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MISC0142

WoodlandFish and Wildlife

The Northwest has sev-eral ducks that utilize cavitities or holes in

trees for nesting. These include the wood duck (Aix sponsa), hooded merganser (Lophodytes cucullatus), common merganser (Mergus merganser), common goldeneye (Bucephala clangula), Barrow’s goldeneye (Bucephala islandica), and the bufflehead (Bucephala albeola). Throughout the Pacific Northwest (Oregon and Washington), the wood duck is the most common and widespread cavity nester during the nesting season. In Oregon, the other species usually nest in the higher ele-vations of the Cascade Moun-tains where small woodland operations are not common. As one progresses to the north, nesting of these species will occur in lower elevations of the Cascades, and in river val-leys and lakes of northeastern Washington. An exception is the hooded merganser. This species frequently nests in low elevation areas in conjunction with wood ducks. Nonetheless, the most common cavity nest-ing duck associated with small woodland owners’ operations is the wood duck. Because

of this disparity in nesting habitats and distribution, this publication will deal primarily with the wood duck, with ref-erences to other cavity-nesting ducks as appropriate.

Some people say the wood duck (or “woodie”) drake is the most spectacularly marked duck in the world, or at least in North America, with the hooded merganser (or “hoodie”) being a close second. Regard-less, the male woodie is one of nature’s masterpieces. In flight, these birds are unusual in appearance with their crested heads, square tails, and broad wings. But close up

or in the hand, the drakes are difficult to adequately describe in words.

The head crest of the male wood duck has iridescent green in front blending to purplish at the rear. Red eyelids and irises are set in purple to green feath-ers that cover the face. The bill is small but colorful, with white edges, a red base and sides, and a black tip and ridge. Along the bird’s flanks, bronze feath-ers have fine black striping and some are black tipped. The dark back and rump are bordered by white stripes. White also accents the crest and collars the throat area.

Cavity Nesting Ducks

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In contrast, the female is more drab, but has a distinctive crest and white rings around her eyes. Overall, she is brown-ish with a touch of iridescent green and the under part of the tail and belly are white.

Both sexes are about 20 inches long and weigh about 1 1/2 pounds, making them smaller than a mallard (about one-half the size) but larger than a teal. The hooded mer-ganser, common goldeneye, and bufflehead are about the same size as a wood duck, whereas the Barrow’s goldeneye and common merganser are larger—closer in size to a mallard.

The bill of the wood duck is very narrow and elongated—more like a beak than a bill. The bill of both tree-nesting mergansers are more narrow, yet with a serrated edge—much like a knife blade for the pur-pose of catching and holding fish and other aquatic verte-brates. It is possible to confuse both sexes of the hooded mer-ganser with their wood duck counterparts, especially at a distance. However, the color-ation pattern of the drakes are substantially different, with the much larger crest or hood of the drake hoodie colored white with a black border, much cin-namon or buff, and white on the body. The crest of the female is much larger and pronounced than that of the wood duck hen.

Vocalizations are quite differ-ent, as well. The wood duck is very distinct. The female makes a squealing “weeeek weeeek” sound unlike the quack or other vocalizations of other ducks. The male makes a similar sound, but very softly and seldom.

For a description of the other cavity nesting ducks, refer to any number of good birding books and manuals commonly found in book stores and librar-ies or online.

As with most ducks, cav-ity nesting ducks molt twice a year. During the adult molt that begins in July and lasts until mid-September or October, the drakes look much like the hens. For a time during this period, both sexes are flightless while their flight feathers are molted and replaced.

In the early 1900s, over-hunting and habitat destruc-tion had decreased wood duck populations to the point where there was fear for the continued existence of the species. Restric-tive laws brought the birds back until, in the 1940s, hunters were again allowed to take them during the season. Hooded merganser numbers suffered greatly during the middle of the last century, probably due to loss of nesting habitat (snags) along water courses. Since then, the popular and effective pro-gram to provide artificial nest boxes has increased numbers of both species and greatly increased the distribution of the wood duck, as well. Wet-land drainage is still a serious

problem for ducks in some areas. Protection of riparian and wetland areas is important in retaining wood duck habitat.

