1.   But now the decoy helps to preserve the duck population.

2.   At the same time, they have ensured the successful revival of a North American duck population that a decade ago was in serious decline.

3.   In fact, Heusman points out that duck populations are still well above historical highs.

4.   It was Mother Nature that caused duck populations to decline, and it was Mother Nature and her improved nesting habitat that brought them back.

5.   These areas are among the most important sites as they support the largest duck populations.