The male Wood duck’s extraordinary beauty defies description. Mark Catesby, who published observations of the flora and fauna of the southeastern colonies in 1741, named it the Summer Duck because it is the only duck that breeds in the southern United States.
Mr. Catesby suggested a charming Latin name: Anas Americanus cristatus elegans, “elegant American duck with crest.” Linneaus chose Anas sponsa, “waterbird in bridal dress.” James Rennie, writing in 1833 in “The Architecture of Birds,” described the male: “The beautiful pendent crest of the summer-duck arises from a base of glossy golden green, shading off into a rich violet brown, dashed with interrupted streaks of snow white. The feathers covering the wings are of the same glossy brown, which melts into black, with rich purple reflections of burnished steel; while those on the flanks are delicately fringed and striped with black and white. But, …words are not fitted to convey a correct notion of its varying and variegated colours….” And the author gave up, without noting its bright red eye and the bright red on its bill.
The female is a beautiful soft gray-brown with a distinctive white patch around her eyes and a hint of a gray crest. When the male molts into “eclipse” plumage in early summer, he resembles the female and the young. He is back in full regalia by mid-September.
Of the several ducks that nest in trees (Common and Hooded merganser, Common and Barrows Goldeneye and Bufflehead), the Wood duck is the only one that is true to a woodland habitat in all seasons, including migration. The Wood duck is a small to medium duck, with a slim body and large eyes adapted to flying through the woods without getting caught in branches. In 1885, when the American Ornithological Union developed its checklist, Wood duck replaced Summer duck as the official common name.
The Wood duck feeds on the surface of a pond, creek or river, paddling along quietly, pecking with its narrow bill at partially submerged vegetation. It is a fine swimmer and nimble overland hiker.
Without a strong enough bill to excavate nest cavities, it typically uses cavities created when a branch falls from a mature tree, creating heart rot in the trunk. Many old-growth trees were lost in the 1938 hurricane in the northeast. To compensate for the loss of potential natural cavities, artificial nest boxes were installed in the Great Meadows National Wildlife Refuge outside of Boston. The program was so successful that nest boxes are now common. Wood duck habitat was hard hit by Hurricane Katrina.
The Wood duck is native only to North America, its range spanning from extreme southern Canada, through much of the U.S. (except the arid west), and parts of the Yucatan in Mexico. Some populations live year-round in the Southeast and the Pacific Northwest. This once-abundant duck was brought to the brink of extinction by the turn of the 20th century because of excessive hunting for sport and table and because its prime habitats of swamps, wetlands and old-growth trees were replaced by development and farming. In 1916, hunting season on Wood ducks was closed. Fortunately, some Wood ducks had survived in remote swamps. After the passage of the Migratory Bird Treaty Act in 1918, the population began to recover and moderate hunting was eventually allowed. By 1990 the Wood duck had reoccupied and even expanded its original range.
Wood ducks that breed in northern climes begin migration by October, departing in small flocks just before sunset and flying through the night. They are monogamous for the season, pairing up with active physical and vocal courtship displays in the fall. Once mated, they winter together and arrive together on their breeding grounds in the spring. The female investigates suitable cavities by climbing around on branches of trees while the male watches nearby. Wood ducks often return to the previous year’s nest site.
Nests are usually at least 30 feet above ground or water and lined with wood chips and down plucked from the female’s breast. The number of eggs varies widely from 6 to 40. The latter number indicates a “dump nest,” in which eggs are laid by more than one female Wood duck or even a Hooded merganser. Dump nests are common when artificial nest boxes are installed too close together.
Only the female incubates the eggs; she leaves the nest twice a day for about an hour in order to feed. The young hatch after about a month. Twenty-four hours later, the female checks the nest area for predators. When all is clear, she calls with a soft “kuk kuk,” encouraging the nestlings to the entrance. With the sharp claws on their webbed feet, they climb up and, with wings outstretched, they drop to the ground, sometimes as far as 60 feet. They rarely hurt themselves regardless of the distance they fall. The female leads them to a protected watery spot where she supervises them for about five weeks. When sensing danger, the mother will warn the ducklings to hide and will perform a broken-wing display to lure away a predator. The young can fly by nine weeks.
The Wood duck is omnivorous, eating primarily nuts, fruits and aquatic vegetation. Its diet changes seasonally. Females need insects and aquatic invertebrates high in protein and calcium during egg laying. Ducklings eat invertebrates until about four weeks old, after which they switch to plants. In fall and winter, Wood ducks add seeds high in fats, acorns being a favorite. In a shallow pool, a Wood duck may dive almost a meter in order to collect an acorn. The Wood duck’s esophagus can stretch to allow it to swallow and store large nuts. One investigator counted 30 acorns in one esophagus.
Wood ducks visit the small ephemeral pond in Perkins Woods at Grant Street and Ewing Avenue in north Evanston in the spring, and there is a good chance of seeing them from April through September on a walk along the Chicago River in Harms Woods.