Wood duck numbers are comprised of a large eastern United States population and a relatively small western popu-lation. The greatest number of woodies are found in the southeastern United States with their range extending north into Canada and west to Texas and the eastern edge of the Great Plains. The greatest numbers in the west are found in British Columbia, western Washington, the Willamette Valley of Oregon, and especially the central valley of California. However, the birds are found in fewer numbers in most areas in Oregon and Wash-ington where there is a suitable habitat. They are fairly common in northeastern Washington. Wood ducks both nest and win-ter in the western part of Oregon and Washington, but most of the Pacific population migrates to California for the cold months. The distribution of the hooded merganser is similar to that of wood ducks.

Summer populations of the other cavity nesters are primar-ily found east of the Cascades along major river corridors, lakes, and large reservoirs where substantial older forests occur. Their summer numbers are low, giving them “rare sum-mer inhabitants” status in the Pacific Northwest. In winter, however, they are extremely common in coastal estuaries, bays, rivers, and freshwater environments of the lowlands of western Oregon and Wash-ington. Good-sized populations of goldeneyes and common

Distribution

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mergansers are also found on large bodies of water and rivers east of the Cascades crest dur-ing winter, as well.

As the name suggests, wood ducks are residents of wooded areas near water. Unlike most of their relatives, woodies often roost in trees and nest in cavities in trees. They are seldom seen in large flocks like many other ducks, but are more often seen in pairs or groups up to about six. During the breed-ing season, the males do not establish large territories as is the case with most other ducks, but they do defend the area immediately around the female.

Nesting usually starts in late March and an aver-age clutch is about 12 eggs. A fairly common occurrence is the “dump nest.” These nests are used by a number of hens (including other cavity nesting ducks—the hooded merganser, in particular) and may contain up to 40 eggs. Eventually, one female may sit on the nest with

varying hatching success. Incu-bation period is about 30 days. Only the females incubate and eventually rear the young.

When they are about one day old, the young wood ducks climb up the inside of the nest, perch momentarily on the edge of the entry hole, and then launch themselves into the air. With tiny, fuzzy wings flapping to no avail, they may fall as far as 50 feet to the ground, but are so light they are seldom injured. The calling mother assembles the group and leads them in a pack to the nearest water. If they are hatched too far from the water, many will not make it. On average, only about half of the hatchlings will survive to adulthood. They have, however, been found nest-ing success-fully more than 1/4 mile from water.

As is true with many young birds, the young wood ducks are dependent on a sup-ply of insects and other inverte-brates for the early part of their life. Until the youngsters are about six weeks of age, animal foods such as mayfly and drag-onfly nymphs and other aquatic insects make up about 85% of their diet. As the birds mature, they turn to a variety of plant materials found in and around

LiFe History

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wetlands or other aquatic envi-ronments and a few kinds of terrestrial vegetation.

Adult wood ducks con-sume the larger seeds and fruits of native trees, shrubs, and emergent aquatic plants found growing adjacent and in aquatic habitats. They also pick up waste and spilled corn and other agricultural grains near the aquatic areas where they are living. This is especially true during the fall migration and within wintering areas. When available, acorns of many oak species are relished by wood ducks, as are filberts or hazelnuts, occasionally—especially from commercial orchards.

Young of the other cavity nesting ducks consume a diet similar to the young wood ducks: almost exclusively, a diet of high protein, minerals, and energy-rich invertebrates and small vertebrates. Unlike adult wood ducks, the other cavity-nesting adult ducks rely on a diet of both invertebrate and vertebrate aquatic ani-mals (mergansers rely almost exclusively on small fish) and some submerged aquatic plant materials.

Almost any body of water has potential to provide a home for a pair of nesting wood ducks. Natural nests sites are hollowed out cavities up to 50 feet above the ground in trees within a 1/2 mile of water (or actually standing in the water). Cavities excavated by pileated woodpeckers are commonly

used and more nests occur in deciduous trees, especially cot-tonwoods, than in conifers.

Cavities in trees located within or immediately adja-cent to aquatic environments are more frequently used by the other cavity nesting ducks. The best cavities are located within mature forests, along major river and stream systems and reservoirs in the Cascade Mountains and northeastern Washington. Occasionally, these ducks have been found to nest in cavities in talus slopes and rocky outcroppings. As stated previously, wetland drainage and especially the removal of snags that may contain suit-able nesting cavities have been responsible for the decline of wood ducks and hooded mer-gansers in many areas.

