Red-shouldered Hawk

A breeding resident, migrant, and a winter vagrant in southern Minnesota. The Red-shouldered Hawk was uncommon during the Minnesota Breeding Bird Atlas (MNBBA).

Two widely distributed but disjunct breeding populations. One is in the eastern United States as far north as Minnesota and northeast to Maine, and to Quebec, Canada. The second is in California and north to Oregon. Highest breeding densities are in Florida (Figure 1).

Assigned a Continental Concern Score of 8/20 by Partners in Flight. This species is officially listed as a Special Concern Species and a Species in Greatest Conservation Need by the Minnesota Department of Natural Resources.

Eastern populations are short-distance migrants in the eastern United States as far south as Mexico, while Pacific coast populations are permanent residents.

Hunts from an elevated perch for small mammals, amphibians, reptiles, small birds, and insects.

A stick nest in the crotch of a large deciduous tree or sometimes a coniferous tree.

Historically, the Red-shouldered Hawk was apparently a rare bird species in Minnesota. Roberts (1932) apologized that “during fifty-odd years of bird work in Minnesota the writer has never seen the Red-shouldered Hawk alive, though it has been constantly looked for.” Roberts stated the species was an “uncommon resident” and that it “undoubtedly breeds in the south-eastern part of the state.”

Roberts devoted considerable text to purported observations of this species in the late 1800s and early 1900s but dismisses them as errors or mistakes in identification. For example, Currier stated he saw one on June 8, 1902, and several between May 22 and June 8, 1903, near Walker in Cass County (Currier 1904, 34). Roberts also reported an observation by Surber near the Iowa border on September 22, 1920. Roberts’s first observation was of a wing and tail brought to him in September 1922 by Frank Blair, a former superintendent of the State Game Farm near Mound in Hennepin County. The bird had apparently been shot at the farm. Later, he also accepted an observation by young “Mr. Walter Breckenridge who reported seeing one just above Marine on the St. Croix River, Washington County, on July 3, 1927.” He was willing to accept this observation because Breckenridge was from Iowa and familiar with the species. Subsequently, in later years, additional observations were made in the same area, which suggested a nesting pair. Breckenridge would later go on to be a well-respected professor and director of the Bell Museum at the University of Minnesota.

In Roberts’s revised treatise on the birds of Minnesota (1936), he reported the first confirmed nest with 3 eggs that he found in Wayzata, Hennepin County, on April 22, 1934. The nest was one used the previous year by a Cooper’s Hawk. He also reported a nest with 3 eggs found by Nestor Heimenz in 1935 from St. Cloud in Stearns County. He concluded that the Red-shouldered Hawk should be regarded as “not an uncommon bird in the southeastern part of the state, and occasional farther north and west. All the records indicated that this species is undoubtedly extending its range northward and westward.”

By 1975, Green and Janssen described the breeding distribution of the Red-shouldered Hawk as including southeastern Minnesota and extending to as far north as Deerwood and Brainerd in Crow Wing County. Observations during the breeding season extended north to Leech Lake in Cass County, northwest to Tamarac National Wildlife Refuge, and south to Swan Lake in Nicollet County. Green and Janssen reported confirmed nesting in 9 counties, ranging from Olmsted to Crow Wing, and inferred nesting from 5 counties, all in southeastern Minnesota.

A few years later, Johnson (1982) documented 39 nests of the Red-shouldered Hawk from 1970 to 1981, including northwest to Otter Tail and Hubbard Counties. He also stated that observations had been made west to Lac qui Parle County, northwest to Beltrami County, and northeast to Aitkin and Pine Counties. In contrast to the range extensions that had been reported beginning in the 1930s, Johnson (1982) felt “the species is having problems in Minnesota.” Janssen (1987), however, suggested the Red-shouldered Hawk was “expanding northwestward in the state,” noting breeding records as far northwest as Mahnomen County and northeast to Aitkin and Pine Counties. He included confirmed nesting from 11 counties since 1970. Hertzel and Janssen (1998) expanded the list to 18 counties with confirmed nesting records since 1970 but generally within the same breeding distribution described by Johnson (1982) and Janssen (1987).

In 2004, Stucker et al. provided a review on the status of the Red-shouldered Hawk in Minnesota. They used reports from the Minnesota County Biological Survey (MBS), the Minnesota Department of Natural Resources Rare Features database, and other observations and reported a total 460 Red-shouldered Hawk locations statewide among 39 counties, primarily in southeastern, east-central, and north-central Minnesota. They also included 3 locations in northeastern Minnesota, 2 in southeastern St. Louis County and 1 in eastern Cook County. They stated that these records were well beyond the previously known breeding range and their significance is unclear but acknowledged that the species may nest at low densities at these locations and perhaps at other locations in northeastern Minnesota.

