- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding resident and migrant, the Lark Sparrow was an uncommon species during the Minnesota Breeding Bird Atlas (MNBBA).
The Lark Sparrow is primarily a species of the western United States, with populations spread across the Great Plains and west to eastern Washington, Oregon, and the California coast, where the species is a year-round resident. Small numbers breed in the southern Prairie Parklands of central Canada and occasionally as far east as Ohio and eastern Tennessee. Year-round populations also occur in Texas and northern Mexico. The species reaches its highest breeding densities in the Great Plains, from Montana south through Texas (Figure 1).
Assigned a Continental Concern Score of 10/20 by Partners in Flight; officially listed as a Special Concern Species in Minnesota and designated a Species in Greatest Conservation Need by the Minnesota Department of Natural Resources.
A short- to medium-distance migrant that winters primarily from Texas south through Mexico and portions of Central America.
A ground-foraging omnivore that feeds primarily on seeds and arthropods. Even during the breeding season birds are frequently seen foraging in small flocks.
An open-cup nest, often placed in a small depression on the ground, frequently located at the base of a small forb or woody plant. Occasionally placed in trees or shrubs less than 4 m high. May reuse its nests or those of other species.
In the late 1800s and early 1900s, Roberts (1932) described the Lark Sparrow as a summer resident in the southern and western regions of Minnesota south of the Laurentian Mixed Forest Province. It was most common in southeastern Minnesota, gradually decreasing in abundance further north through the Red River valley. Confirmed nesting records (nests with eggs) were available from Goodhue, Hennepin, Marshall, and Sherburne Counties; inferred nesting reports (fledglings or adults carrying food) were available from Isanti and Norman Counties.
It is one of Minnesota’s most distinctive sparrows, but Roberts expressed concern that many “bird-students” may have little chance of ever encountering the species:
… unfortunately it is one of the birds that has suffered the greatest diminution in numbers during the last score or so of years. The explanation of this decrease is not evident, but the fact remains that there is not one pair today where there were many twenty-five or thirty years ago.
The rapid loss of the species’ preferred savanna-like habitat was the most likely cause for the decline.
Hibbard commented on the distribution and abundance of many grassland sparrows in Minnesota and North Dakota, including the Lark Sparrow (Hibbard 1965). Lamenting that much of the suitable sandy savanna habitat where the species was found in Sherburne County was being rapidly converted to pine plantations, he urged that the few remaining prairie sites in the Sand Dunes State Forest be protected from such actions.
Ten years later, Green and Janssen (1975) described the Lark Sparrow’s distribution as largely confined to southeastern and east-central Minnesota, as well as the far northwestern corner of the state. Although there were scattered summer reports from west-central and southwestern Minnesota, including Renville and Jackson Counties, these regions lacked breeding records. Indeed, the compiler of the 1975 summer seasonal report, Kim Eckert, commented that the “the range of this species continues to defy description,” as he tried to reconcile just four seasonal reports from widely scattered counties (Eckert 1976).
A few years later, Janssen (1987) delineated four “somewhat separate” breeding areas for the Lark Sparrow: (1) southeastern Minnesota, (2) east-central and central Minnesota north to Washington and Sherburne Counties, (3) the Minnesota River valley west to Chippewa and Yellow Medicine Counties, and (4) northwestern Minnesota from Clay County north to the Canadian border. He identified 8 counties where nesting had been confirmed since 1970: Anoka, Clay, Dakota, Houston, Le Sueur, Polk, Renville, and Wabasha. Hertzel and Janssen (1998) added Otter Tail and Yellow Medicine Counties to this list.
The Minnesota Biological Survey has documented a total of 61 breeding season locations. The majority of records were found in the same regions identified by Janssen (1987). A few records, however, were found between what he delineated as the northwestern population and the east-central population, including records in Becker, Crow Wing, Otter Tail, and Pope Counties. One record was located in Faribault County in south-central Minnesota (Minnesota Department of Natural Resources 2016).
