Photo by Jack Bartholmai

Status/Protection

• Global Rank: G5 Key to global and state ranks
• State Rank: S4B
• WBCI Priority: WFOWL

Population Information

Federal BBS information can be obtained at http://www.mbr-pwrc.usgs.gov/bbs/bbs.html by clicking on Trend Estimates and selecting the species in question. All estimates are for 1966-2005.

*Note: There are important deficiencies with these data. These results may be compromised by small sample size, low relative abundance on survey route, imprecise trends, and/or missing data. Caution should be used when evaluating this trend.

• Federal Breeding Bird Survey: significant increase*
• Federal Breeding Bird Survey (WI): non-significant increase*
• Federal Breeding Bird Survey (BCR 23): N/A
• Federal Breeding Bird Survey (BCR 12): non-significant increase
• North American Waterfowl Management Plan: increase (NAWMP 2004)
• WSO Checklist Project: significant increase (1983-2007)

Life History

• Breeding Range: Ontario south to Louisiana and east to the Atlantic Coast; also the Pacific Northwest (Dugger et al. 1994).
• Breeding Habitat: Northern Sedge Meadow and Marsh, Southern Sedge Meadow and Marsh, Emergent Marsh, Wild Rice, and Bottomland Hardwood.
• Nest: Cavities in live or dead trees, usually in close proximity to water (Dugger et al. 1994).
• Nesting Dates: Eggs: early April to mid-August (Verch 2006).
• Foraging: Surface dives (Ehrlich et al. 1988).
• Migrant Status: Short-distance migrant.
• Habitat use during Migration: Inland Open Water, Northern Sedge Meadow and Marsh, Southern Sedge Meadow and Marsh, Emergent Marsh, and Wild Rice.
• Arrival Dates: Early March to late April (Robbins 1991).
• Departure Dates: Mid-September to late November (Robbins 1991).
• Winter Range: Primarily southeastern U.S. and Pacific Northwest but can occur throughout the southern U.S. (Dugger et al. 1994).
• Winter Habitat: Shallow, freshwater and brackish bays and estuaries; also tidal creeks and ponds (Dugger et al. 1994).

Habitat Selection

Throughout its range, the Hooded Merganser inhabits mature riparian forests along major river systems and other forested wetland habitats. It nests in natural tree cavities as well as artificial nest boxes that are within close proximity to water (Dugger et al. 1994). Brood habitat in Wisconsin is more commonly associated with fast-moving rivers with >20% cobble bottom rather than lakes or other areas of standing water (Kitchen and Hunt 1969). These conditions may support higher densities of preferred prey items, such as small fish, aquatic invertebrates, crayfish, and other crustaceans (Kitchen and Hunt 1969, Dugger et al. 1994).

Habitat Availability

Although Robbins (1991) claimed breeding to be confined to the northern part of the state, breeding activity in the southern half of the state has been documented in historical accounts (Kumlien and Hollister 1903) as well as recent Breeding Bird Atlas work (Verch 2006). This retraction and expansion from the southern half of the state may be indicative of landscape-scale productivity and recruitment levels or smaller-scale resource availability factors. The maturation of hardwood forests in the eastern U.S. has been implicated in range expansion of this species (Soulliere and Rusch 1996). In Wisconsin, bottomland hardwood and other floodplain forests have been greatly reduced, but have fared better than many of Wisconsin’s other native habitats. It is estimated that floodplain forests in moderate to high quality condition cover 8% of their original extent (Mossman 1988). Invasive plant species, particularly reed canary grass, may impede regeneration in floodplain forests and development pressures also threaten remaining floodplain forest tracts (WDNR 2005).

Population Concerns

It is difficult to ascertain the population status of this species because it is not well-sampled by traditional waterfowl surveys. The North American Waterfowl Management Plan suggests a continent-wide population estimate of 350,000 individuals with an increasing population trend (NAWMP 2004). In Wisconsin, there is anecdotal evidence that this species has fluctuated from being very common in the late nineteenth century (Kumlien and Hollister 1903) to uncommon as recent as the 1980s (Robbins 1991) and now appears to be increasing once again (NAWMP 2004, Verch 2006). Data from the Wisconsin Spring Duck Survey (1973-2007) indicate a dramatic increase in the number of Hooded Mergansers detected, particularly in the last five years (R. Gatti pers. comm.). Surveys conducted in northern Wisconsin from 1987-1991 recorded Hooded Mergansers as the fifth most common in breeding pairs and the third most common in broods (Bubb and Gregg 2002, Caithamer et al. 2002) and it also breeds regularly in the southern half of the state (Verch 2006).

