Blane Klemek column: Wood ducks recovered from brink of extinction
I spent the first Saturday of April visiting each of my 17 wood duck houses.
It was a beautiful day; warm and sunny. Pulling a sled loaded with a bag of wood shavings with one hand and a carrying a ladder with the other, I struck off across ice-covered Lake Assawa to do the job.
It was slow going, but enjoyable. The north side of the lake still had plenty of snowdrifts that were soft and deep. Yet the lake ice, which only days before was white with a heavy blanket of snow, was now covered in a sheet of ice. I was glad I decided to slip into my knee-high rubber boots.
Throughout the afternoon as I walked around the lake and climbed the ladder to clean out each of the wood duck boxes, I was thrilled by the sights, sound and scents of early spring. I heard sandhill cranes vocalize nearby, I saw a few robins, I heard a killdeer and I watched a pair of trumpeter swans fly overhead. Indeed, the day was full of springtime promises. It was good to be outside.
But out of 17 wood duck houses, only a half a dozen were used last year by wood ducks and hooded mergansers. The remaining boxes were either used by gray and flying squirrels or were not used by anything at all. Even so, this has never been a big surprise to me, because Lake Assawa simply isn't the type of lake that wood ducks find all that desirable.
While nesting habitat (natural tree cavities supplemented with a smattering of artificial nest boxes) and food are plentiful, brooding cover is in short supply. Nevertheless, I dutifully maintain my boxes each year in hopes that if I can get one or two additional pairs of wood ducks or hooded mergansers to nest successfully, then maybe the following season I'll observe a few more of these delightful species of waterfowl, but especially "woodies,"
Aix sponsa, the wood duck's scientific name, is a fascinating and striking duck, particularly the drake. It occurred to me while performing the nest box maintenance chores, that here's a bird that has the best of many worlds. Not only can wood ducks do the things that all ducks can do, they have also adapted to an arboreal lifestyle. In other words, the wood duck, as its name so aptly suggests, is at home in the trees, too.
I remember years ago on an early spring evening as I strolled around a wooded wetland at the Wetlands, Pines and Audubon Sanctuary that I formerly managed, when I was alerted by the sounds of two drake wood ducks in flight with a lone hen. Barely audible were their series of whistles and peeps, along with the hen's loud and well-noted distress calls, "hooo-eeek, hoo-eek!"
A few moments later as I continued my walk, I stopped to listen. High above me I heard more peeps and whistles. Sure enough, in the highest branches of a mature cottonwood tree, were several pairs of perching wood ducks. The birds were acting nervous that I was standing below them, and they soon flushed. I watched as the agile ducks expertly dodged the thick tangle of limbs, flight feathers slapping branches as they flew, in their haste to escape.
While the wood duck did not have it so easy around the turn of the 20th century, they are quite numerous today. In fact, some conservationists feared that because of rapid habitat depletion and overhunting, the wood duck would eventually become exterminated. Thankfully, in 1918, the Migratory Bird Treaty Act was passed.
This act protected the wood duck from hunting until 1941 when some 15 states began allowing one wood duck to be harvested per legal bag limit. Other states soon followed. Yet the wood duck's problems were not over with. Though making a slow comeback as a result of restrictive hunting regulations, the destruction of habitat, principally nesting habitat, proved to be the primary limiting factor to the species ultimate recovery.
Over the years, through critical habitat preservation and enhancement and carefully regulated hunting season, along with constructing and placing artificial nesting box structures in prime breeding habitats, the wood duck is plentiful in the 21st century.
Wood ducks are cavity nesters. They are not the only species of waterfowl that routinely nest inside cavities of trees. Other species include bufflehead, common goldeneye, common merganser and the previously mentioned hooded merganser -all of which nest in naturally occurring tree cavities and artificial nest boxes. But it is the wood duck that has benefited the most from artificial nesting boxes.
The average clutch size for a wood duck hen is 10-12 eggs, but can vary from six to 19. Wood ducks will often lay eggs into other cavities and nest boxes for other wood duck hens to incubate. This practice, which is a form of brood parasitism, is often simply called "dump nesting." After an incubation period of about a month, the ducklings hatch and leap from their cavity and either plop into the water or bounce on the ground below to join their calling mother.
For sure, the wonderful wood duck, a duck that whistles instead of quacks, a duck that relishes acorns, and a duck that can fly through forests, perch in trees in forests, and even nests inside of trees in forests, is yet another good reason to get out and enjoy the great outdoors.
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at firstname.lastname@example.org