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Cavity Nesting Ducks
Barrow's Goldeneye - Bucephala islandica Common Goldeneye - Bucephala clangula Hooded Merganser - Lophodytes cucullatus Bufflehead - Bucephala albeola Wood Duck - Aix sponsa |
GENERAL RANGE AND WASHINGTON DISTRIBUTION
These five species of cavity-nesting ducks vary in distribution. The breeding and wintering ranges of the Barrow's goldeneye (Bucephala islandica) and the bufflehead (Bucephala albeola) extend from Alaska to California. The wood duck (Aix sponsa) and hooded merganser (Lophodytes cucullatus) winter south of Alaska and breed from British Columbia southward. The common goldeneye winters from Alaska to California and breeds in isolated areas of Washington northward to Alaska (Bellrose 1976).
 Breeding Distribution of the Bufflehead (Bucephala Clangula) in Washington. Map derived from GAP Analysis of Washington (Smith et al. 1997).
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Washington is one of a very few states where all 5 species are known to breed (Matt Monda, personal communication). The common goldeneye breeds in a few isolated areas in northeastern Washington. Buffleheads are only known to breed south of Spokane on Turnbull National Wildlife Refuge and at Big Meadow Lake in Pend Oreille County (Smith et al. 1997). The Barrow's goldeneye is more widespread and breeds within the Cascades and in north-central Washington. A unique population of Barrow's goldeneye nest in cavities within the talus slopes and basalt cliffs surrounding Lake Lenore and Alkali Lake in central Washington (Matt Monda, personal communication). Breeding areas for hooded mergansers and wood ducks are more widespread, primarily in the western part of the state, but they also breed in eastern Washington where adequate habitat occurs (Smith et al. 1997). In addition, large concentrations of breeding wood ducks occur in the Yakima valley (Matt Monda, personal communication).
All five species can be found in larger numbers during migration. Though wood ducks typically winter further south than Washington, significant wintering numbers can be found in the Yakima Valley and the Columbia River estuary. Goldeneyes and buffleheads winter in large numbers on Puget Sound and larger rivers. Hooded Mergansers are less common but winter in a wide variety of habitats (Matt Monda, personal communication).
RATIONALE
Cavity-nesting ducks provide recreation to hunters and bird watchers, and they are vulnerable to loss of nesting habitat. These species require nesting cavities within trees and snags, which are commonly lost through commercial forestry, firewood cutting, and shoreline development. All but the wood duck exhibit low productivity and low population sizes, breed for the first time at an older age, and are poor pioneers of unoccupied habitats (Goudie et al. 1994). Common goldeneye and bufflehead are the least common breeding ducks in the state. Loss of suitable nesting sites will eliminate use of an area by breeding birds.
HABITAT REQUIREMENTS
In Washington, cavity-nesting ducks nest primarily in late-successional forests and riparian areas adjacent to low gradient rivers, sloughs, lakes, and beaver ponds (Thomas 1979, Brown 1985, Parker 1990). Animal matter can comprise over 75% of the diets of the hooded merganser, bufflehead, common goldeneye and Barrow's goldeneye. These species feed primarily on aquatic insects, mollusks, crustaceans, and small fish (Gauthier 1993, Dugger et al. 1994, Fitzner and Gray 1994, Eadie et al. 1995, Hepp and Bellrose 1995). Wood ducks up to 6 weeks old depend on animal matter, while older ducklings and adult wood ducks feed on aquatic and emergent plants, acorns, grain, and other seeds (Bellrose and Holm 1994).
Nest Site Characteristics
These 5 species of ducks nest almost exclusively in tree cavities, which offer protection from weather and predators. They are secondary cavity nesters, using cavities created by large woodpeckers or by decay or damage to the tree. Cavity use is dependent on the proximity of suitable brood habitat, predator levels, and competition (and perhaps brood parasitism) from the other cavity-nesting species (Peterson and Gauthier 1985, Dugger et al. 1994, Eadie et al. 1995, Robb and Bookhout 1995). Nest site fidelity is common, especially at successful nests (Dow and Fredga 1984, Hepp and Kennamer 1992, Gauthier 1993, Dugger et al. 1994). Population levels of cavity-nesting ducks can be related to the availability of nesting sites (Dow and Fredga 1984, Gauthier 1993, Dugger et al. 1994, Eadie et al. 1995, Hepp and Bellrose 1995).
