- Wood Duck Box Design
- Wood Duck Box Installation and Height
- Purchasing Wood Duck Nest Boxes and Cone Guards
- Nest Box Material
- Nest Box Placement
- Spacing of Nest Boxes
- Is it too late to put up a box?
- When to clean a box
- Wood duck eggs/dump nests
- Unhatched Wood Duck Eggs
- Young Wood Duck Broods
- Migrating Hens
- Predicting "Jump Day"
- Books on Wood Duck Management
There are many choices for wood duck nest boxes. The WDS recommends boxes made of natural wood. Hens accept them well, and they resist heat build-up the best when measured against those constructed with man-made materials. Wood’s natural insulation properties protect eggs during hot, late season incubations. Cedar lumber is recommended because of its ability to resist rot. A construction design which features a side-opening door, such as the one developed by Don Helmeke, allows walk-up monitoring. See Best Practices
No ladders are needed in this hobby, including during installation of the box. Mount the box on a steel pole or a treated wooden post (never on a tree), with the entrance hole about six feet from the ground. It is very difficult to prevent mammalian predators from eventually accessing a tree-mounted box, and it is easy to accomplish this if the box is mounted on a free-standing, low pole. An effective predator guard installed just beneath the nest box will absolutely prevent access to the box by mammalian predators, egg-eating snakes, and mammalian nest competitors (like squirrels.) A metal, three foot diameter, cone-type guard is strongly recommended and has stood the test of time in many large box units all across the country. The box must be at least nine feet away from a tree trunk and more than eleven feet from an overhanging branch, (see Best Practices). Raccoons and mink eat hens and eggs. Squirrels can and will kill hens that may chance to enter a box where the squirrel has made her nest and is caring for her own litter.
The Minnesota Waterfowl Association (MWA) [www.mnwaterfowl.com] sells cedar WD nest box kits (Helmeke design) with boards already cut to size. The Prairie Pothole Chapter of the MWA sells the same box kits, and also handles sales of the recommended metal cone predator guards through their website [www.prairiepotholeday.com]
In the wild, tree cavities may contain only the rotten wood which lines the cavity and its base. Hens bring no additional material into the cavity, initially using only available rotten wood to cover their eggs. As the clutch develops, they gradually add down feathers from their own breast. We must add bedding to our boxes to help entice the hen to use the nest box. Cedar shavings work well for longevity and protection of the eggs. Such products are available as hamster bedding at most pet shops. As an alternative, cabinet shops often will help out by saving shavings from their planers (of various wood types), then donating them for your project.>
Nest boxes can be installed on land or in water. On land, a shoreline installation is fine, but not necessary. Wood ducks have been known to use tree cavities and nest boxes up to a mile away from water. Land-based boxes can be monitored on a walk-up basis, do not require boats or waders, and eliminate worries about varying water levels and bending of poles from ice-out conditions in the north. In teaching situations, it is safer and easier to bring students nose-to-nose with a clutch of eggs using land-based boxes. In all cases, water or land, an effective predator guard below the box is essential and a cone guard is best (see above.) In the South, snakes can slither up a pole and gain access to the eggs. To deter snakes, make sure the cone guard is sealed tightly against the pole (A square piece of 1/4 inch hardware cloth as a screen next to the pole and under the cone will fill a gap if needed.)
When installing a nest box, the compass directions the box faces is probably the least important consideration and should not be the determining factor. Box usage is more likely to be influenced by a smart installation that accomodates the hens' accessability and flight path to the box. However, we sometimes attempt to do the hen a favor by slightly altering the direction of the nest box opening away from the direction where storm patterns usually develop (locally, northwest and west).
There are no cut-and-dried answers here. In-box cameras demonstrate that wood duck hens will aggressively fight to defend their own nest box when another hen enters. However, they seem to have no problem with other hens nesting nearby. Indeed, multiple nest boxes on a single pole can sometimes be successful. However, we recommend using one box on one pole to prevent the apparent confusion and increased abandonment that have been known to arise with some side-by-side or back-to-back condominium placements. Clustered units, with pole-mounted single boxes spaced as close as 25 feet apart, are generally very successful, but some veteran managers recommend spacing boxes no closer than 50 feet apart. Keep records and see what works best for you.
Facing the nest box opening in a direction to accommodate the hen in her speedy entrance is desirable. However, wood ducks are very agile in flight and can navigate into most cavity/nest box entrances.
The onset of wood duck nesting varies according to where you live in North America. In the Deep South, egg laying can begin as early as late January with many hens having more than one brood during a long season which ends in late summer. In northern states and Canadian provinces, wood ducks return as soon as the ice melt occurs, with egg-laying beginning shortly thereafter. For example, in southern Minnesota small sloughs will often open up toward the end of March, with an initial egg-laying peak in early to mid-April. Wood duck hens in the North will have only one brood per season. If an initial clutch of eggs is destroyed in a natural cavity or unprotected box, they often nest again. By late May to early June, almost all nests have been started. In Minnesota, only a very occasional hatch will occur as late as August.
So, plan to have your box in place before egg laying begins in your locale. But remember that a mid-season placement can attract a late-nesting hen. In northern climates, pole placement on land becomes difficult late in winter when the ground is frozen. On the other hand, overwater placement is much easier when done through the ice, employing an ice chisel and solid footing on thick ice. The best advice is probably that it’snever too late to put up a box. If it’s not used in the current season it will be all set for a pioneering hen in the next one.
