- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular summer resident and migrant; regular statewide during the winter. The Common Grackle was an abundant species during the Minnesota Breeding Bird Atlas (MNBBA).
Distributed across the eastern two-thirds of North America, the Common Grackle reaches its highest breeding densities in the northern Great Plains, including southwestern Minnesota, and across the Eastern Tallgrass Prairie, including the states of Illinois, Indiana, and Ohio (Figure 1).
Assigned a Continental Concern Score of 9/20 by Partners in Flight and designated a Common Bird in Steep Decline.
Breeding populations located in the northern states and southern Canada, as well as many western populations, are short-distance migrants that winter in the southern United States; southern populations are year-round residents.
An omnivorous ground forager feeding on insects, invertebrates, small fish, amphibians, reptiles, young birds and eggs, small mammals, fruit, seeds, and waste grain.
An open-cup nest usually located in coniferous trees and shrubs; less commonly found in deciduous trees and shrubs, emergent wetland vegetation, and in crevices and cavities. Often nests colonially.
The handsome and well-adapted Common Grackle has long been a common summer resident of Minnesota’s open woodlands and agricultural landscapes. The conversion of Minnesota’s extensive western grasslands into productive agricultural fields provided the perfect setting for the grackle to exploit its opportunities even further. By June 1926, when Roberts took a trip across southern Minnesota, he found them to be the most abundant bird along the entire route (Roberts 1932):
It was constantly in sight and even at that season was in flocks, sometimes covering several acres when feeding in pastures and fields. Although the Grackle was known to have increased in numbers its great abundance was a surprise.
The Common Grackle had even become a very common bird in cities and parks. Confirmed nesting records (nests with eggs or young; flightless young) were available from 9 counties, including numerous records from Minneapolis in Hennepin County, as well as from Aitkin, Goodhue, and Isanti Counties in the eastern half of the state. Further west, records stretched from Jackson and Pipestone Counties in the southwest, north to Grant, Marshall, and Polk Counties. Although Roberts did not specifically address their abundance in northeastern Minnesota, the species was probably scarce across the region’s extensively forested landscape.
Green and Janssen (1975) would later note its sparse distribution in the northern forested counties but wrote that it was not restricted entirely to agricultural lands or urban areas. They observed that the brushy riparian shorelines of rivers and lakes, often some distance from settled areas, also provided suitable habitat. Janssen (1987) also documented its abundance within windbreaks separating agricultural fields and in cities where conifer plantings were common. He reported a total of 41 counties scattered across the state where nesting had been confirmed since 1970. By 1998, Hertzel and Janssen would report the species had been confirmed nesting in 48 counties. The Minnesota Biological Survey further confirmed its statewide distribution, including numerous breeding season locations found throughout the northeastern Arrowhead region (Minnesota Department of Natural Resources 2016).
During the MNBBA, participants reported 5,841 Common Grackle records in 58.1% (2,802/4,822) of the atlas blocks that were surveyed and in 72.2% (1,688/2,337) of the priority blocks. Breeding was confirmed in 21.3% (1,027) of all blocks surveyed (Figures 2 and 3; Table 1). The birds were reported and confirmed breeding in all 87 counties. With a few exceptions, they were reported from virtually every priority block south of a line that extends from the Fargo–Moorhead region in northwestern Minnesota southeast to the Twin Cities, basically following Interstate 94. Although they were broadly distributed north of this line, occurrences were reported from nearly 50% fewer blocks.
Clearly, the extensive clearing and development that has occurred in Minnesota’s northern forest has provided opportunities for the Common Grackle in the past 100 years. Yet, as the species expanded into northeastern Minnesota, the most significant change in its North American distribution in the twentieth century was its expansion westward. Facilitating this expansion was an increase in the number of shelterbelts, an ideal habitat for the species. As arid lands across the northern and central plains were irrigated and cultivated, shelterbelts became a more common feature across the landscape (Peer and Bollinger 1997). One only needs to encounter the cacophony of sounds emitted by a dense colony of nesting grackles in western Minnesota’s shelterbelts to appreciate the importance of this modified habitat to the birds.
*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.