Wood ducks are cavity nesters who are totally incapable of creating or even enlarging a nesting hole in a tree. Therefore, they are entirely dependent on what they can find. And they need a large cavity since they are big birds. Large cavities are made only by flickers and pilleated woodpeckers. Sometimes, a suitable cavity will form naturally in an old, rotting tree.
Early in this century the wood duck was nearly extinct but man-made nest boxes have helped them make a remarkable recovery, especially during the last 40 years.
Chris and I have five nest boxes on our pond. We chopped holes in the ice to drive in steel posts to which we mounted the home-made wooden boxes.
This March 25th a mated pair arrived at the pond. We'd been expecting them. Another pair arrived the next day and another pair the day after that. Many more will arrive during the next couple weeks after having made the 1000 mile sojourn from their wintering grounds in Florida. By now, pair bonds have been established and the life cycle is beginning anew.
This scenario has repeated itself every spring of the 25 years we've lived here. Oh, it's not the same ducks returning each year, of course. A woodie's average life span in the wild is only about 4 years. But the female progeny return again and again. Wood duck hens generally choose a different
mate each year. The chosen drake then follows her to her nesting site
during the spring migration. Consequently, the drake’s migration
destination may vary greatly from year to year but hers is always
the same. And it's always a thrill for us when these beautiful birds return to our pond.
Female wood ducks remember where they were hatched and will bring a mate to that same cavity every spring. If the cavity is already being used she'll find another cavity close by.
During winter we clean out the boxes to make sure they are fit to host a family. We replace the bedding with fresh cedar shavings and make any necessary repairs.
Starting in early May, the female lays a single egg per day. The nest usually ends up having about 15 eggs swaddled in down plucked from her breast. The male accompanies her to the nest each day and stands guard while she completes her task. Once the eggs have all been laid, incubation begins and usually takes about 30 days.
Sometimes there will be as few as 6 eggs in a nest and sometimes as many as 40 because some of the eggs were laid by other females. If a female can't find a nest of her own she'll lay her eggs inside another hen's nest. This is called dump nesting. When cleaning out the nest boxes in winter I sometimes find whole eggs or dead chicks in the dump nests. This is because once the hen and her own brood leave the cavity, they don't return.
Dump nesting occurs where nests aren't visually isolated from each other. The five boxes on our pond are within sight of each other so hens will observe other hens entering cavities to lay eggs and will then follow suit. Those that dump eggs typically incubate them later in the nesting season. Thus, she doesn't "put all her eggs in one basket" and increases her odds that one or more of her eggs will survive. Dump nesting has proven favorable for wood ducks and thus has evolved as part of their behavior. As a matter of fact, I've even seen hooded mergansers add their eggs to the nest which are then brooded by the wood duck hen. Once they hatch, they imprint on Mom Woodie who unwittingly raises them as her own.
On the second day of their lives, the young climb to the nest opening and take a leap of faith, dropping to the ground or water to join their mother who's been plaintively calling to them. When evening comes she'll find them shelter for the night.
The hatchlings need about 7 weeks before learning to fly. During this time they follow Mom in a tight raft and obey her for safety and for finding food. Predation is very high, especially by snapping turtles. Typically, less than half the young will live to make the trip south in the fall. But it's always enough to complete the cycle. We're witnessing that again right now.
