- Scientific name: Petrochelidon pyrrhonota
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
Description
The cliff swallow is small, pointed-winged, aerial insectivore with a square tail, orange rump, and chestnut-colored throat. They historically nested in large colonies on cliff faces in the western United States but are now found across much of North America, nesting in the east primarily on artificial surfaces such as bridges, culverts, and buildings.
Life cycle and behavior
The cliff swallow’s breeding season begins in May, several weeks after they return from their wintering grounds in South America. They are colonial nesters and require a vertical substrate with a horizontal overhang, such as human-made structures or natural cliffs. Gourd-shaped nests are constructed by both sexes and are composed primarily of mud lined with dry grass. Cliff swallows lay 1-6 light-colored speckled eggs and may have 2 broods. Males and females incubate the eggs for about 10–19 days, and the young fledge in about 20-26 days. Fall migration begins after fledging and as the colony is vacated, typically in July and peaking in the US in August and early September. Cliff swallows overwinter in South America mainly east of the Andes Mountains.
Population status
According to the Breeding Bird Survey (BBS), cliff swallow populations have shown a decreasing trend in Massachusetts as well as a significant decrease in the eastern US. Control of house sparrows has led to increased cliff swallow numbers in some locations. Installations of artificial structures may also assist in increasing or stabilizing populations.
Distribution and abundance
Cliff swallows have been steadily declining as breeders in Massachusetts and are now relegated primarily to small colonies in Berkshire, Franklin, and northern Essex Counties.
In the first Massachusetts Breeding Bird Atlas, the mountainous western areas of the state hosted fair numbers of cliff swallow colonies, both on natural cliffs and on human structures such as barns and bridges. The Connecticut River Valley had no shortage of such structures but had only 21% occupancy by blocks, likely due to heavy infiltration of house sparrows. Swallows were present in similar proportions across the Worcester and Lower Worcester Plateau regions, but coastal plains records were almost entirely restricted to the northern parts of the region. Only a handful of cliff swallow colonies were reported in the lowlands and Cape Cod.
By Atlas 2, no cliff swallows were found in Norfolk, Bristol, Plymouth, Barnstable, or Nantucket Counties. The species entirely vacated the Worcester Plateau as well. The cliff swallows that were found in Massachusetts during Atlas 2 covered less than half the breeding footprint of Atlas I and were largely located in the west, where suitable nesting sites (i.e., old barns) could still be found, along with a few sites in northern Essex County. Today, the numbers of cliff swallow colonies continue to be limited in the state and are primarily located in Berkshire County.
Habitat
Cliff swallows nest in colonies, building their mud nests on the sides of cliff faces, buildings, bridges, and culverts. Colonies are usually associated with open area such as fields and wetlands and are often in the vicinity of open water.
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Threats
Competition for nesting sites by house sparrows is thought to be a primary limiting factor of cliff swallows.
Conservation
Controlling local house sparrow populations is effective in increasing cliff swallow populations. Deploying nesting structures designed for the species and limiting construction projects of bridges and culverts to non-nesting seasons may also be effective conservation measures.
References
Breeding Bird Atlas Explorer (online resource). 2015. U.S. Geological Survey Patuxent Wildlife Research Center. <2015-04-01>. http://www.pwrc.usgs.gov/bba. Data compiled from: Massachusetts Breeding Bird Atlas 2007-2011
Brown, C. R., M. B. Brown, P. Pyle, and M. A. Patten (2020). Cliff Swallow (Petrochelidon pyrrhonota), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.cliswa.01
Sauer, J.R., J.E. Hines, J.E. Fallon, K.L. Pardieck, D.J. Ziolkowski, Jr., and W.A. Link. 2014. The North American Breeding Bird Survey, Results and Analysis 1966 - 2013. Version 01.30.2015 USGS Patuxent Wildlife Research Center, Laurel, MD
Veit, R.R, and W.R. Petersen. 1993. Birds of Massachusetts. Massachusetts Audubon Society, Lincoln MA.
Contact
| Date published: | May 16, 2025 |
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