- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding species and migrant. The Bobolink was common in abundance during the Minnesota Breeding Bird Atlas (MNBBA).
Distributed throughout the north-central and northeastern United States and southern Canada, from southern British Columbia and eastern Washington and Oregon, east to southern Quebec and Newfoundland in the north and western Virginia in the south. The Bobolink is most abundant in the northern Great Plains (Figure 1).
Assigned a Continental Concern Score of 14/20 by Partners in Flight and added to their 2016 Watch List; designated a Species in Greatest Conservation Need by the Minnesota Department of Natural Resources and a Stewardship Species by Audubon Minnesota.
A long-distance, Neotropical migrant undertaking one of the longest migratory trips of any New World songbird to its wintering grounds in South America.
A variety of terrestrial insects, weed seeds, and small grains.
A ground nest usually nestled at the base of grassland forbs.
This stunning blackbird, with its unique plumage and bubbly aerial song is near the northern periphery of its breeding range in Minnesota. Roberts (1932) considered the Bobolink a common summer resident throughout the state “wherever there are suitable lowlands.” Most common in the western grasslands, it also could be found further east in small hayfields and pastures that were embedded across the forested landscape. Confirmed nesting records (nests with eggs or young) were reported from 8 counties including such widely scattered locations as Pipestone County in southwestern Minnesota, north to Marshall County in northwestern Minnesota, and east to Hennepin, Isanti, Mille Lacs, and Scott Counties. At the time, Roberts expressed concern that the Bobolink was declining in abundance and was being replaced by the more aggressive Brewer’s Blackbird. The latter species was rapidly expanding its breeding distribution from the northern Great Plains east across the Great Lakes, New England, and the Maritime Provinces. Both are open habitat species.
Both Green and Janssen (1975) and Janssen (1987) described the Bobolink’s distribution in a manner similar to that of Roberts, pointing out that it was most abundant in the western and northwestern regions of the state and least abundant in the north-central and northeastern regions. Janssen identified 15 counties where nesting had been confirmed since 1970. Hertzel and Janssen (1998) later added six more counties to the list.
As of 2014, the Minnesota Biological Survey (MBS) reported a total of 1,653 breeding season locations. Widespread throughout the Prairie Parklands and Tallgrass Aspen Parklands, a significant number of records also were reported in north-central Minnesota, from Clearwater County east to central St. Louis County, with a particularly high number of reports in Aitkin County (Minnesota Department of Natural Resources 2016).
The MNBBA reported 3,376 breeding records in 37.6% (1,804/4,801) of the surveyed atlas blocks and 50.6% (1,182/2,337) of the priority blocks. Breeding evidence was documented in 148 blocks (Figures 2 and 3; Table 1). The birds were observed in all 87 Minnesota counties, including one record at a farmstead near the North Shore of Lake Superior in Cook County. Breeding evidence was documented in 61 of Minnesota’s 87 counties, including 44 counties that were additions to those delineated by Hertzel and Janssen (1998).
As indicated by earlier accounts, MNBBA records indicate the species is most abundant in the Prairie Parklands and Tallgrass Aspen Parklands Ecological Provinces. It is widely dispersed through the Eastern Broadleaf Forest Province as well, with the exception of the Twin Cities and Rochester metropolitan areas; it remains least abundant in the Laurentian Mixed Forest, especially in Cook and Lake Counties. Despite Roberts’s concern about its status one hundred years ago, the Bobolink remains a common and widely distributed species in Minnesota.
Atlas data were used to develop a model to predict the probability of encountering Bobolinks statewide (Figure 4). The result predicted the core of the species’ breeding distribution is in the Red River valley and the Aspen Parklands of northwestern Minnesota. A narrow band of high densities also stretches across central Minnesota from west-central Minnesota east to Kanabec and western Pine County and south from west-central Minnesota to the Iowa border. Elsewhere outside of the Laurentian Mixed Forest Province the species is common but at moderate breeding densities. Although there are small pockets of abundance predicted throughout the northern forest, Bobolinks are predicted to be rare to absent across the region.
Historically, Bobolinks expanded east as forests were cleared and expanded further west as more arid lands were irrigated and cultivated (Renfrew et al. 2015). Today, as some of these previously cleared areas in the east are abandoned and once again succeed to forest, the Bobolink’s range is receding locally, such as in the Southern Shield of Ontario (Cadman et al. 2007).
*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.