The Minnesota Biological Survey (MBS) recorded 334 breeding season locations of the Red-shouldered Hawk (Minnesota Department of Natural Resources 2017a). Their intensive surveys, which began in the late 1980s, revealed a substantial number of locations in west-central Minnesota, especially in the Hardwood Hills Subsection, the northwestern area of Morrison County (e.g., Camp Ripley Training Center), and along the Crow Wing, Mississippi, and St. Croix River floodplains.

The participants of the MNBBA documented 251 records of the Red-shouldered Hawk with a pattern of distribution similar to what had been previously reported (Figure 2). These records showed a strong pattern from the southeast in Houston County, northwest to Norman and Polk Counties, and northeast to Itasca and Carlton Counties. Breeding evidence was recorded in 4.0% (188/4,742) of all surveyed blocks and 4.2% (98/2,337) of priority blocks (Figure 3; Table 1). Nesting was confirmed in 43 blocks within 18 counties. The relatively low ratio of confirmed nesting compared with probable and possible nesting (43/131 or 1:3) likely reflects the secretive behavior of this species once nesting has begun (Dykstra et al. 2008).

The Red-shouldered Hawk’s breeding distribution had a strong association with the Eastern Broadleaf Forest Province and the southern portion of the Laurentian Mixed Forest Province. All of these records were highly associated with riparian areas of river, lake, and wetland ecosystems within the mixed deciduous-coniferous forests and, as previously noted, along the Mississippi, St. Croix, and Crow Wing Rivers and their tributaries. Detections were also high in the Twin Cities and Brainerd areas, where river floodplains exist but also where coverage was intensive.

In their review of the Red-shouldered Hawk in North America, Dykstra et al. (2008) mentioned little about distributional changes in the northern portions of its eastern population, except for reported range expansions northward in Michigan. Robbins (1991) thought that Red-shouldered Hawks were probably never common in Wisconsin. He pointed out that observations of this species in the mid-1800s were probably misidentifications with the more common Broad-winged Hawk. Early reports by Kumlien and Hollister (1903) said it was by no means a common bird. Cutright et al. (2006) during their breeding bird atlas from 1995–2000 found that the species was widespread but uncommon throughout Wisconsin.

In summary, the observations of Red-shouldered Hawks in northwestern Minnesota reported by Janssen (1987) and the extensive documentations by the MBS and the MNBBA in north-central Minnesota in comparison with those of Roberts (1932, 1936) and Green and Janssen (1975) suggest a range expansion in Minnesota beginning around the 1930s. Even though Currier’s observations in 1902 and 1903 were from central Minnesota in Cass County, many of the previous reports have emphasized that the species has never been numerous and could have been missed early in the 20th century. Johnson (1982) questioned this supposition because he felt that the species’ extensive calling in early spring and summer render it difficult to overlook.

*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.

The Red-shouldered Hawk is broadly described as nesting in bottomland hardwoods, riparian areas, flooded deciduous swamps, large woodlots, and suburban areas (Dykstra et al. 2008). Stucker et al. (2004) emphasized the species use of upland deciduous forests, particularly in the central and north-central regions of the state and especially the importance of wetland openings within and adjacent to forest habitats. However, they also found one-quarter of their extensive records of the species were from lowland forests such as those dominated by silver maple floodplains and to a lesser extent in green and black ash forests. Detailed studies in Cass and Morrison Counties by Henneman (2006) and Henneman and Andersen (2009) found Red-shouldered Hawks in large, mature deciduous forests without openings but also in mature deciduous forests with small forest openings from timber harvest (<5 ha). Many of these habitat characteristics were also summarized by the Minnesota Department of Natural Resources (2017b) (Figure 4).

Red-shouldered Hawk nest sites are generally in mature northern hardwood forests, and they use many species of deciduous trees and sometimes coniferous trees (Dykstra et al. 2008). Belleman (1998) found 38 nests in the Camp Ripley Military Reservation in central Minnesota. Nest trees were primarily in aspen (61%), oak (34%), and birch (5%) and their average age was 60 years in aspen and 67 years in oak. McLeod et al. (2000) found 58 nests primarily high in mature upland hardwood stands with thick canopies and large-diameter trees in central Minnesota.

