than we do about any other animal in the world. We can measure the actual ecological production of waterfowl, for example, at a level that is not possible for most other species.
We know a lot about what types of landscapes can actually reproduce ducks and grow the fall flight of waterfowl, and that is why they're a really good measuring stick for biodiversity. We can understand how some landscapes produce ducks, and other landscapes don't produce ducks. That's why they provide a very good signature species for policy development. You can measure the results of your habitat work with ducks, unlike any other species.