- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular summer breeding resident and migrant; regularly observed in the winter months, especially in southern Minnesota. The Northern Harrier was a common species during the Minnesota Breeding Bird Atlas (MNBBA).
Distributed across Canada, the northern United States, and the western United States south to southern California, northern New Mexico, and northern Texas. The species is most abundant in the northern Great Plains of the United States and the central Canadian provinces (Figure 1).
Assigned a Continental Concern Score of 11/20 by Partners in Flight; designated a Species in Greatest Conservation Need in Minnesota.
Partial to long-distance migrant; northern breeding populations are believed to winter farther south than populations that breed farther south. Some birds are present year-round in Minnesota, but it is unknown if these are northern migrants or overwintering summer residents.
Plunges from low flight to capture prey on the ground; food consists primarily of small mammals and small birds.
A small depression or platform constructed of grasses and forbs; nests are located on the ground in an upland field or over very shallow water at the edge of a wetland.
In the late 1800s, Hatch (1892) considered the Northern Harrier, or Marsh Hawk as it was then known, as “undeniably the most abundant of the hawks that visit the state.” Forty years later, Roberts (1932) commented that although numbers were reduced, it remained abundant. It was often the only hawk seen during extensive forays across the state, particularly in the open country of western and central Minnesota. At the time, confirmed nesting records (nests with eggs or young) were available from 12 counties stretching from Jackson and Lincoln Counties in the southwest, east to the Twin Cities, and northwest to Marshall County.
As descriptions did of so many hawks, early accounts of the “Marsh Hawk” focused on its feeding habits and whether the species was considered beneficial to the farmer. Most naturalists and ornithologists of the late 19th and early 20th century classified it as a beneficial species; its diet consisted principally of field rodents and small birds (Bent 1937; Roberts 1932). Although the species was not entirely immune to the wrath that many farmers had for all hawks, Roberts wrote that “it survived the warfare better than any other species.”
When Green and Janssen (1975) prepared an updated account of the species’ status, the Northern Harrier was considered to be one of the three most common raptors in the state; the other two were the Red-tailed Hawk and the American Kestrel. Farther north the Northern Harrier was found in small marshes, wet meadows, and peatlands that dotted the forest landscape but was outnumbered by many forest-dependent species. Despite its being a relatively abundant species, there was evidence of recent declines due to the loss of wetland habitats.
In 1982, Johnson prepared a comprehensive summary of the status of all raptors nesting in Minnesota. He noted a total of 61 nest records for the species from 1880 to 1981; only 16 of these records were since 1960. In addition, from 1970 to 1981 there were no observations of Northern Harriers from 16 counties where they had been observed or reported nesting prior to 1970. Johnson acknowledged the lack of observers actively searching for nests might contribute to the smaller number of records. Nonetheless, he believed the decline in records was more likely an accurate reflection of a true population decline due to the “tremendous loss of habitat.”
In 1987, Janssen commented that the Northern Harrier had virtually disappeared from southern Minnesota but remained common in the northwest and north-central regions. He delineated 13 counties where nesting had been confirmed since 1970; all were located north of the Minnesota River valley (Janssen 1987). By 1998, it appeared that the species might be increasing in numbers and reoccupying portions of its former range, as Hertzel and Janssen (1998) identified 17 counties where nesting had been confirmed since 1970. One county (Mahnomen) identified by Janssen (1987) was no longer listed, but the 5 new counties added were all south of the Minnesota River (Lac qui Parle, Jackson, Nobles, Rice, and Wabasha).
Beginning in the late 1980s, field biologists with the Minnesota Biological Survey tallied a total of 473 breeding season locations for the Northern Harrier. The reports were well distributed across the state, from Rock County east to Winona County, and north to Kittson and Cook Counties. Included were numerous observations in southwestern Minnesota (Minnesota Department of Natural Resources 2016).
During the MNBBA, observers reported 1,417 Northern Harrier records in 21.9% (1,048/4,780) of the surveyed atlas blocks and in 27.3% (639/2,337) of the priority blocks. Breeding was confirmed in 1.1% (54) of the surveyed blocks (Figures 2 and 3; Table 1). The bird was observed in all but 1 (Watonwan) of Minnesota’s 87 counties, and breeding evidence was gathered in 35 counties, which were well dispersed across all regions of the state. At least 26 of the 35 counties were additions to the list published by Hertzel and Janssen in 1998.
Incorporating MNBBA data, the landcover suitability map for the Northern Harrier predicts that suitable habitat is found in nearly all regions of the state with the exception of the Twin Cities and much of northeastern and far north-central Minnesota (Figure 4). Northwestern Minnesota provides the most suitable habitat, and there are scattered pockets throughout the central and southwestern regions as well. The block of highly suitable habitat in Anoka County is the Carlos Avery Wildlife Management Area.
Clearly the Northern Harrier is faring better than records suggested in the mid- to late 1900s and has reoccupied its former range south of the Minnesota River valley. It remains most abundant, however, in the Prairie Parkland and Tallgrass Aspen Parklands Provinces of western Minnesota, and in central Minnesota south and west of Duluth. Although records are sparse in the north-central, northeastern, and southeastern regions of the state, Northern Harriers occur in these regions as well.
Despite its relatively broad distribution in the state, it is doubtful that the Northern Harrier has recovered to the former levels of abundance implied by Roberts in the early 1900s. And who would have imagined 40 years ago that the species would eventually become less abundant than the Bald Eagle! Not only is the harrier no longer one of the three most abundant raptors in Minnesota, but there were 50% more MNBBA records tallied for the eagle (2,113) than for the harrier (1,417). Among all raptors, the Northern Harrier fell to fifth place behind the Red-tailed Hawk, the Bald Eagle, the Turkey Vulture, and the American Kestrel.
To the east, in Wisconsin, the Northern Harrier was found to be common throughout most of the state during its first atlas. Its distribution had changed little since the late 1980s (Cutright et al. 2006). To the south, in Iowa, Northern Harriers were found in twice as many blocks during its second atlas (2008–2012) as they were during its first atlas approximately 20 years earlier (1985–1990) (Iowa Ornithologists’ Union 2017).
*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.