BLANE KLEMEK COLUMN: Wood ducks always welcome in the spring
The little natural environment lake behind my house, Assawa Lake, was ice free on March 31, one of the earliest ice-outs in recent memory. Yet even before the lake ice was completely gone and the only open water available was the iceless perimeter lakeshore, a certain species of duck seemed to appear out of nowhere welcoming the coming the northland's early spring. Wood ducks had returned once again.
The drake of this remarkable species of waterfowl is capable of dazzling any otherwise earth-tone landscape void of brilliant colors and is certainly a sight for color-starved eyes. Arguably the most beautifully plumaged bird in North America, wood ducks are an arboreal species of duck—as odd as it seems—that perches on tree limbs, nests in tree cavities, whistles instead of quacks, gulps down acorns with relish, and can fly through flooded timber or an upland forest with the ease of a ruffed grouse.
As mentioned, wood ducks are cavity nesters—that is they routinely nest inside holes in trees. But they are not the only species of waterfowl to do so. Buffleheads, common goldeneyes, common mergansers, and hooded mergansers are other species of North American waterfowl that nest in tree cavities, too. And while some of these species of ducks will readily use artificial nest boxes for nesting, it's the wood duck that has benefited the most from these human-made structures.
At the turn of the 20th Century, wood ducks were a species in peril. Unregulated hunting and habitat loss were reasons for their population decline. However, with timely legislation designed to protect migratory species—along with regulated hunting, habitat management, and the placement of nesting boxes throughout the birds' breeding range—wood ducks have made a roaring comeback from those woeful times.
The wood duck's recovery, or mere existence for that matter, could never be possible without adequate nesting and brooding habitat. Indeed, this is the case for any bird. Nevertheless, for this specialized duck the presence and abundance of trees is essential to their survival.
Wood ducks are just one of the reasons why wildlife managers encourage private landowners to leave dead trees (snags) standing, especially when located near wetlands in prime wood duck nesting habitat. In the Midwest, some 26 species of mammals and 43 species of birds use snags as nesting and perching sites. Snags are also used as food sources and for territorial reasons. The best and most often used snags are large, usually over 15 feet tall and are at least six inches in diameter.
After a mated pair of wood ducks has selected a suitable cavity, a hen will begin to lay her eggs, one per day. Wood ducks do not gather nesting material like many birds do to build a nest. Rather, they rely on wood chips and natural woody debris commonly found inside natural cavities for their nest bowls. This is why one needs to add wood chips or shavings to artificial nesting boxes.
The average clutch size is 10 to 12 eggs, but can vary from six to 19. I once monitored a nest box where a hen sat on 21 eggs. Curiously, wood ducks will often dump eggs into other cavities for other hens to incubate, a form of brood parasitism. For this reason it is advised to place wood duck nesting boxes out of sight from each other. Some research indicates that boxes placed in plain view from one another encourage "dump nesting" among wood ducks.
After an incubation period of about a month, the ducklings hatch and leap from their nest cavity and either plop into a wetland or bounce on the ground below to join their calling mother. Once all the ducklings have left the nest, the hen will lead her brood to the relative safety of water where they will immediately begin searching for food.
One can easily imagine serious injury occurring to ducklings as they hurdle themselves from cavities high in trees. Surprisingly, the hatchlings have little to worry about. Their down-covered bodies help to cushion any blows they may encounter on the way down. Even their webbed feet, with toes all spread out, act as miniature parachutes to further aid in slowing their descent.
Just a few weeks ago I cleaned out my assortment of wood duck nest boxes that surround Assawa of old nesting material, including squirrel nests. It's an enjoyable annual chore that provides me opportunities to monitor last year's wood duck and hooded merganser production and to assess the condition of individual structures for performing any necessary repairs and to replenish the boxes with fresh wood shavings. Indeed, if you have nest boxes on your property there's still time to do a little "house cleaning" of your own or to install new boxes.
According to the DNR, more than 100,000 wood ducks breed and nest in Minnesota each spring. Thanks to efforts in conservation biology and wildlife management, wood ducks are abundant as we get out and enjoy the great outdoors.
For more wood duck info, visit: www.dnr.state.mn.us/birds/woodduck.html