Fortunately, wood ducks and, to a lesser extent, the other cavity nesting ducks have proven to be very adaptable to use of artificial nesting sites. A small wetland or creek with an adequate riparian area can pro-

vide the roosting, nesting, hid-ing, and feeding areas needed for a pair of woodies to “set up housekeeping.” Wetlands (espe-cially shrub- or tree-dominated sites), oxbow ponds, or other “still” water with substantial emergent vegetation and woody structure is essential for brood rearing. Wood ducks truly like their habitats “messy,” meaning that ideal habitat includes sub-stantial dead trees, logs, stumps, and associated wetland plants all found along and within their aquatic homes. Similar condi-tions (but without so much near shore “messiness”) may be pres-ent on larger bodies of waters in eastern Washington and Ore-gon, such as major rivers, lakes, and reservoirs, that contain both substantial aquatic invertebrates and vertebrates. These are espe-cially attractive as nest sites or summer habitats for other cav-ity nesting ducks common to the area. If trees or snags with suitable cavities are not present, an artificial nest can be installed to provide their home.

Habitat

10”Front

10” Side

8”

10”12”

Oregon Department of Fish and Wildlife

4”

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There are a number of con-siderations when putting in artificial nest boxes. Plans for the construction and placement of the boxes are available from your wildlife agency or other sources listed in the references. The natural nest cavity or nest box should be at least 12 inches deep and 10 inches wide. The entry hole should be 3 to 4 inches in diameter. In artificial boxes, an oval hole 3 inches high and 4 inches wide tends to discourage entry by raccoons (see Predators). The minimum 12-inch depth will also keep rac-coons from reaching down to the nest. The box should always be vertical or lean slightly to the front so the young ducks can climb out. Rough lumber should be used for the front or screen attached on the inside to be used as a ladder. Also, the bottom of the box should have a few inches of sawdust or shav-ings in it for nesting purposes. The most successful boxes are usually within 200 yards of water and located above the high water levels associated with flooding events. Boxes should be at least 30 feet apart from each other, or visually iso-lated. Do not paint the boxes as some paints contain ingredients potentially toxic to ducks.

It is not difficult to build and install boxes, but certain guidelines must be followed to increase success. Improperly built and installed boxes can be detrimental to the ducks, rather than beneficial. Nest boxes must be checked and cleaned each year to be most productive. The hens will often return to the same box year after year, if it is main-

tained. These nest boxes can become the home for a vari-ety of other wildlife, includ-ing owls, kestrels, squirrels, starlings, and even wasps and bees. In some parts of the Pacific Northwest, hooded mergansers and goldeneye ducks may also use the boxes.

One of the dangers of installing artificial nesting boxes improperly is that it makes the birds vulnerable to predators. Raccoons and squir-rels are two of the most com-mon nest predators of eggs, young, and the incubating hen. The young ducks are vulnera-ble to all the creatures that take young birds, such as house cats, mink, ravens, crows, magpies, and opossums, among others. Nest boxes can be made pred-ator-proof by attaching metal shields around the supporting tree or post.

Riparian areas with bushes and trees that overhang the water provide both food and hiding cover for the ducks. Corn planted near the riparian area, left unharvested and then knocked down, can provide some food for the adults and help attract them. However, natural marsh and swamp areas and healthy natural riparian areas provide the best wood duck habitat. Hunting regula-tions and the artificial nest box program have been important in bringing back the wood-ies, but good habitat is still the key to ensuring the continued presence of these most colorful North American water fowl.

PreDators

Checklist for successful nesting:

1. Wetland (including forest ponds and shrub swamps) or stream within 1/2 mile 2. Snags with 12-inch–deep cavities 3. Riparian areas with roosting and cover vegetation 4. Acorns, hazlenuts, or seeds and fruits of riparian and wetland plant species for adult summer food 5. Forested riparian zones along mountain and northeastern rivers, large lakes, and reser- voirs for the other species of cavity nesting ducks (good wood duck habitat will often suffice for hooded mergansers, as well)

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references:

Bellrose, F. C. 1976. Ducks, Geese and Swans of North America. Stackpole Books, Harrisburg, PA.Fielder, P. 2000. Guidelines for managing wood duck nest boxes in Washington State. Washington Department of Fish and Wildlife, Olympia, WA.Marshall, D. B., M. G. Hunter, and A. G. Contreras, eds. 2003. Birds of Oregon: a General Reference. Oregon State University Press, Corvallis, OR.Wahl, T. R., B. Tweit, and S. Mlodinow, eds. 2005. Birds of Washington: Status and Distribution. Oregon State University Press, Corvallis, OR.