During the MNBBA, participants reported a total of 265 Lark Sparrow records in 3.4% (159/4,738) of the surveyed atlas blocks and in 4.4% (103/2,337) of the priority blocks. Breeding evidence was documented in 53 atlas blocks (Figures 2 and 3; Table 1). The birds were observed in 51 of Minnesota’s 87 counties (5 blocks in the Minnesota River valley straddled 2 counties each) and were confirmed nesting in 24 counties (2 counties, Scott and Chippewa, were included because of blocks that crossed county lines). Seventeen of the counties were additions to the list published by Hertzel and Janssen in 1998.
The Lark Sparrow was largely absent from the densely forested counties of northern Minnesota, with the exception of the sandy jack pine communities in the Brainerd Lakes region. There were two other notable exceptions: one observed record of a bird seen by several individuals in Duluth on July 21, 2012, and one observed record in northern Cook County, reported by Bob Russell on June 23, 2009. The latter record was particularly interesting: three singing males were reported along a section of the Old Gunflint Trail that was burned during the 2007 Ham Lake Fire. Russell, an excellent ornithologist, reported that the site consisted of 40 ha or more of deciduous shrubs and some coniferous growth, “ideal habitat” for the species despite being located nearly 150 miles north of its traditional breeding range in the state. He later noted that the spring of 2009 was a “big year for vagrant Lark Sparrows” in northern Minnesota and Wisconsin, the birds being reported at sites outside of their normal breeding range (Russell pers. comm.). Unfortunately, another excellent birder, Karl Bardon, visited the Gunflint Trail site two days later and could not relocate the birds. Because the Lark Sparrow is an uncommon breeder in southern Manitoba, Russell speculated that the Gunflint Trail birds may have originated from that breeding population.
In addition to the population center in the Brainerd Lakes region, MNBBA records documented that Sherburne County, as well as habitats in adjacent Isanti and Anoka Counties, remained a stronghold for the species. All of these populations are located within two prominent ecological subsections (the Pine Moraines and Outwash Plains Subsection and the Anoka Sand Plain Subsection), characterized in large part by the prominence of sandy outwash plains. Dry prairies, oaks, and jack pines grow in open, savanna-like communities on these soils, which provide ideal habitat for the Lark Sparrow. Elsewhere, the birds were most common in Dakota and Goodhue Counties and along the entire length of the Minnesota River valley, where dry, sandy river terraces and granite outcrops provide ideal habitat. The gravel beach ridges of former Glacial Lake Agassiz in northwestern Minnesota, from Wilkin County north to Polk County, also provide suitable habitat for the species.
When factors other than soils are examined to predict landcover suitability for the Lark Sparrow, including climate, habitat, and landscape context, the resulting model predicts that southeastern Minnesota provides the most extensive region of suitable habitat (Figure 4). Other important areas include the Minnesota River valley, the glacial Lake Agassiz beach ridges in northwestern Minnesota, the lower St. Croix River valley, and the Anoka Sandplain Subsection north of the Twin Cities.
It is difficult to assess the degree to which the Lark Sparrow has changed in distribution and abundance in the past one hundred years. The few locations where Roberts (1932) specifically mentions population declines in his account, including the cities of Minneapolis and Red Wing and the bluffs of the Minnesota River valley, have largely been developed as the Twin Cities metropolitan area and smaller communities have expanded. Of these areas, only the Minnesota River valley still provides suitable habitat. It is unclear if Roberts simply witnessed localized declines due to habitat loss or if the declines were more widespread.
Clearing of the eastern deciduous forest in the late 1800s and early 1900s favored the Lark Sparrow and enabled it to expand east. It wasn’t until the mid-1900s, when urbanization continued and agricultural practices intensified, that the species actually retreated from its initial eastward expansion (Martin and Parrish 2000). In western Wisconsin, the Lark Sparrow declined in abundance during the first half of the twentieth century along the lower Chippewa River. Today it remains localized in abundance and restricted to the west-central and southwestern regions of the state (Cutright et al. 2006). In Ohio, where state officials have classified the species as endangered, the species had become rare and localized by the 1960s and remains so today (Rodewald et al. 2016). In South Dakota, however, detections increased significantly between the state’s first and second atlas, with most of the increase occurring east of the Missouri River (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.