The effects of forest fragmentation on Red-shouldered Hawks is equivocal. In Iowa, Bednarz and Dinsmore (1982) found that this species inhabits large woodlots closer to water and far from roads and buildings. They suggested that suitable breeding habitats should be greater than 100 ha in size. Henneman and Andersen (2009) in central Minnesota suggested that landscape context is an important consideration for Red-shouldered Hawks. Large, non-forested areas were detrimental to their populations, but small forest openings less than 5 ha may not affect their occupancy. Stucker et al. (2004) in southeastern Minnesota emphasized the importance of floodplain forests along major rivers for the Red-shouldered Hawk and, in central Minnesota, the need to manage large tracts of forests. The relatively large number of confirmed nests in Twin Cities suburbs found by the MNBBA indicated a tolerance for human disturbance (North and Faber 2014), but this number may also have been influenced by the extensive volunteer efforts in that region. Dykstra et al. (2008) reported that home ranges ranged in size from 90 to 200 ha.

Partners in Flight recently estimated a United States and Canadian population of 1.1 million breeding adults and 1,100 in the state of Minnesota (Partners in Flight 2017). The species was too rare on point counts used in the MNBBA to adequately estimate a population in Minnesota. Farmer et al. (2008) estimated the population to be much lower than Partners in Flight’s number, ranging from 10,000 to 100,000 based on raptor migration count sites. However, because Partners in Flight also estimated a greater than 200% increase in the species’ population from 1970 to 2014, the discrepancy between these two estimates may partly be due to the differences in time.

Population trend estimates can be difficult to determine for this species. The trends estimated from the federal Breeding Bird Survey (BBS) were unreliable for Minnesota because the mean number of birds detected per route per year was substantially less than 1. The most reliable regional estimate was from the Southeastern Coastal Plain region in the southeastern United States. Based on 290 BBS routes, the population increased 2.53% per year from 1966 to 2015 (Figure 5). In this region, trends were based on a mean of 1.05 detections per route per year.

Farmer et al. (2008) reported that the number of Red-shouldered Hawks on Christmas Bird Counts in the eastern and southeastern United States had significantly increased from 1974 to 2004. The Raptor Population Index from sites with enough observations in the eastern United States showed a mixed pattern of some migration count sites with increases and others with decreases (Farmer et al. 2008).

McLeod and Andersen (1998) noted a high density of 1 nest per km² at the Camp Ripley Training Center in central Minnesota, but estimates in other locations summarized by Dykstra et al. (2008) were much lower and ranged from 0.03 to 0.15 nests per km².

The Red-shouldered Hawk was listed as a Special Concern Species in 1984 (Minnesota Department of Natural Resources 2017b) and as a Species in Greatest Conservation Need by the Minnesota Department of Natural Resources (2015). The former listing was because migration counts had indicated a slow decline in the north-central United States. This was likely due to problems with DDT exposure as well as habitat loss and fragmentation. The most recent designation also reflects concerns with habitat degradation and fragmentation and with its requirement of a large home range. The Partners in Flight (2017) Continental Concern score of 8/20 reflects a relatively low conservation concern for this species, especially since its population has been increasing.

In the early 20th century the species was shot, but legal protection and educational programs have reduced this source of mortality. The species was affected by DDT but less severely in comparison with other raptors. The overall effect of these combined factors on Red-shouldered Hawk populations is unknown.

Cutting of large contiguous forest tracts and fragmentation of breeding habitats into small blocks of forest for agriculture or urbanization have been documented to reduce populations (Dykstra et al. 2008). These changes reduce effective nesting and foraging areas for Red-shouldered Hawks. As forests are fragmented into smaller units, they become more suitable for both the Red-tailed Hawk, its closest competitor, and the Great Horned Owl, one of its nest predators.

Following the 1984 listing of the Red-shouldered Hawk in Minnesota, the Minnesota Department of Natural Resources (2017b) initiated a number of studies of the species. Among its management recommendations were retaining large amounts of mature deciduous forest, using thinning and light-selection cuts in forest cuts within these forest types, protecting wetland openings that are used for foraging, and maintaining a canopy closure of greater than 70%. The species is sensitive to human disturbance. Activity within 300 m of nest sites should be minimized during the breeding season of April 1 to June 30. Finally, maintaining previous nest sites is encouraged because Red-shouldered Hawks will reuse their nests.

The species has not been listed as a concern relative to climate change, primarily because of its extensive distribution in southern regions and its opportunity to colonize available habitat northward.