Homes For Wood Ducks
What can I do to help wildlife? Each year the Massachusetts Division of Fisheries and Wildlife receives inquiries from individuals and groups looking for projects that will benefit wildlife. There are many ways to get involved constructively and one way is by building nest boxes for use by wood ducks or hooded mergansers. Under natural conditions wood ducks and mergansers build their nests in holes or rotted hollows they find in old or damaged trees.
Not every cavity in an old tree is suitable for a nest site. Cavities must be deep and roomy because the ducks cannot enlarge them, and they must contain some soft material for covering eggs since the ducks do not carry in material like most other birds. The nest tree must also be near water, for although wood ducks have been seen searching for nest sites a mile from the nearest body of water, the ducklings must make a perilous journey from such a nest to the water, and the survival rate declines with the distance the young must travel. Many natural nest sites are drilled by woodpeckers but only those made by pileated woodpeckers are large enough for ducks to use. One study conducted in Ontario reported a notable rise in wood ducks following an increase in the surrounding populations of beaver and pileated woodpeckers. Unfortunately, many cavities are not empty. Often wood ducks find that suitable cavities are already in use by squirrels, owls, honey bees, and other forms of wildlife.
Fortunately, the wood duck will accept "artificial housing" provided it meets certain basic requirements of size and safety. Unlike most ground nesting waterfowl, the wood duck does not defend a large territory around its nesting site. This allows "woodies" to nest closely together, and where boxes are provided and maintained, a flourishing colony can build up. Be sure to use rough-cut pine boards for your wood duck box--the rough face of the board allows the newly hatched ducklings to gain a foothold as they climb out of the box for their first swim!
Unfortunately, the colony cannot truly start from scratch. Female wood ducks return year after year to their natal areas. In late summer, some females, usually juveniles, explore new areas to which they will return the following spring. Thus a population may be supported and expanded, but his will only succeed in areas that have an initial population that can overflow into the new area.
Areas that do not have resident ducks may come to support them if there is an overflow from a neighboring population. Because of the almost universal scarcity of natural nesting sites and because of intense competition from other wildlife, nest boxes are often used within a short time of placement. Occasionally people erect boxes in areas that look as though they should have wood ducks or where they have seen wood ducks in spring or fall. These ventures are almost all disappointing because of the wood duck's homing tendency.
In general, the Division recommends setting out only a few boxes (3-5) on an area near an existing wood duck population. When half or more of the boxes are used, additional boxes should be provided for the increase that will come when the young return to their natal area to rear their own young.
In theory it would seem as though the erection of nest boxes would solve all the problems of wood ducks, but artificial cavities are not a panacea and may, in fact, do more harm than good unless they are set up in suitable locations with protection against predators, and are maintained in good condition.
When wood ducks are concentrated in nesting boxes predation becomes an increasing problem. Raccoons are common in Massachusetts and account for most of the predation losses. Other predators include squirrels, and later on, snapping turtles. Raccoons frequent swamps and other wet areas in search of food. Once a raccoon has robbed a wood duck nest it will check any and every similar box in the area. If the opening is too small, the raccoon will gnaw at the opening to enlarge it. Because the raccoon is agile and learns quickly, it is one of the most serious dangers to wood ducks. Nesting boxes may become death traps and one raccoon can wipe out an entire colony of birds. They would be safer dispersed in the wild.
To counter such losses the Division of Fisheries and Wildlife has developed a tunnel predator guard which prevents the raccoon from enlarging the hole or reaching in for eggs. The guard is a simple wooden tube with inside dimensions of 4 inches x 4 inches which is nailed over the entrance hole so that is projects out 9 inches from the front of the box. As a further deterrent the Division recommends that boxes be placed on wooden poles, sign posts, or angle iron driven into the mud where they will be surrounded by water. This is best done in the wintertime by cutting a hole in the ice at the desired location and placing the pole before the box is put up. Placement in the water is especially convenient for the ducklings because they will not have to travel overland to reach water and cover after they hatch. An extra bit of protection may be added by wrapping the post with 18 inches or more of aluminum flashing to discourage climbing creatures, especially mink, which cannot be kept out of boxes by the tunnel guards.
A suitable area for a nest box is relatively quiet and undisturbed. It must have plenty of water and emergent vegetation to provide accessible cover where the young can find safety from predators or disturbances. There should be tussocks or dry nesting places where female can brood the ducklings at night. There must also be an abundance of insects to provide the ducklings with the high protein diet they need for their first six weeks.
In choosing a site for a nest box it is important to remember that the wood duck operates instinctively, not consciously. She will accept any suitable location. However, an area that is safe and quite in April may be heavily used by motorboats and waterskiers in June when the ducklings are ready to leave the box. Poorly located boxes can lure females into nesting areas where their young have little or no chance of survival.
Finally, a wood duck that nests successfully in a nesting box will do so again and again. Thus it is imperative that the boxes be maintained in good shape so that birds that have become dependent on the boxes will not, a few years hence, be forced out when the boxes become fouled or fall into disrepair. If you want to try your hand at helping the wood ducks, use the wood duck box diagrams and follow the specific recommendations on box construction and placement. This information will enable you to build and erect boxes successfully and with real benefit to this most beautiful and fascinating bird.
If you have any questions or problems with wood duck boxes, contact your closest Division of Fisheries and Wildlife District office. Our skilled staff will be happy to assist you. When you do set out nesting boxes, please notify that office of the number and location-our biologists would like to know. They may be able to suggest improvements and help monitor nesting success. We are glad to take the opportunity to help you. Together we can help restore homes for Massachusetts' cavity nesters.