Overhunting by sportsmen and market hunters undoubtedly had a huge effect on waterfowl populations, but they would have largely recovered once market hunting ended and seasons and limits were imposed. However, massive conversion of wetlands to agriculture, both in the northern breeding grounds and the southern wintering areas, limits duck populations to the pale shadow of former numbers that we have today.
Snow geese are an exception that prove the rule: they breed on the tundra far north of agriculture, so have not lost breeding habitat, and winter in agricultural areas that provide plenty of waste grain. Due to abundant winter food, their population has exploded. The Aleutian goose is another example: once introduced foxes were removed from its breeding islands, populations went from nearly extinct to pest status in their wintering area. In both cases, liberal limits and long seasons barely put a dent in numbers.
