Mallard

As the ancestor of the domestic duck, the Mallard could be considered the most successful waterfowl species in the world; its genes are everywhere! The wild version is widespread in its own right, occurring throughout much of North America and Eurasia and introduced into several parts of the southern hemisphere. Despite this wide range, it was not originally native to most of eastern North America, and populations here have only taken off since the mid-1990s. Much of the early increase has been attributed to deliberate introductions from game farms to provide hunting opportunities.

You can see this increase in the Mallard population graph, but this same graph shows a steady decrease starting around the year 2000. It’s not clear what’s behind this more recent trend, but a deeper dive into the data suggests that Mallards are declining in southern New England and the mid-Atlantic but increasing in northern New England and southern Canada. If such is the case, New Hampshire is caught in the middle, perhaps with a stronger link to whatever is going on to our south. Given the adaptability of Mallards it seems unlikely that urbanization is a significant threat, but perhaps there are corelated effects associated with toxic chemical or other pollutants.

Have you ever wondered where the unmistakable green-headed male Mallards have disappeared to over the summer? It turns out that they’re hiding in plain sight in something called “eclipse” plumage. Eclipse males look very much like females (you can distinguish them by bill color) and obtain this plumage in two stages. They first molt their body feathers to look more like females, and then lose all their flight feathers at once. Until these regrow the birds can’t fly, and their more subdued coloration keeps them safer from predators during this vulnerable time. Once they regrow their flight feathers they molt back into their bright breeding plumage and are ready to start attracting a mate over the fall and winter. Most ducks do this (including females, where it’s simply less obvious), so see if you can pick out the eclipse males of your local species during July and August.