Changing habitat has complex consequences for birds. Some species prefer deep, old growth forests. Others thrive around patchwork clearcuts. Some require grasslands to breed, while others reproduce in swampy bottomlands. Some of our notorious losses—the ivory-billed woodpecker and Carolina parakeet—needed relatively narrow bands of Southern wetland so much that when the trees there were felled, the birds disappeared forever.
The wood duck was on its way to a similar predicament a century ago. Dressed like no other native duck, the population of Aix sponsa, roughly meaning “the duck fitted out like a bride,” was declining toward extinction. Hunting had taken its toll, as did the loss of old-growth trees and large, unfragmented forests. It is in the cavities of deciduous hardwoods—trees such as tupelos, oaks, maples, hickories and swamp cypress—that wood ducks nest; their toes are adapted with sharp claws to ease movement around their elevated homes. Recognizing the risk and seeing ourselves as both threat and hope, legislators and conservationists took action, providing protection in the form of the 1916 Migratory Bird Treaty and Federal Migratory Bird Act of 1918. A decade and a half later came the construction of thousands of nest boxes—large, low houses that still are built and placed in swamps, ponds and roadside wetlands. The wood duck recovered to historical population levels, still a visual delight in all its beauty.
We in Pittsburgh are lucky each spring to welcome back migratory ducks who appear along our rivers and at the edges of small ponds to surprise us with their splendor. The male wood duck, or drake, has some of the most striking plumage of any North American bird, with iridescent green, cinnamon and buff feathers, an orange and yellow bill, and a reddish eye ring. It’s a rainbow streaking by at more than 30 miles per hour. With the exception of a yellow eye ring and wings with blue, violet, and purple feathers, the female hen pales in comparison until her plumage refracts the light. Only then is her color evident, in some ways equal to the beauty of the drake.
The hen incubates the eggs high in a tree cavity or in a manmade nest box. Once her brood hatches, they claw their way to the nest opening and jump, sometimes plummeting 65 feet—occasionally nearly 300 feet!—to the forest floor (they’re downy and take a light bounce) before waddling behind mom to the nearest watery feeding ground. Large egg clutches and successful waterfowl management have ensured a comeback for this species. Still, in the face of competition for well-hidden forest canopy nest sites, some wood duck hens lay their eggs in shared nests, actually fairly routine in the species. Taken to extremes, the competition ultimately creates more losers than winners when artificial nest boxes erected in ponds and other wetlands can lead to ungainly and wasteful communal nests. These “dump nests” have low reproductive success, sometimes containing upward of 40 eggs, many damaged or inadequately incubated, often abandoned to avian or mammalian predators, or yielding only a few surviving ducklings. Despite these challenges, wood ducks are increasingly common in Pennsylvania, numbering over 100,000 breeding birds across the state, enough to allow some 20,000 to 40,000 birds to be taken annually by hunters. In Pittsburgh, a “woody” might rarely be found year-round, but with spring migration, now is the time to look for these marvelous ducks as they move our way from winter territory in the Deep South.