Overhunting may have contributed to declines in the early twentieth century but now is not believed to be problematic. Today, habitat alteration and loss of nest cavities likely limit Hooded Mergansers in some areas (Dugger et al. 1994).

Recommended Management

Management actions that maintain and restore large tracts of unfragmented floodplain forests will benefit this species and others occurring within these landscapes, such as Red-shouldered Hawk, Least Flycatcher, and Yellow-bellied Sapsucker. Managers are encouraged to retain trees with nest cavities and/or retain snags and stumps in floodplain forests. Artificial nest boxes may provide alternative nesting substrates in fragmented or degraded riparian areas. Water quality also is an important consideration and can be improved by controlling sedimentation, agricultural runoff, and other pollutants (Dugger et al. 1994). Managers should avoid or limit use of pesticides on managed wetlands to minimize impacts on prey resources.

Research Needs

The basic ecology of Hooded Mergansers remains poorly known. More information on seasonal food habits, foraging behavior, and foraging habitat preferences is needed (Dugger et al. 1994). Improved population monitoring and trend estimates would help guide harvest management.    

Information Sources

• Cornell Lab of Ornithology species account: http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Hooded_Merganser.html
• North American Waterfowl Management Plan: http://www.fws.gov/birdhabitat/NAWMP/Planstrategy.shtm
• Upper Mississippi River Great Lakes Joint Venture Implementation Plan: http://www.fws.gov/midwest/NAWMP/documents/WaterfowlManagementPlan.pdf
• Waterfowl Population Status report: http://www.fws.gov/migratorybirds/reports/status06/waterfowl%20status%202006.pdf
• Wisconsin Breeding Bird Atlas http://www.uwgb.edu/birds/wbba/
• Wisconsin Department of Natural Resources (WDNR). 1992. Upper Mississippi River and Great Lakes region joint venture – Wisconsin plan. Madison, WI.

References

• Bub, B.R., and L.E. Gregg. 2002. Summary of waterfowl brood surveys in northern Wisconsin, 1987-1991. WDNR unpublished report, Bureau of Research. Madison. 17pp.
• Caithamer, D.F., P.W. Rasmussen, and L.E. Gregg. 2002. Population estimates of waterfowl in northern Wisconsin, 1987-1991. WDNR unpublished report, Bureau of Research. Madison. 22pp.
• Dugger, B.D., K.M. Dugger, and L.H. Fredrickson. 1994. Hooded Merganser (Lophodytes cucullatus). In The Birds of North America, No. 98 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.
• Ehrlich, P.R., D.S. Dobkin, and D. Wheye. 1988. The birders handbook: a field guide to the natural history of North American birds. Simon & Schuster, Inc. New York.
• Kitchen, D.W. and G.S. Hunt. 1969. Brood habitat of the Hooded Merganser. Journal of Wildlife Management 33: 605-609.
• Kumlien, L. and N. Hollister. 1903. The birds of Wisconsin. Wisconsin Natural History Society Bulletin 3(1-3): 1-43.
• Mossman, M.J. 1988. Birds of southern Wisconsin floodplain forests. Pass. Pigeon 50(4): 321-337.
• North American Waterfowl Management Plan, Plan Committee. 2004. North American Waterfowl Management Plan 2004. Implementation Framework: Strengthening the Biological Foundation. Canadian Wildlife Service, U.S. Fish and Wildlife Service, Secretaria de Medio Ambiente y Recursos Naturales, 106 pp.
• Robbins, S. D. 1991. Wisconsin birdlife: population & distribution, past & present. Univ. of Wisconsin Press, Madison, WI.
• Soulliere, G.J. and T.P. Rusch. 1996. Nesting characteristics of Hooded Mergansers, Wood Ducks, European Starlings, and Tree Swallows in Wisconsin. Journal of Field Ornithology 67(1): 100-104.
• Verch, D. 2006. Hooded Merganser. In Atlas of the Breeding Birds of Wisconsin. (N.J. Cutright, B.R. Harriman, and R.W. Howe, eds.). The Wisconsin Society for Ornithology, Inc. 602pp.
• Wisconsin Department of Natural Resources (WDNR). 2005. Wisconsin’s Strategy for Wildlife Species of Greatest Conservation Need. Madison, WI.

 Contact Information

• Compiler: Kim Kreitinger, K.Kreitinger@gmail.com
• Editor: