The wood duck is Mississippi’s stateduck (Fig. I). This denizen of theswamps lives year around in theMagnolia State. However, Mississippi’sforested wetlands also provide impor-tant habitats for wood ducks whichmigrate to escape winter at northernlatitudes and to feast on acorns andinvertebrates in our state’s hardwoodbottomlands.

Besides being one of the most beautifulducks in North America, wood ducksalso are important game birds. They areusually first or second in the harvest ofall ducks in the Mississippi and AtlanticFlyways, which is the primary range ofthe wood duck on this continent.Indeed, wood ducks contribute signifi-cantly to the economy derived fromwaterfowl hunting in Mississippi andthese two flyways.

Wood ducks are cavity nesting ducks,meaning they nest in holes of trees(created by woodpeckers and/or bynatural decay after limb breakage) andartificial boxes constructed and main-

tained by wildlife managers. Nest boxes,which are usually made of wood, havebeen used widely for over 60 years toestablish and increase wood duck popu-lations throughout the United Statesand Canada. It is believed that nestboxes are especially important forwood duck production in Mississippiand other southeastern states becausesuitable natural cavities are scarce.

Due in part to the scarcity of naturalcavities and nest boxes in many areas,several hens may lay their eggs in a sin-gle cavity or box, resulting in “dumpnests." These are aggregations of eggslarger than the normal clutch size ofabout I5 eggs. Wildlife scientists in theForest and Wildlife Research Center atMississippi State University have foundover 75 eggs in a nest box.Extraordinary numbers of eggs in nestboxes can decrease wood duck produc-tivity, because hens cannot effectivelyincubate and hatch such large clutches.

Therefore. the scientists reasoned thata smaller nest box, which wouldn’t

Fig. 2. New nest box (left) and Con-ventional large box. Dimensionsventional large box. Dimensions

each are in incheach are in inch

accommodate asaccommodate asmany eggs, mightmany eggs, mightbe a partial solu-be a partial solu-tion to any negativeeffects of dumpnesting. The scien-tists designed anew nest boxapproximately half the size of conven-duck boxes (Fig. 2). The design was based on thesize of box needed to accommodate an incubatinghen and a normal size clutch atop 3-4 inches ofwood shavings as nest material. The scientists pre-dicted that the new design would decrease num-bers of eggs laid in the small box, and perhapsimprove hatching success and decrease numbers ofunhatched eggs left behind.

The scientists placed equal numbers of the conven-tional large and the new small nest boxes in wet-lands at Noxubee and Yazoo National WildlifeRefuges (Mississippi) and compared wood duck useand production between the two types of boxes inI994 and 1995. One box of either type was ran-domly assigned and attached to a 4 x 4 inch, treat-ed wooden post equipped with a galvanized circularpredator shield 30 inches in diameter (Fig. 3).

Significant results from the study are summarized inTable I . The researchers found: I. more large thansmall boxes were used by nesting hens, 2. moreeggs were laid in large than small boxes, 3. moreducklings exited large than small boxes, and 4. moredump nestsoccurred in largeboxes. However,nesting successdid not differbetween largeand small boxes.Importantly,ducklings were

produced moreeconomically fromsmall than largeboxes becausesmall structureswere less expensiveto construct. Thescientists concluded

that the small nest box offers wildlife managers analternative structure, which I provides a suitablenesting environment for wood ducks or hoodedmergansers, 2. is more cost-effective for ducklingproduction than the large box, and 3. is easier toinstall because of its light weight.

Nest boxes should be constructed of weather-resis-tant lumber (e.g., cypress, tupelo, cedar) to enhancelongevity of the box and benefit: cost ratios. Rough-cut pine can be used and its life increased by treat-ing the exterior of the box with a clear woodpreservative; however, painting boxes is not recom-mended because wood ducks may prefer a naturalexterior that blends with tree bark. If rough-cutlumber is used to construct boxes, it is not neces-sary to attach a “screen ladder” to the interior ofboxes to facilitate the ducklings’ exit. With long,clinging toenails, ducklings can easily scale the insidewall of boxes toward the exit hole without the aidof a ladder. However, it may be advisable to roughenthe interior wood surface of the box from the bot-tom of the box to the hole with a file or knife togive the ducklings a “toe-hold” during their exodus.

Dry-wall screws function better thannails to hold sides of boxes togetheramid Mississippi’s variable climate. Theroof of boxes should be hinged to thetop rear to enable entry by managersfor the purposes of cleaning and main-tenance, as well as monitoring woodduck use and production. Additionally,the roof can be locked to either side ofthe box with a screen door eye-hook.

