38 years ago, I took this photograph of an American Black Duck nesting in a special nest box installed in Hassocky Meadow at the Ipswich River Wildlife Sanctuary in Topsfield.  At the time, it was recognized that the Black Duck was in decline and that a restocking program was started with the help MassWildlife. Black Ducks from Newfoundland called “Red-legs” were released at IRWS to fortify the gene pool of local Blacks with the purest of its genotype.  The Red-leg is the darkest, most red-legged and is a cavity nester. The program failed because the Mallard, which bred with the Black Duck had dominant genes and also absorbed some of the Black Duck’s tolerance for living in salt water.  This allowed male Mallards to breed with Black Ducks in the spring while on the coastal waters.  The Black Duck has since been slowly reabsorbed back into its Mallard historical parentage.