- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding resident and migrant; birds are occasionally reported during the winter months. The Swamp Sparrow was an abundant species during the Minnesota Breeding Bird Atlas (MNBBA).
A northern species, the Swamp Sparrow’s breeding range stretches across much of Canada and the northern tier of the United States, from the eastern Great Plains and Minnesota, east across the Great Lakes and New England. The Swamp Sparrow reaches its highest breeding densities in Minnesota and Newfoundland (Figure 1).
Assigned a Continental Concern Score of 6/20 by Partners in Flight.
A short-distance migrant that winters in the southeastern United States and Mexico. Populations along the southern periphery of the species’ breeding range, in the southern Great Lakes and southern New England, are year-round residents.
An omnivorous ground forager and foliage gleaner that consumes invertebrates, seeds, and fruits.
Open-cup nest located just above the ground or water and supported by surrounding herbaceous or shrub vegetation; occasionally located on the ground.
In the late 1800s and early 1900s, Roberts (1932) considered the Swamp Sparrow a common breeding species across the state, although he noted that it was less frequently encountered in the western grasslands, particularly along the Red River valley. Commenting on its favorite haunts, he wrote:
The Swamp Sparrow, as its name implies, makes its home chiefly in the wetter portions of bogs and marshes where the cattails, rushes, and rank grasses flourish. Sluggish meadow streams, bordered by low willows and alders, are much to its liking. It is more secretive in its habits than the Song Sparrow and is loath to leave the concealment of its retreats.
At the time, confirmed nesting records (nests with eggs) were available from Hennepin, Jackson, Marshall, Otter Tail, and Sherburne Counties. Inferred nesting records (young out of the nest and adults carrying food) were available from Aitkin County and Itasca State Park.
Little had changed more than 40 years later when Green and Janssen (1975) prepared an updated account of the species’ status and commented that the Swamp Sparrow occurred statewide, wherever suitable wetland habitat was available. A few years later, Janssen (1987) identified 11 counties where nesting had been confirmed since 1970. All but 2, Goodhue and Le Sueur, were north of the Minnesota River valley. He noted that the species was particularly abundant in the “wooded swamps” of northern Minnesota, where 7 of the 11 records occurred. Five more counties were added by Hertzel and Janssen (1998), bringing the total list to 16. Thirteen of the 16 counties were located north of the Twin Cities; the remaining 3 were in southeastern Minnesota.
Field staff with the Minnesota Biological Survey documented 2,249 breeding season locations for the Swamp Sparrow. Observations were least numerous in the intensively cultivated regions of the Red River valley and the upper Minnesota River valley and in southeastern Minnesota (Minnesota Department of Natural Resources 2016).
MNBBA participants reported a total of 5,057 Swamp Sparrow records in 52.2% (2,489/4,772) of the surveyed atlas blocks and in 62.3% (1,457/2,337) of the priority blocks. Breeding evidence was documented in 152 blocks (Figures 2 and 3; Table 1). The birds were reported in all of Minnesota’s 87 counties and were confirmed breeding in 39 counties, 37 of which were located north of the Minnesota River (2 blocks straddled both Scott and Dakota Counties). Again, the species was virtually absent from the intensively cultivated Red River valley north of Wilkin County and was sparsely distributed in southeastern Minnesota. Based on MNBBA records, the Swamp Sparrow was the third most abundant sparrow in Minnesota, following the Song Sparrow and Chipping Sparrow.
Atlas data were used to develop a model to predict the relative abundance of Swamp Sparrows across Minnesota (Figure 4). This shrubby wetland–dependent species was predicted to have its highest probability of occurrence in the extensive wetland landscape of the Agassiz Lowlands Subsection and Tallgrass Aspen Parklands Province just north and west of Red Lake. Interestingly, as early as 1900, Roberts (1932) commented on how abundant the species was in this region. “Along the Moose River, in western Beltrami County, where the Swamp Sparrow was abundant in July, 1900, the writer heard it singing frequently during the midnight hours on bright moonlight nights.” Although there are small pockets of high abundance predicted throughout Minnesota, this expansive, largely inaccessible landscape provides ideal habitat. Miles of flat, poorly drained lake deposits, relics of Glacial Lake Agassiz, are covered by bogs, swamps, and fens that provide the wet habitat and low vegetation that characterize most Swamp Sparrow habitats (Minnesota Department of Natural Resources 2003). Areas of lowest abundance correlate with high development, including the Twin Cities, Rochester, and St. Cloud.
Over the years, field biologists and birders have consistently commented on the broad distribution of the Swamp Sparrow across Minnesota. Yet, because it resides exclusively in wetland habitats, a more in-depth assessment of its distribution and abundance have been lacking. Data gathered by the MNBBA provide a more informed assessment of its relative abundance across key ecological regions and its dependence on an entire landscape of remote wetlands that are largely inaccessible.
In his comprehensive review of the species, Mowbray (1997) noted only two minor changes to the Swamp Sparrow’s breeding range. The first was an apparent expansion along the mid-Atlantic coast in the mid-1900s, from eastern Maryland north to the Hudson River; the second was the species’ extirpation from northeastern Missouri. Breeding bird atlases conducted in the northern Great Plains and Upper Midwest consistently confirmed the species’ widespread occurrence with only a few distributional changes. In Wisconsin, the state’s first atlas (1995–2000) revealed the species was far more abundant and widespread in northern Wisconsin than previous accounts had described (Cutright et al. 2006). In South Dakota the state’s first atlas (1988–1992) found Swamp Sparrows widely distributed through the eastern half of the state but restricted to the northeastern corner of the state during the second atlas (2009–2012) (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.