Cliff swallows are a migratory bird species found throughout much of North America. They are known for building mud nests on vertical surfaces like cliffs, hence their name. Cliff swallows have a very wide range and can be found across much of the United States and Canada during their breeding season. After nesting, they migrate south to spend the winter in South America.
Breeding Range
The cliff swallow’s breeding range extends across most of North America. They can be found across the western United States from the Pacific Coast eastward to the Great Plains. Their range extends northward across western Canada and Alaska. Cliff swallows also breed in the eastern United States from the Great Lakes region east to the Atlantic Coast, as far south as Florida and the Gulf Coast. Some key areas where they nest during the breeding seasons include:
- Pacific Coast – Found along the coast from southern Alaska to Baja California.
- Western Mountains – Abundant in mountainous areas like the Rocky Mountains and Sierra Nevada Range.
- Midwest – Common across the Great Plains and around the Great Lakes region.
- Northeast – Nest in colonies in areas like New York, Vermont, and Maine.
- Southeast – Breed in coastal areas from Texas along the Gulf Coast up to North Carolina.
Cliff swallows often form nesting colonies on cliffs, bluffs, canyon walls, and along the sides of buildings. Their mud nests are clustered together, sometimes with hundreds of nests stacked up together on vertical surfaces. Some prime nesting locations include:
- Cliffs and bluffs – Ideal natural nesting sites with vertical surfaces.
- Canyons – Found along canyon walls in areas like the southwestern United States.
- Bridges – Often nest in large groups underneath bridges.
- Barns – Nest on the vertical walls of old barns and other structures.
- Buildings – Form colonies on walls of buildings, especially in more rural areas.
Wintering Range
Cliff swallows migrate long distances to spend the winter in South America. Their wintering grounds extend across many parts of South America, including:
- Central America – Can be found in Panama, Costa Rica, and as far south as Nicaragua.
- Caribbean Coast – Winters along the northern coasts of South America in Venezuela and Colombia.
- Amazon Basin – Spends winters in areas along the Amazon River in Peru, Brazil, and Bolivia.
- Gran Chaco – Found in the Gran Chaco plain in Paraguay, Bolivia, and Argentina.
- Patagonia – Winters in southern South America in areas like southern Chile and Argentina.
Cliff swallows tend to avoid higher elevation areas in the Andes Mountains. They are widespread across the lower elevations of South America, foraging in open and semi-open habitats like grasslands, agricultural areas, savannas, and wetlands throughout their winter range.
Migration
The cliff swallow undertakes a lengthy migration between its breeding grounds in North American and wintering range in South America. The migration route spans thousands of miles between the regions. Key aspects of the cliff swallow’s migration include:
- Spring Migration – They leave South America in February and March to head north to their breeding sites, arriving in late March to May.
- Fall Migration – The swallows leave their breeding grounds in late July and August, arriving in South America in September to November.
- Travels in Flocks – They migrate together in large flocks that can number in the thousands of birds.
- Stopping Points – Their migration includes stops to rest and feed, like the Platte River in Nebraska where thousands congregate.
- Impressive Distance – One way migrations can be 5,000 miles between nesting sites and wintering grounds.
Some cliff swallows also have shorter migration routines. Populations in the southwestern U.S. and along the Pacific Coast may only migrate relatively short distances. The swallows in Florida and along the Gulf Coast often do not migrate at all and can remain year-round residents in those warmer areas.
Habitat
Cliff swallows nest in areas that provide vertical nesting surfaces, open flying space, and mud for nest construction. They are also found in a variety of habitats during migration and in their wintering grounds. Typical cliff swallow habitats include:
- Cliffs – Nest on rocky cliffs, canyon walls, bluffs, and sea cliffs along the coast.
- Bridges – Find manmade nesting sites under bridges, in culverts, and on structures.
- Buildings – Often nest under the eaves of buildings, on walls, or inside abandoned structures.
- Agricultural Areas – Common around farm buildings. Also forage over croplands and pastures.
- Marshes – Found foraging over wetlands like marshes, swamps, and ponds.
- Grasslands – Utilize open grassland habitats including prairies, savannas, and pasturelands.
Cliff swallows are able to utilize both natural areas and manmade structures as nesting colonies. They thrive in open habitats with a source of mud for their nests, and bodies of water for drinking and bathing. Though found in diverse settings, cliffs and rocky areas remain the preferred natural nesting areas.
Range Maps
These range maps help illustrate the breeding and wintering ranges of the cliff swallow across North and South America:
Breeding Range
Image Source: Cornell Lab of Ornithology
Wintering Range
Image Source: Cornell Lab of Ornithology
Population and Conservation
Cliff swallows remain a common and widespread species, but may face some population declines. Their population and conservation status includes:
- Global population – Estimated between 18-56 million individual birds worldwide.
- Population trend – Believed to be declining but at a relatively slow rate overall.
- Threats – Habitat loss, declining insect prey, climate change, nest site competition from invasive species, and parasites.
- Conservation status
- IUCN Red List – Least Concern
- US Fish & Wildlife Service – Not listed
More research is needed to fully understand cliff swallow population trends over time. Providing suitable nesting sites and habitats helps support their populations. Blocking access to nests, removing colonies, or cleaning nests should be avoided whenever possible.
Conclusion
In summary, cliff swallows have an extensive breeding range across most of North America. They migrate long distances to winter in Central and South America. Cliff swallows rely on vertical nesting surfaces, are often found near water, and thrive in open habitats. They remain common overall but may be facing some population declines from habitat loss and other threats. Protecting cliff nesting sites and minimizing disturbances supports these iconic migratory birds.