Fig. 3. Wood duck boxport with predator shield

For people trying to increase benefit: cost ratiosthey may consider attaching two small boxes, frontand back, to the 4 x 4-inch posts, but one box perpost is probably best. Boxes should never beattached to posts without a predator shield; the lat-ter should be attached tightly to the post a mini-mum of 2-3 feet below the bottom of nest boxes toprevent snakes and other predators from stretchingacross the gap between the post and the shield andthereby gaining access to the nest. Boxes attachedto trees also should have some type of predatorexclusion device, such as aluminum flashing materialat least 2-3 feet in width wrapped around the treebelow the box. Height of box above ground doesnot seem critical to use by nesting wood ducks.More importantly, however, boxes should be placedat heights to enable efficient and effective mainte-nance and box checks by managers, and both boxesand predator shields should be placed above maxi-mum high water level to prevent inundation ofboxes during floods and access by predators, such asraccoons and snakes. Interestingly, the scientists alsohave experienced beavers swimming to partially sub-mersed nest boxes and these animals gnawing onthe boxes and the posts despite the latter beingchemically treated.

Box clean-outs and mainte-nance of boxes should beperformed at least annually,but no later than early-midwinter because wood ducksbegin nesting as early as lateJanuary in southern UnitedStates. If data on woodduck production aredesired, it is preferable to

check boxes soon after each nest is completed andbefore evidence of successful nesting (i.e., egg shellmembranes) deteriorates or disappears. The scien-tists prefer to remove unhatched eggs and downyfeathers after each nesting attempt to increase sub-sequent use by nesting ducks or other birds (e.g.,flycatchers, blue birds, kestrels).

Although the nest-box study was not intended toexamine wood duck duckling survival after depar-ture of the hen and brood from nest boxes (Fig. 4).research is underway by the scientists to estimatesurvival of brood hens and ducklings, both markedwith radiotransmitters. The goal of this research isto identify habitats where nest boxes should beplaced to maximize survival of the hen and herbrood after hatching. Although this study will not becompleted until the year 2000, a preliminary recom-mendation is to scatter boxes amidst trees orshrubs (e.g., bottomland hardwoods, cypress, tupelo,willows, buttonbush) standing in water, so ducklingscan easily swim away with the hen after their exo-dus from the box. Boxes should be placed awayfrom limbs of trees/shrubs to prevent predatorsfrom using the vegetation to access the boxes(Fig. 5) and overhanging vegetation that grows near

boxes should be removed periodically.Boxes should never be placed on dryland; predators, such as bobcats, canjump on a box and capture a nestinghen. Finally, largemouth bass and otherfish prey on ducklings, so combining basspond and wood duck management maynot be a good idea. Indeed, fish may foul

your waterfowl plan!

fg 4 Wood duck ducklings exiting a nest box

Scientists Contributing to thisResearch Advance

Dr. Richard M. KaminskiDr. Bruce D. Leopold

Graduate Research AssistantsJ. Brian Davis

Scott E. Stephens

For moreinformation contact:

John E. Gunter. DirectorForest & WildlifeResearch Center

Box 9680Mississippi State. MS 39762

601-325-2952Fax: 601-325-8726

jgunter@cfr.msstate.eduhttp://www.cfi:msstate.edu

Sponsors of the wood duck researchreferenced herein include Anderson-Tully Company, the Delta WaterfowlFoundation through the DeltaWaterfowl and Wetlands ResearchStation, Ducks Unlimited’s Institute forWetland and Waterfowl Research,Federal Aid in Wildlife Restorationthrough the Mississippi Department

of Wildlife, Fisheries and Parks, theForest and Wildlife Research Center(Mississippi State University), the U.S.Army Corps of Engineers, the U.S. Fishand Wildlife Service, the U.S.Geological Survey (BiologicalResources Division), and the WelderWildlife Foundation. Wood duck pho-tos by David McEwen, Starkville, MS.

Suggested Reading

Bellrose, F.C., and D.J. Helm. 1994. Ecology and management of the wood duck. StackpoleBooks, Mechanicsburg, Penn. 588pp.

Stephens, S.E. 1995. Effect of reduced nest-box size on wood duck production. M.S.Thesis,Mississippi State Univ., Mississippi State. Ms. 45pp.

__, R. M. Kaminski. B.D. Leopold, and PD. Gerard. 1998. Wood duck reproduction inlarge and small nest boxes. Wildl. Soc. Bull. In press.