- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding resident and migrant, occasionally reported during the winter months. The Savannah Sparrow was an abundant species during the Minnesota Breeding Bird Atlas (MNBBA).
Breeding range spans from Alaska east across all of Canada, south through the Pacific Northwest and northern California, and east across the northern Great Plains, the Great Lakes, New England, and the Appalachian Mountains. Resident populations are present in southern California, Baja California, and central Mexico. Populations reach their highest breeding densities in the northern Great Plains of the United States and in Canada’s Prairie Provinces (Figure 1).
Assigned a Continental Concern Score of 8/20 by Partners in Flight.
A short- to medium-distance migrant that winters in the southern United States and Central America.
An omnivorous ground forager that feeds on a variety of seeds and insects.
An open-cup nest placed in a shallow depression on the ground, usually tucked within a mound of vegetation or well-hidden by a canopy of forbs and grasses. A small tunnel underneath the grasses may lead to the nest.
In the late 1800s and early 1900s, Roberts (1932) described the Savannah Sparrow as a common breeding resident throughout Minnesota wherever suitable habitats were present. This diminutive sparrow, with its distinctive buzzy song, was abundant “on the western prairies, where it inhabits not only the lowlands but also upland thickets of rose-bushes, hazel, and wolfberry.” It was found in northern Minnesota, where it was “confined to meadows adjoining lakes and marshy land and to old grass-grown clearings.” Despite its abundance and widespread distribution, confirmed nesting records (nest with eggs or young) were few and were confined primarily to western and east-central Minnesota: Grant, Hennepin, Kittson, Otter Tail, Pennington, Polk, Ramsey, and Wilkin Counties. An inferred nesting record (fledged young) was available from Itasca County.
A widespread, abundant, and complex species, the Savannah Sparrow displays considerable morphological variation across its range. The most variable trait is the darkness of the plumage. Indeed, taxonomists have debated the delineation of different species and subspecies for years. Roberts (1932) sent a series of 32 specimens collected in Minnesota to the U.S. Biological Survey for examination. All but one were identified as belonging to the eastern subspecies, Passerculus sandwichensis savanna, although their plumage appeared intermediate between the lighter western subspecies, P. s. alaudinus, and the darker eastern subspecies. Five specimens collected in the late 1800s in Pembina, North Dakota, were all identified as belonging to the western subspecies. Today, a total of 17 subspecies are recognized, and Rising (2010) has recently proposed that these be collapsed into four distinct species. Minnesota birds would remain as the nominate species, Passerculus sandwichensis.
Decades after Roberts’s observations, both Green and Janssen (1975) and Janssen (1987) noted that the species was a breeding resident throughout Minnesota wherever “low-lying grassy fields” were present. Janssen included a statewide distribution map that identified 13 counties where nesting had been confirmed since 1970. Long considered a species of the western grasslands, intensive field surveys in Minnesota’s peatlands in the 1980s revealed that the Savannah Sparrow was very common in open, unforested peatlands. It dominated the avifauna associated with the “matted sedge and heath vegetation of the ombrotrophic peatlands” (Niemi and Hanowski 1992).
The species’ statewide distribution was further confirmed by the Minnesota Biological Survey (Minnesota Department of Natural Resources 2016). Beginning in the late 1980s, Minnesota Biological Survey field staff reported a total of 1,465 breeding season locations from all corners of the state. By 1998, Hertzel and Janssen had documented 21 counties where nesting had been confirmed since 1970.
MNBBA participants reported a total of 4,012 Savannah Sparrow records from 45.7% (2,189/4,789) of the surveyed atlas blocks and from 62.8% (1,469/2,338) of the priority blocks. Breeding was confirmed in 166 blocks (Figures 2 and 3; Table 1). Although the species was least abundant in the far northern reaches of the state, it was reported from all 87 Minnesota counties. Breeding evidence was collected from 53 counties.
Probable and confirmed Savannah Sparrow records were especially common in the northwest corner of the state. This is the same region where the MNBBA predicted distribution map predicts the highest breeding densities to occur, as well as across a relatively narrow band in central Minnesota that stretches from Chisago and Pine Counties west to Pope, Douglas, Otter Tail, and southern Becker Counties (Figure 4). Moderately abundant throughout the western, central, and southeastern regions, Savannah Sparrow breeding densities are predicted to be lowest in northeastern and north-central Minnesota, especially the far eastern Arrowhead counties of Cook and Lake, and in the Twin Cities metropolitan region. The importance of peatlands to the species is further evidenced by the relatively high breeding densities predicted in portions of the Agassiz Lowlands Subsection.
Knowledge regarding the range of habitats used by the Savannah Sparrow in Minnesota has grown, but the species’ overall distribution appears relatively unchanged since Roberts (1932) described it as a common summer resident in the early 1900s. In their comprehensive review of the species, Wheelwright and Rising (2008) noted only two historical changes to its distribution: its extirpation from northwestern Arkansas and the apparent extirpation or major decline of a population that breeds in the southwest, in the riparian marshes at the mouth of the Colorado River.
In the north-central United States, few minor changes in distribution have been noted over the years. The species was rare in Ohio in the early 1900s but was widespread throughout the state by the 1930s (Rodewald et al. 2016). Historic accounts in Michigan reported that the sparrow was local and uncommon in the southern Lower Peninsula but was widespread by the 1970s (Chartier et al. 2013). In Wisconsin, the Savannah Sparrow has always been widespread and abundant in all but the most densely forested and densely populated regions (Cutright et al. 2006). South Dakota’s population, however, has been increasing, with a notable range expansion in the northwest (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.