- Minnesota Breeding Bird Distribution
- Breeding Habitat
- Population Abundance
- Literature Cited
A regular breeding species and migrant. The Cliff Swallow was a common species during the Minnesota Breeding Bird Atlas (MNBBA).
Widely distributed across North America, the Cliff Swallow’s breeding distribution ranges across most of Canada and the United States with the exception of the southeastern coastal regions of the United States. It is common throughout its breeding range, reaching its highest densities in mid-America, from the Prairie Pothole Region south to the Texas Gulf coast, and along the Pacific coast from southern Oregon through central California (Figure 1).
Assigned a Continental Concern Score of 6/20 by Partners in Flight.
- A long-distance migrant that winters in South America.
Elaborate gourd-like structure constructed with mud and attached to a vertical surface, an overhanging eave, or another Cliff Swallow nest. Natural surfaces have been replaced largely by bridges, buildings, culverts, and other man-made structures. This social bird nests in colonies that may number from a few hundred to a few thousand nests.
Roberts (1932) provided an interesting account of some of the earliest reports of Cliff Swallows in Minnesota. As early as 1834, explorer G. W. Featherstonhaugh documented the species nesting on granite escarpments along the upper reaches of the Minnesota River. Another observer reported it was abundant along the Blue Earth River about 1848, while Dr. Elliot Coues “found it was so abundant at Fort Pembina on the Red River of the North in 1873 as to be a nuisance” (Roberts 1932). But such early records are few in number, and the species’ true status prior to European settlement is conjectural at best (Robinson and Beer 1955).
In 1932 Roberts wrote that “Until about 1900, the Cliff Swallow was an abundant summer resident, breeding throughout the state, less commonly in the heavily timbered portions.” Breeding evidence (including both confirmed and inferred nesting reports) were available from 11 counties widely dispersed across the state including Fillmore and Wabasha in southeastern Minnesota; Jackson and Renville in western Minnesota; Benton, Hennepin, and Scott in central Minnesota; and Aitkin, Cass, Lake, and Polk in northern Minnesota. The Lake County record was of a small colony nesting at Castle Danger, along the North Shore of Lake Superior. Although natural colony sites were likely common prior to 1850, when European settlers began arriving in large numbers, the swallows found an increasing number of nesting opportunities as the immigrants dotted the state’s landscape with residential buildings and farms. Opportunities expanded even further when roads, highways, bridges, and culverts were added.
Regardless of this rapid expansion in nesting habitat, the species virtually disappeared from the state in the early 1900s. Roberts included a report from an observer in Pipestone in 1921 noting that the swallow “had not been seen in that part of the state for a number of years, though it had formerly been common.” Extensive field excursions through west-central Minnesota in 1924 and 1926 were not successful in locating a single colony (Roberts 1932). Nevertheless, Roberts includes numerous reports from localities across the state, suggesting that the species was slowly recovering beginning in the 1920s.
In their review of the species’ status in the state in 1955, Robinson and Beer discussed the factors most often cited as responsible for the apparent catastrophic decline in the early 1900s, not only in Minnesota but also elsewhere within the central states. Included was the widespread use of paint on old farm buildings, which many thought changed the texture of the surface and prevented the swallows from securing their nests. Other reasons were the deliberate destruction of nests by farmers, and competition with the newly introduced House Sparrow. The authors disputed all three arguments because following the decline, Cliff Swallows increased in abundance despite ever-growing numbers of painted buildings and House Sparrows. Subsequent work confirmed their conclusion that painted barns had little impact on the species (Brown et al. 2017).
Robinson and Beer reviewed all known Cliff Swallow records in the state in an effort to decipher the real cause of the species’ precipitous decline, but there was little evidence to suggest any other possible scenarios. They coupled this review with a mail survey to identify the size and location of known colonies. Although the survey did not provide systematic coverage of the state, it revealed a total of 75 known nesting colonies that were active from 1930 to 1953. With one exception, all the colonies were located on buildings or on the undersides of bridges. The majority of records were from the Twin Cities metropolitan region, southeastern Minnesota, and Duluth. The resulting distribution map more likely reflected where active birders resided then where Cliff Swallows were nesting.
