WOOD DUCK – Aix sponsa
The Wood Duck is a forest-loving, cavity-nesting, dabbling duck. It prefers habitats such as wooded wetlands and marshes, often constructed by beavers, as well as ponds and slow-moving rivers. When large conifers with dense, overhanging boughs edge these watery habitats, the Wood Duck gains at least moderate protection from predators. As the only duck species with clawed feet, it has considerably more mobility than other waterfowl allowing it to climb trees, roost on tree branches and nest and nurture their broods in tree cavities or wooden nest boxes.
The physical beauty of the male Wood Duck in breeding season is legendary, unique in many respects, since the species has no close genetic relatives other than the Mandarin Duck of eastern Asia. Smaller than a Mallard, the male weighs only an average 1.3 lbs. with the female weighing slightly less. The body length is close to 18.5 inches with a wing span of 30.” As strong flyers, they have been clocked at over 30 mph. During spring we see the male displaying an essence of color and line that suggests he has been artfully painted. In fact, female Wood Ducks have been choosing the most beautiful males as mates over millions of years; thus, the evolutionary process of natural selection has brought the male Wood Duck to this point of stunning artistry. During spring we marvel at his feathery iridescence, his round head with a drooping green crest and a red bill. A white bridle sweeps around his throat and neck and a wide, white stripe rides down each shoulder. His flanks and underside are bright yellow. Also a beautiful bird, the female presents a tawny, spotted breast and wider-spotted flanks. A white, teardrop-shaped pattern encircles her eyes.
Wood Ducks are omnivores, eating across a wide variety of available foods. With small bills, they forage in water by taking surface food or submerging their head and neck, occasionally up-ending and even walking on land. Their diets include duckweed, grass seeds, weed seeds, maple seeds, tiny crustaceans and fish eggs. On land they may walk considerable distances searching for grains, nuts and berries. During the breeding season the female has an increased need for protein to produce eggs. She therefore supplements with large quantities of shell-encased invertebrates.
In January the male Wood Duck performs his courtship displays and his new mate then chooses a nest for the couple – a tree cavity possibly as high as 65 feet or a nest box placed on a tree trunk. She may actually return to her original nesting site if available. Unfortunately, nest sites are in short supply for these ducks as more mixed conifer forests are being cut for development. This causes other species such as Hooded Mergansers, Common Goldeneyes, Northern Flickers and squirrels to compete for the same nest locations. In an ongoing effort to increase Wood Duck survival, landowners, environmental organizations and state and federal agencies are installing nest boxes for these and other duck species in appropriate habitats.
Once she chooses the nest site, the female and male do not begin lining it with feathers and moss as most birds do. Instead, she lays her first clutch of eggs and covers them with whatever material has been left in the nest. She then lays another clutch and covers it as well. Since Wood Ducks and a number of other duck species practice parasitic egg-laying, at this point a new female may enter the nest, deposit her own eggs and also cover them. This behavior may result in masses of eggs in a nest. Upwards of 60 to 80 eggs have on occasion been recorded in one nest by field biologists. The original female parent then cares for these large mixed broods. Whether the survival rate is even moderately successful is difficult to document due to the crowded nest conditions as well as invading predators such as raccoons, crows, owls, cats and hawks attacking the young.
The female lays 6 to 16 eggs and incubates them alone for 25 to 35 days while the male feeds her and protects the nest. Once the hatching begins it will take from 24 to 36 hours for all the chicks to emerge. A remarkable aspect of these hatchlings’ development is that they have been imprinting on their parents even while still encased in their eggshells, answering their mother as she vocalizes with low calls while she is incubating. The parents will lead the young away from the nest as soon as they are all dry, possibly as soon as only six hours. Now that they have bonded as a brood, in their heavy down insulation and with their precocity, they jump to the ground from their nest, hurry to the water following their parents’ calls and begin quickly feeding themselves. During this time the parents will defend the chicks against predators but will not feed them. If food is insufficient, Wood Duck families may need to search for new feeding sites, perhaps traveling up to 5 miles or more with their parents. Wood Duck broods have even been seen swimming across the Mississippi in search of food shortly after jumping to the ground from their nest. The female will stay bonded with her brood for up to 70 days. As to the male, in June he loses much of his brilliant coloring as he moves into molt. Though he loses nearly all his feathers, he keeps his red bill. Without feathers he cannot fly and thus must stay well hidden from predators until his new feathers appear. By January he is in full breeding colors again.
The highest densities of Wood Ducks in western Washington are near Olympia and the Vancouver to Longview segment of the Columbia River. Though we don’t have large numbers here in the West compared with the Midwest and East, researchers are observing that the species is slowly expanding its range toward us. In fall and early winter some of our local Wood Ducks may migrate to British Columbia or northern California; however, most of them remain in our general region. Should you be interested in observing these lovely birds as well as other waterfowl species this spring, a few mated Wood Duck pairs generally raise their broods in the wetlands around the McLane Creek Nature Trail. Look for the females escorting their surviving juveniles through the lily pads while the highly photogenic males roost and preen atop the water-soaked logs. This gated preserve, managed by the Washington State Department of Natural Resources, remains open dawn to dusk with a Discover Pass required for parking.
The survival of the Wood Duck and other waterfowl species has been perilous in the U.S. for at least 150 years. The Wood Duck itself became so severely threatened by uncontrolled hunting in the early twentieth century that the federal government banned the hunting of the species in 1918. That same year congress approved signing of the Migratory Bird Treaty Act. Later, the Bird Hunting Stamp Act of 1934 provided additional desperately needed protection for waterfowl survival. Finally, in the 1940’s the populations began to slowly increase under the aegis of the now 562 National Wildlife Refuges and 209 specific waterfowl production areas. Today the U.S. protects 150,000,000 acres devoted to wildlife and waterfowl protection.
Even with this progress, however, ducks continue to experience serious threats to their survival. Despite great care by the parents to raise their broods, high loss of waterfowl young is generally the case. This is evidenced by field biologists’ records of at least a 41 percent, possibly as high as an 80 percent, loss of Wood Duck young. The causes of this significant loss are complex. A portion of it is attributable to predation that various wildlife agencies attempt to control, though often with prohibitive costs. Deadly diseases also endanger high numbers of ducks. These include botulism, avian cholera, aspergillosis (fungal disease), and duck plague (duck viral enteritis).
A major looming threat to our Wood Duck population is an increase in urbanization to the point where their marsh habitats are vanishing due to over-development. Global warming also hovers as an over-arching threat. As the climate heats, Wood Ducks and all waterfowl will be in danger of wildfires incinerating their habitats. More specifically, as spring heat waves grow more intense, young ducks in the nest will be highly endangered. One of the most effective actions we can take to save these exquisite waterfowl species is to address climate change in our communities. Speaking up to save our wetlands is crucial.
Sharon L. Moore
Photo credit: Wikimedia Commons. ShareAlike 2.5. Robert Lawton
