One way to improve an area's value as wildlife habitat is to add nest boxes for wood ducks. Wood ducks normally nest in tree cavities near lakes, rivers, ponds, and other wetland areas. Often, nest cavities are in short supply, limiting the size of wood duck populations. Fortunately, "woodies"- readily accept manmade nest boxes. Providing nest boxes for wood ducks can be fun and rewarding and, if done properly, can establish or increase local populations of this beautiful bird.
Learning about the behavior and requirements of breeding wood ducks can help you attract wood ducks to nest boxes. This information also can help you better understand the comings and goings of wood ducks at a nest, if you are lucky enough to watch (from a distance).
Most duck species migrate to northern breeding areas to nest and raise young. Wood ducks, however, breed throughout the eastern United States and are abundant in the Southeast. In Florida, wood ducks enjoy a long nesting season, from late January into August. Most nesting occurs February through June. When a wood duck female (or hen) is ready to start a nest, she and her mate begin searching for a suitable nest site and may inspect several cavities before choosing one. Once the hen settles on a nest site, she usually will lay one egg each day until the clutch is complete, an average of 12 eggs in a normal nest. While she is laying eggs, the female visits the nest just long enough to lay the egg. Woodies do not bring nesting material to the nest. During this egg-laying stage, the hen hides her eggs by burying them under decayed wood and other debris in tree cavities. In a nest box, a thick layer of wood shavings serves this purpose. When laying the last few eggs, the female adds downy feathers from her breast to the nest.
Hen wood ducks usually begin incubating after all of the eggs are laid. Incubation lasts about 28-30 days. So, when adding the egg-laying period to the incubation period, the entire nesting period typically lasts 40-42 days. The male wood duck usually leaves the female after incubation begins. When incubating, the hen usually takes two breaks each day to feed, typically in the early morning and late afternoon.
After hatching, ducklings stay in the box (or cavity) for only 12-24 hours. When the ducklings are ready to leave the nest, the hen calls them out with a soft "kuh, kuh, kuh." The ducklings climb up to the entrance hole and jump to the ground or water below. The hen then leads her brood to areas with shallow water, ample aquatic vegetation, and abundant insects or other inverte-brate foods. The specific type of vegetation is not as important as the abundance and density. Brood rearing areas should have taller emergent vegetation (grassy, herbaceous, or shrubby plants extending above the water surface) so that the ducklings can be hidden within and under it, out of view from hawks and owls. Thick submerged vegetation usually harbors abundant inverte-brates for duckling food. Ducklings also find invertebrates at the water's edge, on the surface of floating-leaved vegetation (e.g., water Jiffies), and among almost all aquatic vegetation. In general, good brood-rearing habitat provides high-protein foods near escape cover. Ducklings feed themselves from the time they leave the nest.We normally expect about half of the ducklings to survive until they are able to fly at 8-10 weeks. The hen generally stays with the ducklings for 4-6 weeks.
Wood duck nests sometimes fail to hatch because either predators destroy the nest, the eggs were infertile, the hen abandons the nest, or for other reasons. When a first nest fails, the hen often attempts a second nest. In Florida, a small proportion (7-10%) of wood duck females will hatch and raise two broods during the nesting season. Wood ducks are the only species of North American duck known to regularly accomplish this reproductive feat in a single nesting season. This behavior is more common among wood ducks at southern latitudes, where nesting seasons are longer.
Even in pristine conditions, suitable natural nesting cavities for wood ducks usually are in short supply. Certain behaviors help woodies overcome this fact, and the long-term success of a nest box program depends on understanding these behaviors.
Female wood ducks nearly always return to nest near the site where they were hatched and will nest in this area year after year. Therefore, as a population builds, so will the demand for nest sites. Wood duck females also will lay eggs in nests incu-bated by other females. This behavior is called nest parasitism or "dump nesting." Dump nests can have as many as 40-50 eggs, and nests with 20 eggs are common. Biologists believe that dump nesting is one way wood ducks make up for a general shortage of nest cavities; that is, a female unable to find a cavity would be better off to dump eggs in another bird's nest rather than not nest at all. A small to moderate amount of dump nesting can add to the duckling production in an area. However, when dump nesting becomes excessive, dumping females can interfere with incuba-tion, resulting in nest abandonment or lowered hatching rates. Nest boxes that are placed close together and are highly visible seem to cause a rapid increase in dump nesting, eventually leading to severe nesting interference and a decline in production.
Types of Boxes
You can buy wood duck nest boxes in several designs and materials. Wood construction is the most common, but boxes also are available in sheet metal, fiberboard, plastic, and cardboard. Generally, the types commercially available have been tested and will work.
Each type has advantages and disadvantages. Wooden boxes are generally considered the most attractive and blend in well with the natural environment. Wood ducks seem to accept wooden boxes faster than other types. Over the years, however, you will spend more time repairing and maintaining wooden boxes than either metal or plastic boxes. Also, making wooden boxes requires the harvest of large trees, often cypress trees, which might be better left standing to provide natural habitat for wood ducks and other wildlife. Metal boxes are lightweight and durable but do not blend in well in the woods. Also, when placed in full sun, metal nest boxes may become so warm that eggs will not hatch. However, metal boxes placed in full or partial shade stay adequately cool. Wood ducks will readily nest in metal boxes, but not as quickly as in wooden boxes. Plastic boxes also are durable and lightweight, but you should avoid boxes made of dark colored plastic. In the South, these dark boxes become dangerously hot, putting eggs and females at risk. The newer, commercially-made, plastic boxes are light in color to reduce this problem.
Regardless of which type you consider, you should check several important characteristics. Inside dimensions should be approximately 10x10 inches or at least a 10-inch diameter. The entrance hole should be approximately 3x4 inches and oval. There should be some type of duckling ladder inside the box, such as a strip of hardware cloth, for the ducklings to climb to reach the entrance hole. The box should have drainage holes and some way to open the box to clean out old nesting material.
How to Build a Box
Many people choose to build their own wooden nest boxes. We recommend using rough-sawn (unplaned), cypress or cedar boards, 1x12 inches. One box requires 10 feet of board. The wood should not be painted, stained, or chemically preserved. Inside dimensions should be appreoximately 10x10 inches, and the entrance hoel should be a 3x4-inch oval. Securely attach a duckling ladder of plastic gutter-guard mesh ar 1/4-inch hardware cloth below the entrance hole on the inside. Drill drain holes in the bottom. Use rust-resistant hardware, and provide a door or lid that allow you to clean out the box. A sloping roof may reduce splitting and rotting of this piece of wood. Download building instructions: How to Build a Wood Duck Box .
Whether you make or buy nest boxes, you will need to add nesting material, because wood ducks normally do not bring material to the nest. We recommend wood shavings, 4-6 inches deep in the bottom of the box. Shavings should be from untreated wood. Cabinet makers or shops that make wood moldings are good sources for wood shavings. Shavings work better than sawdust alone, because sawdust tends to hold moisture.
Nest boxes can be mounted in several ways. For the best nest success, boxes should be placed on posts or pipes equipped with predator guards. We do not recommend mounting boxes on tree trunks because it becomes nearly impossible to deter nest predators from these boxes. If the box is mounted to the post with a single bolt through the back, you can easily turn the box upside down by pivoting it on the bolt. This allows you to dump the contents when the box needs to be cleaned.
The most common predators of wood duck nests in Florida are gray rat snakes and raccoons. The 3x4-inch oval entrance hole will exclude racoons larger than 10 pounds. Further protection from racoons and snakes can be achieved by adding a flat or conical metal shield below the box, extending at least 18 inches from the post in all directions. Make sure the guard meets flush with the post, because snakes can squeeze through very small gaps.
Where and how to Place Boxes
Your best chances of success will be with boxes placed in wetlands where you commonly see wood ducks, suggesting that the area provides adequate wood duck habitat, including cover and a food supply. Place boxes so that the entrance hole faces an opening in the lake, pond, or marsh. This orientation helps birds notice the entrance more easily and may entice wood ducks to use your box sooner. Place the boxes about 6 to 10 feet above the ground or water surface. If the water level fluctuates, the predator guard should remain about 3 feet above the high water level. We recommend placing boxes in the shade as much as possible. To maximize predator protection and duckling survival, boxes placed over the water are best. Woodies will readily nest in boxes on land, but risk of exposing the nest to predators is higher, and ducklings are especially vulnerable when they have to cross land to get to water. Boxes also should be placed near good brood-rearing habitat, so that the brood does not have to travel far before reaching feeding areas with protective cover. Finally, keep in mind that you will need to maintain the boxes annually, so place them where they are convenient for you to reach, with a ladder, tools, wood shavings, etc.
A common question is, "How many boxes should I place on my pond or lake?" The first consideration is how many boxes you will be able to maintain year after year. Second, to reduce adverse effects of interference from severe dump nesting, boxes should not be placed too near one another. We recommend that boxes be at least 100 yards apart and visually isolated so that you cannot see one box from another. We suggest starting with only a few boxes and then adding more as your budget, time, and habitat allow. You may want to wait and see if the first boxes are used by woollies before investing in more.
Once you put up a box, you accept responsibility to main-tain it annually. Examine boxes in December or early January to make sure they are in good repair and ready for the upcoming nesting season. Remove any remains of last year's nests, includ¬ing unhatched eggs, larger egg fragments, and down feathers. Occasionally, you may need to dump everything inside the box and replace the nesting material, particularly when it becomes badly matted, soiled, or infested with fire ants or other insects. Make sure the box has at least 4-6 inches of suitable nesting material. Beware of and eradicate wasps, which find wood duck boxes attractive places to nest. Avoid applying wasp spray or other contaminating chemicals inside the box, especially on the nesting material.
Boxes occasionally need repair or replacement of split lids, loose hinges, latches, or pulled nails. Make sure the hardware-cloth ladder on the inside of the box is in place and has no protruding wires. Check the predator guard for any needed repairs.
Several other wildlife species find wood duck boxes good places to nest or roost. These species include gray and flying squirrels, bats, screech owls, great crested flycatchers, Carolina wrens, Carolina chickadees, eastern bluebirds, flickers, and tree frogs. You may see evidence of these animals when you maintain your boxes.
Final Thoughts and Recommendations
If you decide to add wood duck nest boxes to your property, be prepared to be patient. It often takes a few years before wood ducks find and accept artificial nest sites, even in areas where you commonly see wood ducks. Once the birds do begin to use your boxes, use likely will increase quickly. Remember that after a hen successfully nests in a box, she usually will return to the same box or group of boxes to nest the next year, and so will any female offspring she produces.
After considering economics, aesthetics, biology, predators, ease of maintenance, and local conditions, we recommend the following approach for starting a wood duck nest box project in Florida:
Use wooden boxes, on 4x4-inch, pressure-treated, wooden posts, with conical, sheet metal predator guards. Place boxes in the shade, out in water averaging about 2 feet deep, in a pond or wetland that has good brood-rearing habitat. Boxes should be visually isolated from each other. Maintain the boxes annually, around the first of the year.
Keeping and maintaining a wood duck nest box is an easy way to provide this colorful species with one of its requirements that may be in short supply. You could be rewarded with the enjoyment of watching ducks make use of the habitat feature you provided. Good luck!
Although adding nest boxes can increase wood duck populations on a local scale, most of Florida's breeding wood ducks nest in natural cavities. To be large enough for nesting wood ducks, these cavities must occur in fairly large, old trees. Therefore, the welfare of Florida's resident wood duck population depends on conserving and managing mature forest stands in conjunction with healthy and productive wetland habitats.