- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding species and migrant. Rare reports during the winter season, mostly of late migrants. The Western Grebe was a rare bird during the Minnesota Breeding Bird Atlas (MNBBA).
As its name implies, the Western Grebe is confined to the western United States and the southern half of the western Canadian Prairie Provinces. Minnesota is on the eastern periphery of its range. A colonial species, there are scattered pockets of abundance throughout its breeding range (Figure 1). Note that Figure 1 combines data for the Western Grebe and Clark’s Grebe. The latter was only identified as a separate species in 1985.
Assigned a Continental Concern Score of 13/20 by Partners in Flight and ranked as a species of Moderate Concern by the North American Waterbird Conservation Plan; designated a Species of Greatest Conservation Need in Minnesota.
Short- to medium-distance migrant; many northern birds winter along the Pacific coast. Southern and far-western populations are permanent residents.
A diver that feeds primarily on fish.
A platform of aquatic vegetation that is usually floating in open water but anchored to emergent or submerged vegetation.
Roberts’s 1932 account of the Western Grebe is brief. He considered it a “rare summer resident” that occurred “irregularly and in limited numbers” along the western border of the state, from Iowa to the Canadian border. At the time there were but 2 nesting records from the late 1800s, both from Heron Lake in Jackson County. The birds continued to be sighted there until 1923. Since Roberts’s time, however, there have been only intermittent reports of the grebe’s presence on the lake (e.g., Koster 1995).
More than 30 years passed before the species was observed nesting at a new location, Lake Traverse in Traverse County in 1935. A total of 9 nests were counted at the site the following year. Additional reports later surfaced from Swan Lake in Nicollet County (1961), Frog Lake in Stevens County (1962), Agassiz National Wildlife Refuge in Marshall County (1969), and Sundberg Lake in Kandiyohi County (1970). Details of each record were discussed in a status summary of Minnesota’s Western Grebes by Burger in 1971. In addition to these new nesting records, the number of migrants passing through the state was increasing, most notably since 1960. Burger’s (1971) overall assessment was that the Western Grebe was increasing in numbers as it expanded eastward into suitable wetland habitat.
Little had changed by the time that Green and Janssen published their updated account in 1975. At about the same time, the newly established Nongame Wildlife Program in the Minnesota Department of Natural Resources launched an initiative to assess the status and distribution of all colonial waterbirds nesting in the state. They augmented a limited number of field surveys with field reports collected from an extensive network of natural resource professionals, professors, birders, and students throughout the state. In their first in-house report in 1977, 20 active Western Grebe colonies were identified (Henderson 1977); three years later, in 1980, the number had increased to 24 (Henderson and Hirsch 1980). A final summary report published in 1985 identified a total of 29 colonies in 17 counties that were active at least one year between 1981 and 1983. Seven of the colonies were located in Big Stone County, and all but 4 of the colonies numbered 50 or fewer nesting pairs. The largest nesting colony was located on Lake Osakis in Todd County and numbered over 200 nesting pairs in 1981 (Guertin and Pfannmuller 1985).
When Janssen (1987) published his updated account, Western Grebes had been documented nesting in 24 of Minnesota’s 87 counties since 1970. Nesting records stretched as far south as Freeborn County in south-central Minnesota and as far east as Hennepin County in east-central Minnesota. In 1998, Hertzel and Janssen (1998) added another 11 counties to the list, further expanding the species’ range eastward to Anoka County in the Twin Cities metropolitan region and to Crow Wing County in northern Minnesota.
Field surveys conducted by the Minnesota Biological Survey (MBS) beginning in the late 1980s documented 48 breeding season locations for the Western Grebe. All but 3 of the locations were confined to the Prairie Parklands and Tallgrass Aspen Parklands ecological provinces, suggesting the species might be retreating westward again (Minnesota Department of Natural Resources 2015).
During the MNBBA, observers reported Western Grebes in 53 of the surveyed atlas blocks and in 33 of the priority atlas blocks. Breeding was confirmed in only 7 blocks (Figures 2 and 3; Table 1). The birds were observed in 27 of Minnesota’s 87 counties and were confirmed breeding in 5 counties. Unlike the absence of reports in the Twin Cities metropolitan region documented by the MBS, 3 of the atlas reports came from the outlying metropolitan counties of Isanti and Wright; there also was 1 “possible” report from a block in northeastern Cass County that also straddled Itasca County. The species was locally abundant in west-central Minnesota but absent from much of southwestern, southeastern, north-central, and northeastern Minnesota. Of the five grebe species that were observed during the MNBBA, Western Grebes comprised only 5.4% of the atlas block records. The Pied-billed Grebe and Red-necked Grebe together accounted for 93% of all observations.
Because none of the MNBBA records included estimates of numbers, it is difficult to ascertain whether populations have changed in recent decades. Clearly the Western Grebe remains more widely distributed than Roberts was able to document in the early 1900s. Elsewhere within its breeding range, the only notable, wide-scale change in the grebe’s distribution has been an expansion in the lower Colorado River valley, where the species is nesting in wetlands on large reservoirs (LaPorte et al. 2013). West of Minnesota, South Dakota documented a substantial increase in the number of Western Grebe colonies between their first and second atlas. During their first atlas (1988–1992), the species was considered rare and local in abundance; during their second atlas (2009–2012) between 40 to 45 nesting colonies were documented each year. The first atlas was conducted during a dry period; the second atlas was conducted during a wet period (Drilling et al. 2016).
*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.