- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding resident and migrant; occasionally observed during the winter at open-water locations, especially in the Twin Cities metropolitan region. The Hooded Merganser was a common species during the Minnesota Breeding Bird Atlas (MNBBA).
The Hooded Merganser is broadly distributed across the eastern half of the United States, with a second, disjunct population in the Pacific Northwest. Although localized breeding populations occur throughout the southeastern United States, the core of the species’ breeding range is in the Great Lakes states. Its distribution and relative abundance, as depicted by the federal Breeding Bird Survey (BBS), are shown in Figure 1.
A game species, the Hooded Merganser has been assigned a Moderately Low Continental Priority by the North American Waterfowl Management Plan. Partners in Flight assigned it a Continental Concern Score of 8/20.
A resident to medium-distance migrant that winters in the southern United States.
A diver that feeds primarily on aquatic insects, small fish, and crustaceans.
A secondary-cavity nester; will use artificial nest boxes. Females have a very high fidelity to the breeding site.
Roberts’s (1932) brief history of the Hooded Merganser’s status in Minnesota is nearly identical to that of every other waterfowl species found in the state: “formerly an abundant migrant and common summer resident throughout the state but now much less numerous and a rather infrequent summer resident.” Overhunting was certainly common in the late 1800s and early 1900s, and no doubt it was largely responsible for the species’ initial decline. The Hooded Merganser is a forest inhabitant dependent on mature trees for nesting cavities. Thus, the wide-scale conversion of forests to agricultural lands in the southern half of the state, coupled with logging of mature, old-growth stands in northern Minnesota, would have had a major impact on the species as well.
Roberts’s account of the species included numerous reports of adults and young broods from locations throughout the state, from the cold, rapid streams of the Arrowhead region to the large wetlands and shallow lakes of the prairie. However, at the time of his writing, only 2 confirmed nesting records (i.e. nests with eggs) were reported: one in Becker County (1886), and one in Kittson County (1899). A female with a brood of half-grown young was also reported in Lake County.
The population eventually rebounded, and by the latter half of the 20th century, the species was reported as a regular summer resident in all but the southwestern region of the state (Green and Janssen 1975; Janssen 1987). It was considered most abundant in the southeast and north-central counties, “very scarce” in the west-central region, and absent from the southwest (Green and Janssen 1975). Janssen’s (1987) breeding distribution map excluded only the southwestern counties, from Lac qui Parle County southeast to central Martin County. He identified 29 counties where nesting had been confirmed since 1970. By 1998, Hertzel and Janssen had confirmed nesting in an additional 13 counties. Apart from a breeding record in Lac qui Parle County, the species was still not confirmed nesting in the southwestern or south-central regions of the state, despite observations of birds in the region throughout the summer.
As of 2014, field staff with the Minnesota Biological Survey tallied 180 Hooded Merganser breeding season locations during their fieldwork. The majority of records were from the Arrowhead region of northeastern Minnesota, the north-central counties of Beltrami and Clearwater, and from southwestern and south-central Minnesota (Minnesota Department of Natural Resources 2016).
During the MNBBA, participants reported 1,180 Hooded Merganser records from 18.8% (898/4,764) of the surveyed atlas blocks and from 20.5% (478/2,337) of the priority blocks. Breeding was confirmed in 386 (8.1%) of the surveyed blocks (Figures 2 and 3; Table 1). The birds were observed in all but 3 of Minnesota’s 87 counties (Chisago, Mower, and Wilkin) and were confirmed breeding in 73 counties. Overall, they were distributed across the entire state but were least abundant in the Red River valley, in the peatlands of north-central Minnesota, and in the southeast region. Although records were sparsely distributed across southern Minnesota, breeding was confirmed in 24 of the 31 counties located south of the Minnesota River.
The landcover suitability map for the Hooded Merganser (Figure 4) illustrates the suitability of habitats throughout Minnesota. The only extensive region of unsuitable habitat is in north-central Minnesota in the Northern Minnesota and Ontario Peatlands Section. Outside of the forested regions of northern and central Minnesota, riparian habitats throughout western and southern Minnesota provide suitable habitat, as does the greater Twin Cities metropolitan region, where the deployment of artificial nest boxes likely improves nesting opportunities for the species.
The Hooded Merganser was the fifth most frequently reported waterfowl species in the state during the atlas, behind the Canada Goose, Mallard, Wood Duck, and Blue-winged Teal. Clearly this spectacular little duck is faring quite well in Minnesota and has found suitable wetlands and nesting cavities even in the small woodlots that are scattered throughout the agricultural landscape. The widespread placement of Wood Duck nest boxes in this region has likely benefited the species as well.
Historically, Hooded Mergansers likely occurred throughout North America’s eastern deciduous forest before it was cleared, as well as in the mountainous regions of the western states. Small breeding populations still occur in many of these areas but are usually small in number and localized in distribution. Although the species now occupies most of its former breeding range, populations tend to be more localized in distribution and smaller (Dugger et al. 2009). More recently, Ontario witnessed no overall change in the merganser’s distribution between its first (1982–1985) and second (2001–2005) atlases (Cadman et al. 2007). Michigan documented a significant increase in the number of townships reporting Hooded Mergansers during its second atlas (2002–2008), although the species’ distribution changed little other than along the most southern two tiers of counties. Quite rare in this region of the state during the first atlas (1982–1988), they were reported from all but 3 of the counties during the second atlas (Chartier et al. 2013).
*Note that the definition of confirmed nesting of a species is different for Breeding Bird Atlas projects, including the definition used by the Minnesota Breeding Bird Atlas, compared with a more restrictive definition used by the Minnesota Ornithologists’ Union. For details see the Data Methods Section.