Despite their exhaustive review, in the end Robinson and Beer were left to conclude that all the hypotheses put forth to explain the swallow’s decline “are but speculation and are not based upon detailed observations.” The coincidence of the rapid expansion of the House Sparrow in Minnesota beginning in the late 1800s and the subsequent decline of the Cliff Swallow in the early 1900s does seem compelling. The aggressive House Sparrow is known to usurp Cliff Swallow nests, and local control of House Sparrow populations has been demonstrated to increase Cliff Swallow numbers (Brown et al. 2017). Perhaps, as highway bridges became a more common feature of the landscape, they provided new opportunities for Cliff Swallows that facilitated their subsequent recovery in spite of abundant House Sparrows.
Twenty years later, Green and Janssen (1975) described the Cliff Swallow as a breeding resident throughout the state, least common in the southwestern region and most abundant in the northwestern and northeastern regions. Populations were especially abundant in St. Louis and Marshall Counties. In 1987 Janssen noted that the introduction of corrugated culverts for stream crossings in the agricultural counties had created new nesting opportunities for the species, resulting in even larger nesting populations. He included a statewide distribution map that identified 40 counties where nesting had been confirmed since 1970. Hertzel and Janssen (1998) later added 7 more counties to the list. Dispersed across the state, confirmed nesting records were least abundant south of the Minnesota River.
By the time the Minnesota Biological Survey began field survey work in the late 1980s, Cliff Swallows had become far more abundant and widespread in southern and western Minnesota compared to the central and northeastern regions of the state (Minnesota Department of Natural Resources 2016). To date, a total of 382 breeding season locations have been identified by survey biologists. The vast majority were within the Prairie Parkland Province.
During the MNBBA, observers reported 2,498 Cliff Swallow records from 29.8% (1,437/4,821) of the surveyed atlas blocks and from 39.2% (916/2,337) of the priority blocks. Breeding was documented in 919 blocks (Figures 2 and 3; Table 1). Records were reported and breeding was confirmed in 86 of Minnesota’s 87 counties. Cook County was the only county where Cliff Swallows were not observed. Thirty-nine counties were additions to Hertzel and Janssen’s 1998 published list of counties with confirmed nesting records. Although Cliff Swallows are widely dispersed throughout the state, they are least abundant in the Laurentian Mixed Forest Province.
Whether the Cliff Swallow’s distribution in Minnesota has changed since presettlement times is unclear. There is no doubt, however, that its abundance has increased considerably since the early 1900s, when it was difficult for Roberts and his colleagues to locate a single colony. A similar decline in the early 1900s was not noted in Wisconsin (Cutright et al. 2006) or Michigan (Chartier et al. 2013) but was referenced in recent accounts of the species’ status in both Ontario (Cadman et al. 2007) and Ohio (Rodewald et al. 2016). In Ohio the decline was several decades later, in the 1930s, and was attributed to the growing abundance of House Sparrows.
In their comprehensive review of the species, Brown and his colleagues (2017) discussed its range expansion eastward from the core of its breeding range in western North America. Nearly 200 years ago, in the mid-1800s, noted increases in abundance were observed as settlements grew and spread eastward. Not long afterward, the successful introduction of House Sparrows in 1852 precipitated a decline in Cliff Swallow numbers in the northeastern states as House Sparrows aggressively usurped the swallow nests. Today populations of the Cliff Swallow in the northeastern region of the United States remain relatively small. Farther south, competition with House Sparrows was less problematic, as the Cliff Swallows gradually expanded throughout the mid-Atlantic states, including Tennessee, the Carolinas, Georgia, and Florida. In addition to these expansions, populations also are increasing in abundance throughout the Great Plains (Brown et al. 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.