- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding species and migrant throughout the state. The Rose-breasted Grosbeak was abundant during the Minnesota Breeding Bird Atlas (MNBBA).
Distributed primarily in the northeastern and midwestern United States and in Canada as far northwest as northern Alberta. The highest densities are found in the upper midwestern United States, including Michigan, Minnesota, and Wisconsin (Figure 1).
Assigned a Continental Concern of 11/20 by Partners in Flight; identified as a Minnesota Stewardship species by Audubon Minnesota.
Medium- to long-distance migrant over-winters in Mexico and Central America, rarely in southern United States and Cuba.
Omnivorous, consuming invertebrates (especially beetles), fruit, and seeds, gathered in many ways.
Loose open cup in vertical branch or crotch of shrub, sapling, or small tree.
Historically widely distributed across the state, Roberts (1932) described the Rose-breasted Grosbeak as abundant in the southern deciduous forests and less abundant in the north. He also noted the species was common in prairie groves and along lakes and streams. Nesting was confirmed from the late 1800s to 1932 from Crow Wing County (nest with egg and young), Goodhue County (nests with eggs and young), Houston County (nests with egg), Isanti County (nests with eggs and young), Itasca County (nests with eggs), Itasca Park (male feeding young), Minneapolis (nests with eggs and young), Polk County (nests, fresh eggs), Rock County (nest), Stearns County (nest), St. Paul (young nearly full grown) and Wabasha County (nest with young).
Green and Janssen (1975) did not present a confirmed nesting map by county; instead they simply described the species as a “resident throughout the state” and “most numerous in deciduous forests of the central and southern regions.” Janssen (1987) similarly emphasized the breeding distribution throughout the wooded portions of the state. He included confirmed nesting since 1970 from 33 Minnesota counties that range from Nobles County in the southwest to Pennington County in the northwest, to Lake County in the northeast, and Houston County in the far corner of the southeast. Counties with confirmed nesting were concentrated in the southern and central counties, though these areas were also where the highest concentrations of bird observers were located. Hertzel and Janssen (1998) expanded the counties with confirmed nesting to 44, with most in the southern tier and in the south-central counties.
The Minnesota Biological Survey breeding season locations indicated the species was present in every county it has sampled, except from Wilkin County north along the Minnesota–North Dakota border (Minnesota Department of Natural Resources 2016).
The MNBBA clearly illustrates its statewide distribution, with potential nesting in every county of the state (Figure 2). This includes possible nesting in 5 priority blocks in Wilkin County and in all counties bordering North Dakota. Confirmed nesting was reported in 187 blocks, while observed to confirmed nesting was reported from 48.3% (2292/4,746) of all blocks sampled (Figure 3; Table 1). The atlas added confirmed nesting in 27 counties not previously reported since 1970 by Hertzel and Janssen (1998).
Previous descriptions of the Rose-breasted Grosbeak had emphasized that it primarily occurred in the central and southern regions of the state. However, when coverage included the whole state and incorporated climate, habitat, landscape potential, and detectability, the heart of the species’ distribution was predicted to be in the north-central regions and along the major river valleys (Figure 4). This primarily included the ecological provinces of the Laurentian Mixed Forest (particularly the western portions), the northern portions of the Tallgrass Aspen Parklands, and the Eastern Broadleaf Forest. These areas are currently heavily dominated by deciduous forests. In particular, the extreme northwestern counties near the boundary between Kittson and Roseau Counties were predicted to have the highest densities.
The MNBBA results also highlighted a broad and even distribution in the state (Figure 2). The modeled distribution, however, is also supported by recent analysis of the federal Breeding Bird Survey (BBS) (Figure 1). The BBS relative abundance map shows the highest densities of 10–30 detections per route in central and northern Minnesota. This provides further evidence and support for defining breeding distributions based on a solid statistical design, rather than limiting distributions to where the observers are located.
Cutright et al. (2006) describe a statewide distribution in Wisconsin based on their recent breeding bird atlas with confirmed, probable, or possible nesting in about 89% of the 1006 quads sampled. They did not include a probability map, so their results cannot be compared to the MNBBA. The Ontario breeding bird atlas (Cadman 2007), however, did illustrate high relative abundance values for this species in western Ontario (0.9 to 2.6 birds per 25 point counts) along the border with Lake of the Woods to Cook County. The Manitoba Breeding Bird Atlas (Bird Studies Canada 2017) also illustrated strong breeding evidence near the border with Minnesota from Kittson to Lake of the Woods Counties.
Wyatt and Francis (2002) describe many range contractions and extensions in their summary of historical changes in the breeding distribution that have occurred since the late 1800s. In particular, they describe that urbanization and agriculture appear to have produced mixed effects on the species. If the conversion of forests is not too extensive and forest fragments are still present but the canopy is open, then the changes may benefit the species. However, complete clearing without maintaining suitable forest habitat, such as has occurred in a substantial part of southern and western Minnesota, will greatly limit available habitat to a few woodlots or riparian forests along lakes, streams, and rivers. In contrast, the Rose-breasted Grosbeak has adapted to many urban environments where suitable habitat remains and is tolerant of several successional stages following forest cutting, especially after harvesting as the shrub and saplings mature. Fortunately, the species is currently secure in Minnesota. Future distributional changes are unknown until the next systematic breeding bird atlas is completed.
*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.