Hooded Merganser (Lophodytes cucullatus)

Photo by Jack BartholmaiHooded Merganser by Jack BartholmaiHooded Merganser distribution map


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.

Life History

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


 Contact Information

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

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