Field studies have demonstrated that cleaning a box is advisable as soon as possible after a hatch if you want to obtain an accurate count of the hatch numbers. This also readies the box for a second use in the same season. Many damaging things can happen to the countable egg membranes and egg caps left behind in the box after a hatch. Mice, beetles, secondary songbird nesting, etc. all take a toll. So, cleaning boxes by late summer or fall is recommended. They should also be rechecked for winter damage just before egg-laying begins in the spring.
A mature hen wood duck commonly lays 12-14 eggs. Smaller clutches could be from a young hen or a mature hen renesting after a failed clutch. It is very common for more than one hen to lay eggs in the same nest box or natural cavity. This may result in large numbers of eggs, frequently called dump nests. Such nests are also (more accurately) referred to as compound nests. It’s been shown that compound nesting, on the whole, actually adds to the wood duck population, since a single dominant hen usually prevails and hatches the compound clutch. Hatches of 20 or more ducklings are not unusual in monitored units.
A hen lays one egg per day, routinely in the early morning, and may spend less than 30 minutes in the box while doing so. She then returns to a nearby pond, sometimes accompanied by her drake who had been waiting on top of the box or on a nearby tree limb. When the entire clutch of eggs has been laid, the hen will begin full-time incubation. This assures that all the eggs have a good chance to hatch together on the same day. During the incubation period, the hen will leave the nest box twice daily to feed (morning and evening) for about 30 minutes.
The incubation period for wood ducks varies, but is usually between 28 and 32 days. The entire clutch hatches in less than 24 hours. The hen will leave the nest box with her new brood on the first morning after the initial egg was hatched. After surveying the terrain for predators, she flies down to the ground and begins calling out the brood. The young ducklings are eager to climb up the ladder inside the box and jump from the entrance hole when called. Getting her new brood safely to a pond for food and cover is essential for their survival.
It is very common to find an unhatched egg or two in the nest box after the hen and brood have departed. Perhaps these eggs were infertile or the embryo died prematurely during incubation. They may just be a bit behind in their development, occasionally due to having been laid by a second hen after incubation had begun. Discard the unhatched eggs and clean the nest box for the next hen.
You may occasionally find an entire clutch apparently abandoned in the nest box. If the cold (sometimes discolored) eggs are found to be in an orderly, rosette-type pattern and covered with the blanket of down provided by the hen, it is likely that she was killed while out of the box on her incubation break. She had meant to come back! Other abandoned clutches are in a haphazard pattern without any down cover. If the eggs stay cold and the pattern and number are unchanged over several days, discard the eggs, freshen the shavings, and start over. You have done nothing wrong.
Predators, weather, temperature and food supply will dictate survival rates of the young wood ducks. It varies widely, but it commonly is estimated that only 30-40 percent of the brood will survive the first 90 days. Surviving ducklings will feather out well in about six weeks. Flight feather development may allow juveniles to manage short early flights starting at about nine weeks.
In northern regions, wood ducks are considered to be early fall migrants (late September to mid-October in southern Minnesota.) Woodies travel to southern states and stay throughout the winter. In the spring, when wood duck hens come back to nest, they demonstrate a strong homing instinct. They quite commonly will return to a previously used nest box. In large, ongoing banding studies in California, two remarkable hens have returned to the same box, or one of two adjacent boxes, for nine years in a row. Hens generally choose a different mate each year. The drake then follows his hen to her nesting site during the spring migration. Consequently, the drake’s destination may vary greatly from year to year. The oldest wood duck recorded from a USFWS band return was 23 years old.
In southern states, a separate population of wood ducks do not migrate at all, thus earning their alternate name in some parts of the South: Summer Duck.
A hen wood duck usually lays one egg per day until her clutch is complete. The normal incubation period for a wood duck is usually 29 -30 days. You will have to get an accurate egg count and note the date sometime during the egg laying stage, before the hen starts her incubation. For instance, if you checked a vacated nest box some afternoon and found five eggs, and the date was April 10th, mark your calendar on the 10th with five eggs.In a few weeks, when the hen is incubating, you will need another egg count. Watch for the hen to leave for her morning or evening feeding, then re-check the nest box and get a total egg count. If the total egg count was twelve eggs, and knowing that during the egg laying process a hen usually lays one egg per day, add seven days [for the seven additional eggs] to the calendar you previously marked on April 10th. Using the new date of April 17th, you can add 30 days [incubation time] for the estimated hatch – which would be May 17th.
Now, due to the fact that wood duck hens will occasionally 'miss’ laying an egg on any given day during the egg laying process, the hatch date is just an estimate, but it will get you close. Near the hatch date, monitor the nest box more closely and re-check it when the hen leaves for her evening feed. On a day when you find some of the ducklings hatched- you will know that the entire brood will leave the following morning. At this point, avoid further contact with the ducklings or the hen. The hen and her brood will usually jump between 7:00 AM and 9:00 AM that following day, but the 'jump' can extend anytime up to noon –especially, if the hen feels threatened from predators or if the weather is inclement.
The standard reference for management of wood ducks remains the 588 page
textbook written by Frank Bellrose and Daniel Holm, entitled: 'Ecology and
Management of the Wood Duck'. It is a Wildlife Management Institute book, and
was published by Stackpole Books in 1994.
Their website address is:www.wildlifemanagementinstitue.org
I know of no serious wood duck hobbyist or professional manager who does not use this great resource to the fullest extent. My understanding is that it is no longer in print. You should exhaust every means in order to obtain a copy.