In general, minimum cavity dimensions that will accommodate all 5 species include an entrance hole at least 9 cm (3.5 in) in diameter, with the internal cavity 25 cm (10 in) deep and 19 cm (7.5 in) in diameter (Gauthier 1993, Dugger et al. 1994, Eadie et al. 1995, Robb and Bookhout 1995). The bufflehead, however, appears to prefer smaller cavity entrances (6.5 cm diameter [2.5 in]; flicker nests are ideal) which may reduce nest-site competition and brood parasitism from larger ducks (especially goldeneyes) (Gauthier 1993). Hooded mergansers have less specific nest-cavity preferences, but they prefer nest sites that are within or very near brood habitat (Dugger et al. 1994). Nest trees should have diameters 30 cm (12 in) (Soulliere 1988), but all 5 species typically use nest trees >60 cm (24 in) dbh. These ducks will use cavities that occur above 20 m (66 ft) in trees, but they generally use cavities 2-15 m (6-49 ft) above the ground or water. The canopy around a cavity is generally open and does not overhang the entrance (Bellrose 1976). Optimal density of potential nest trees is 12.5/ha (5/acre) (Sousa and Farmer 1983).
Brood Habitat
Shallow wetlands within 0.8 km (0.5 mi) of cavities provide optimal brood habitat for all cavity-nesting ducks. Wood ducks typically use habitats with 50-75% overhanging woody vegetation and/or emergent vegetation for brood escape cover (Sousa and Farmer 1983); all 5 species use downed logs or low islands for loafing (Webster and McGilvrey 1966, Gauthier 1993, Dugger et al. 1994, Eadie et al. 1995, Hepp and Bellrose 1995). Both goldeneye species and the bufflehead typically use more open water with less emergent vegetation as brood habitat (Gauthier 1993, Dugger et al. 1994, Eadie et al. 1995). Common goldeneyes prefer acidic and fishless waters where there is little or no competition from fish for acid-tolerant aquatic insects (Gauthier 1993, Poysa and Virtanen 1994, Eadie et al. 1995).
LIMITING FACTORS
Population levels of cavity-nesting ducks can be limited by the availability of suitable nesting sites, adequate brood escape cover, foraging areas, nest predation, and nest parasitism (Dow and Fredga 1984, Gauthier 1993, Bellrose and Holm 1994, Dugger et al. 1994, Eadie et al. 1995, Hepp and Bellrose 1995). Human disturbance of nesting ducks may affect productivity. In addition, Barrow's goldeneye, common goldeneye, hooded merganser, and bufflehead all exhibit low productivity and low population sizes, breed for the first time at an older age, and are poor pioneers of unoccupied habitats (Goudie et al. 1994). Destruction of cavity trees can eliminate these species from an area (Matt Monda, personal communication).
The use of herbicides or pesticides near wetlands may affect cavity-nesting ducks by lowering the numbers of invertebrates, and by adversely affecting aquatic and emergent vegetation. All of these ducks are known to accumulate toxins in their tissues, especially in areas where toxins are elevated, such as downstream from mines, pulp and paper mills, and in the Great Lakes (Blus et al. 1993, Swift et al. 1993, Vermeer et al. 1993, Champoux 1996).
MANAGEMENT RECOMMENDATIONS
An adequate supply of nest cavities is the key to supporting populations of cavity-nesting ducks in Washington. Land management activities designed to promote healthy populations of these 5 duck species should ensure a continuous supply of available nest cavities.
Snags and cavity trees near suitable wetlands should be preserved and created to achieve a minimum density of 12.5 potential nest cavities/ha (5/ac) (McGilvrey 1968). Snags and cavity trees should have a minimum diameter of 30 cm (12 in), although a diameter of 60 cm (24 in) is preferred (McGilvrey 1968).
In general, the following nest cavity characteristics will accommodate all five species and should be considered when evaluating potential nest sites:
Large woody debris and downed logs should be present, as well as low islands for breeding and brood use (McGilvrey 1968). Flooded timber should not be logged, and woody vegetation along the shores of nesting and brood areas should be retained. In some situations, flooding standing or downed timber may be used to create snags and brood habitat (McGilvrey 1968).
Predator-proof nest boxes for cavity nesting ducks can be used in areas where natural cavity sites are limited but other habitat requirements are met (Bellrose 1976). However, it is unknown how nest boxes affect natural selection or species fitness over time. Wood ducks show strong site fidelity to where they were born or where they have previously bred successfully, and those born in nest boxes may prefer to nest in them as adults (Richardson and Knapton 1993). In some situations, it may not be suitable to consider nest boxes as permanent substitutes for natural cavities. The decision to provide nest boxes to supplement existing cavities or nest boxes should consider occupancy rates of existing suitable nest sites. If existing sites are under-used, for instance, other habitat factors may be limiting).
Wood duck boxes should be designed and placed following the recommendations of Bellrose and Holm (1994). Boxes for the other four species should follow the guidelines provided by Lumsden et al. (1980) and Gauthier (1993). Nest boxes for cavity nesting ducks are commonly made out of rough-cut lumber. Other materials that can be used include sheet metal and slab wood (Bellrose and Holm 1994).
To minimize the impacts of brood parasitism, predation, and starling use, nest boxes for wood ducks should be placed far enough apart so that one is not visible from the other. (Fellman 1993, Bellrose and Holm 1994, Semel and Sherman 1995). Bellrose and Holm (1994) recommend a minimum of 46 m (50 yd) between nest box structures. Nest box placement can affect clutch size, rates of brood parasitism, and hatching success in wood ducks. Traditionally placed nest boxes that are grouped together with highly visible entrances often suffer from higher rates of brood parasitism and produce less ducklings over time than nest boxes placed in trees out of sight of each other (Fellman 1993, Semel and Sherman 1995).
In areas supporting wood ducks, mast-producing trees and shrubs, such as oaks (Quercus garryana) and hazelnuts (Corylus cornuta), should be maintained.
The use of pesticides or herbicides may negatively affect these species. If pesticide or herbicide use is planned for areas where cavity-nesting ducks occur, refer to Appendix A for contacts useful for assessing pesticides, herbicides, and their alternatives.
REFERENCES
Bellrose, F. C. 1976. Ducks, geese, and swans of North America. Stackpole Books, Harrisburg, Pennsylvania, USA.
Bellrose, F. C., and D. J. Holm. 1994. Ecology and management of the wood duck. Stackpole Books, Harrisburg, Pennsylvania, USA.
Blus, L. J., C. J. Henny, D. J. Hoffman, and R. A. Grove. 1993. Accumulation and effects of lead and cadmium on wood ducks near a mining and smelting complex in Idaho. Ecotoxicology 2:139-154.
Brown, E. R., technical editor. 1985. Management of wildlife and fish habitats in forests of western Oregon and Washington, Volumes 1 and 2. U.S. Forest Service, Pacific Northwest Region, Portland, Oregon, USA. Publication Number R6-F&WL-192-1985.
Champoux, L. 1996. PCBs, dioxins and furans in hooded merganser (Lophodytes cucullatus), common merganser (Mergus merganser), and mink (Mustela vison) collected along the St. Maurice River near La Tuque, Quebec. Environmental Pollutants 92:147-153.
Dow, H., and S. Fredga. 1984. Factors affecting reproductive output of the goldeneye duck. Journal of Animal Ecology 53:679-692.
Dugger, B. D., K. M. Dugger, and L. H. Fredrickson. 1994. Hooded merganser (Lophodytes cucullatus). Number 98 in A. Poole and F. Gill, editors. The Birds of North America, American Ornithologists Union and Academy of Natural Science, Philadelphia, Pennsylvania, USA.
Eadie, J. M., M. L. Mallory, and H. G. Lumsden. 1995. Common goldeneye (Bucephala clangula). Number 170 in A. Poole and F. Gill, editors. The Birds of North America. American Ornithologists Union and Academy of Natural Science, Pennsylvania, USA.
Fitzner, R. E., and R. H. Gray. 1994. Winter diet and weights of Barrow's and common goldeneyes in southcentral Washington. Northwest Science 68:172-177.
Gauthier, G. 1993. Bufflehead (Bucephala albeola). Number 67 in A. Poole and F. Gill, editors. The Birds of North America. American Ornithologists Union and Academy of Natural Science, Pennsylvania, USA.
Goudie, R. I., A. V. Kondratyev, S. Brault, M. R. Petersen, B. Conant, and K. Vermeer. 1994. The status of sea ducks in the North Pacific Rim: toward their conservation and management. Transactions of North American Wildlife and Natural Resources Conference 59:27-49.
Hepp, G. R., and F. C. Bellrose. 1995. Wood duck (Aix sponsa). Number 169 in A. Poole and F. Gill, editors. The Birds of North America. American Ornithologists Union and Academy of Natural Science, Pennsylvania, USA.
Hepp, G. R., and R. A. Kennamer. 1992. Characteristics and consequences of nest-site fidelity in wood ducks. Auk 109:812-818.
Lumsden, H. G., R. E. Page, and M. Gunthier. 1980. Choice of nest boxes by common goldeneye in Ontario. Wilson Bulletin 92:497-505.
McGilvrey, F. 1968. A guide to wood duck production habitat requirements. Bureau of Sport Fish and Wildlife Research, Publication number 60.
Parker, R. 1990. Statewide waterfowl survey and inventory: waterfowl productivity. July 1, 1989, through June 30, 1990. Unpublished Report, Washington Department of Wildlife, Olympia, Washington, USA.
Peterson, B., and G. Gauthier. 1985. Nest site use by cavity-nesting birds of the Cariboo Parkland, British Columbia. Wilson Bulletin 97:319-331.
Poysa, H., and J. Virtanen. 1994. Habitat selection and survival of common goldeneye (Bucephala clangula) broods - preliminary results. Hydrobiologia 279/280:289-296.
Robb, J. R., and T. A. Bookhout. 1995. Factors influencing wood duck use of natural cavities. Journal of Wildlife Management 59:372-383.
Ryan, D. C., R. J. Kawula, and R. J. Gates. 1998. Breeding biology of wood ducks using natural cavities in southern Illinois. Journal of Wildlife Management 62:112-123.
Semel, B., and P. W. Sherman. 1995. Alternative placement strategies for wood duck nest boxes. Wildlife Society Bulletin 23:463-471.
Smith, M. R., P. W. Mattocks, Jr., and K. M. Cassidy. 1997. Breeding birds of Washington state. Volume 4 in K. M. Cassidy, C. E. Grue, M. R. Smith and K. M. Dvornich, editors. Washington State GAP analysis - final report. Seattle Audubon Society publications in zoology number 1, Seattle, Washington, USA.
Soulliere, G. 1988. Density of suitable wood duck nest cavities in a northern hardwood forest. Journal of Wildlife Management 52:86-89.
Sousa, P., and A. Farmer. 1983. Habitat suitability index models: wood duck. U.S. Fish and Wildlife Service, FWS/OBS82/10.43.
Swift, B. L., R. E. Foley, and G. R. Batcheller. 1993. Organochlorines in common goldeneyes wintering in New York. Wildlife Society Bulletin 21:52-56.
Thomas, J. W. 1979. Wildlife habitats in managed forests: the Blue Mountains of Oregon and Washington. U.S. Forest Service, Agricultural Handbook Number 553.
Vermeer, K., W. J. Cretney, J. E. Elliott, R. J. Norstrom, and P. E. Whitehead. 1993. Elevated polychlorinated dibenzodioxin and dibenzofuran concentrations in grebes, ducks, and their prey near Port Alberni, British Columbia, Canada. Marine Pollutants Bulletin 26:431-435.
Webster, C., and F. McGilvrey. 1966. Providing brood habitat for wood ducks. Pages 70-75 in J. B. Trefethen, editor. Wood duck management and research: a symposium. Wildlife Management Institute, Washington, D.C., USA.
PERSONAL COMMUNICATION
Matt Monda, Biologist
Washington Department of Fish and Wildlife
Ephrata, Washington
KEY POINTS
Habitat Requirements
Management Recommendations