For wood duck box plans and other information on waterfowl, contact: Ducks Unlimited One Waterfowl Way Long Grove, IL 60047 http://www.ducks.org

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titles available in the Woodland Fish & Wildlife series:

Is There a Place for Fish and Wildlife in Your Woodland? ................................. MISC0132Riparian Areas: Fish and Wildlife Havens ........................................................... MISC0133Managing Small Woodlands for Grouse ............................................................... MISC0141Cavity Nesting Ducks .............................................................................................. MISC0142Managing Ponderosa Pine Woodlands for Fish and Wildlife ........................... MISC0158Managing Small Woodlands for Cavity Nesting Birds ...................................... MISC0160Trout in Small Woodland Areas ............................................................................. MISC0161Managing Small Woodlands for Elk...................................................................... MISC0164Coastal Douglas-Fir Forests and Wildlife ............................................................. MISC0168Hawk, Eagle and Osprey Management on Small Woodlands .......................... MISC0169Wetlands as Varied as our Region ......................................................................... MISC0179Wildlife on White Oaks Woodlands ...................................................................... MISC0180 Quail on Small Woodlands ..................................................................................... MISC0187Managing Deer on Small Woodlands ................................................................... MISC0189Beaver, Muskrat, and Nutria on Small Woodlands ............................................. MISC0196Managing Forest Habitats for Neotropical Migrant Songbirds ........................ MISC0198Habitat Management for Bats on Small Woodlands ........................................... MISC0226Managing Western Juniper for Wildlife ................................................................ MISC0286Wildlife in Broadleaf Woodlands of Oregon and Washington .......................... MISC0534Habitat Management for Turkeys on Small Woodlands .................................... MISC0535Managing Pacific Northwest Forests for Band-tailed Pigeons .......................... MISC0564

these publications may be ordered from Wsu extension Publishing and Printing, (800) 723-1763 or http://pubs.wsu.edu/.

You may also download copies at http://www.woodlandfishandwildlife.com.

Woodland Fish and Wildlife

The Woodland Fish and Wildlife Project is a cooperative effort among the World Forestry Cen-ter, Oregon State Department of Forestry, Oregon Department of Fish and Wildlife, Washington State Department of Natural Resources, Oregon State University Extension Service, Washington State Uni-versity Extension, Oregon Association of Conservation Districts, Oregon Small Woodlands Association, Washington Farm Forestry Association, Washington Department of Fisheries, Washington Department of Fish and Wildlife, USDA Natural Resources Conservation Service, the USDA Forest Service, and the Western Forestry and Conservation Association.

The Woodland Fish and Wildlife Project was initiated to provide information on fish and

wildlife management to private woodland owners and managers. It is the intent of the orga-nizations involved in this project to produce publications that will serve as practical guides to woodland owners.

Each publication is intended to be complete in itself. Users may find it convenient to collect all

publications in this series in a three ring binder to form a permanent reference file. Woodland Fish and Wildlife Project publications range from an overview of fish and wildlife opportunities on woodland properties to specific publications concerning techniques for managing individual species.

a Woodland Fish and Wildlife Project Publication

By Ron E. Shay, Executive Director, Woodland Fish and Wildlife Project, and

Jim Bottorff, Washington Department of Natural Resources

Issued by Washington State University Extension and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. WSU Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, sex, religion, age, color, creed, and national or ethnic origin; physical, mental, or sensory disability; marital status or sexual orientation; and status as a Vietnam-era or disabled veteran. Evidence of noncompliance may be reported through your local WSU Extension office. Trade names have been used to simplify information; no endorsement is intended. Revised December 2007. Subject code 440. MISC0142

Reprinting of this publication, in whole or in part, is allowed with written permission from Woodland Fish and Wildlife.