- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding resident and migrant; the Grasshopper Sparrow was an uncommon species during the Minnesota Breeding Bird Atlas (MNBBA).
Found primarily from the Great Plains south to southern Texas and east to the Atlantic coast, from southern Maine south to northern Georgia. Populations are found in the very southern regions of the Canadian Prairie Provinces and in southwestern Ontario and southern Quebec. Farther west, local populations are found in the northwestern United States and in California. The Grasshopper Sparrow attains its highest breeding densities in the Great Plains from North Dakota south through Nebraska (Figure 1).
Assigned a Continental Concern Score of 12/20 and designated a Common Bird in Steep Decline by Partners in Flight; designated a Species in Greatest Conservation Need by the Minnesota Department of Natural Resources and a Target Conservation Species by Audubon Minnesota.
A short- to medium-distance migrant that winters in the southern United States and Central America; populations along the southern periphery of the breeding range are year-round residents..
An omnivorous ground forager that feeds on insects, especially grasshoppers, and seeds.
An open-cup nest that often has a partial dome; placed on the ground at the base of a clump of grasses or forbs.
Located on the northern periphery of its breeding range in Minnesota, the Grasshopper Sparrow is an inconspicuous and secretive bird with a faint, insect-like trill for a song. Roberts (1932) described the species as a breeding resident throughout the state. Most abundant on the western prairies, it even extended, albeit sparingly, into the northern forests “wherever there are extensive clearings and sparsely wooded areas.” Roberts provided several examples of its northern habitats, including records from the counties of St. Louis (Lake Vermilion), Lake (Two Harbors), Pine, Hubbard, and southern Beltrami. Confirmed nesting records (nests with eggs or young) were limited to western and east-central Minnesota and included Hennepin, Jackson, Polk, Sherburne, and Wilkin Counties. An inferred breeding record (large young) was reported from Ramsey County.
The species garnered little attention over the years from biologists and birders alike. Even Roberts’s account in 1932 was one of the shortest accounts he prepared for his two-volume treatise for such a common and widespread species. Only two, very short notes have been published in the state ornithological journal, The Loon, since its inception in 1929 through 2017.
Green and Janssen’s (1975) updated account of the species also described it as a statewide resident during the breeding season. Although there were summer records from as far north as Cook, northern St. Louis, Lake of the Woods, and Roseau Counties, it was rare in the northeast and north-central regions of the state. Several years later, Janssen (1987) suggested the species might be spreading north into Roseau and Kittson Counties “where suitable open grassy habitat exists.” Despite its rather broad distribution, nests were particularly difficult to locate. Janssen identified only 7 counties where nesting was confirmed since 1970: Brown, Clay, Cottonwood, Norman, Ramsey, Rock, and Wabasha. By 1998 Hertzel and Janssen added another 4 counties to the list: Aitkin, Kandiyohi, Sherburne, and Stevens.
Field biologists with the Minnesota Biological Survey (MBS) have documented 529 breeding season locations since their field surveys began in the late 1980s. The overwhelming majority of records are outside of the Laurentian Mixed Forest Province; the few reports within this region are confined largely to the western and southern borders of the province. In northwestern Minnesota, records were found as far north as Marshall, Kittson, and Roseau Counties (Minnesota Department of Natural Resources 2016).
MNBBA participants reported 761 Grasshopper Sparrow records from 9.8% (463/4,747) of the surveyed atlas blocks and from 11.9% (277/2,337) of the priority blocks. Breeding evidence was gathered in 25 blocks (Figures 2 and 3; Table 1). The birds were reported from 78 of Minnesota’s 87 counties, and breeding was confirmed in 22 counties, including at a site in St. Louis County (1 block straddled 2 counties: Lac qui Parle and Chippewa). The latter report was from a reclaimed taconite tailings basin along the Iron Range. Seventeen of the counties where breeding evidence was gathered were new to the list published by Hertzel and Janssen in 1998. The majority of atlas reports were from the Prairie Parkland and Eastern Broadleaf Forest Provinces. Compared to data compiled by the MBS, the atlas documented more reports from the Tallgrass Aspen Parklands Province and more reports farther east into the Laurentian Mixed Forest Province.
During the atlas period, birders also reported confirmed nesting records in 3 additional counties: (1) a summer 2010 report of adults carrying food in Crow-Hassan Park Reserve in Hennepin County; (2) a summer 2011 report of adults carrying food in Grey Cloud Dunes Scientific and Natural Area in Washington County; and (3) a summer 2012 report of fledged young in Faribault County (Minnesota Ornithologists’ Union 2016). Locational information was not detailed enough to ascribe these records to specific atlas blocks.
Atlas data were used to generate a model to predict the probability of encountering the species across the state (Figure 4). The result accurately depicts the sparse distribution of the species throughout all but the most densely forested regions of northeastern and north-central Minnesota where it is rare to absent. It also predicts that the Tallgrass Aspen Parklands Province and the Prairie Coteau of southwestern Minnesota support the highest breeding densities in the state. Elliot (2016) developed a similar predictive model for the Grasshopper Sparrow in southwestern Minnesota. The result is quite similar to that depicted by MNBBA data in Figure 4 in the southwest region.
Overall, the Grasshopper Sparrow’s distribution appears to have changed very little in the past 100 years in Minnesota. Forest clearing has likely provided more habitat opportunities for the species in the western and southern regions of the Laurentian Mixed Forest Province, but it still remains a sparsely distributed species there and elsewhere throughout the state.
Loss of grassland habitat throughout the sparrow’s breeding range has led to major population declines. In many eastern regions the species is present only in small remnant populations (Vickery 1996). In Wisconsin the species is locally distributed throughout the southern two-thirds of the state; their first atlas confirmed its “spotty and local distribution” (Cutright et al. 2006). Neither Iowa nor South Dakota, states that have completed two atlases (Drilling 2011; Iowa Ornithologist’ Union 2017), documented major changes in the species’ distribution or abundance between the two atlas efforts, despite significant declines in abundance in both states documented by the federal Breeding Bird Survey (BBS) (Sauer et al. 2017).
*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.