Fact Sheet FS1378
Male barn swallow, displaying steely blue back and flight feathers with a rufous throat and breast.
The barn swallow (Hirundo rustica) is a globally widespread songbird that can be found in a variety of open habitats across the Americas, Africa, Europe, and Asia. Barn swallows have close associations with people because they readily nest on man-made structures and forage within farms, parks, and other open areas. Beyond their cultural familiarity, barn swallows are ecologically valuable because they consume large numbers of flying insects, many of which are pests to people, crops, and livestock. Unfortunately, changes in farming practices, pesticide use, and the loss of traditional nesting structures have contributed to declines in barn swallow populations in some regions. This fact sheet will describe barn swallow ecology and behavior, and it will highlight ways that landowners and communities can support barn swallow colonies.
Description
Barn swallows exhibit steely blue wings, back and tail, and a rust-colored or rufous throat and forehead. Their underparts are a tawny or buffy orange. Notably, barn swallows have a deeply forked tail (whereby the outer tail feathers extend beyond the wingtips) with a white band. While both sexes share the same coloration, males have bolder coloring and longer outer tail feathers compared to females. On average, adult barn swallows are between 5.9 and 7.5 inches long, with an approximate 11.4 to 12.6 -inch wingspan, and they usually weigh between 0.6–0.7 ounces.
Barn swallow nest of mud and grasses attached to the wooden ceiling joist of a barn, with four nestlings eagerly awaiting food from their mother.
Distribution and Habitat
Barn swallows are found on every continent except Antarctica. In North America, they breed throughout Canada, the United States, and northern Mexico, and they overwinter in Central and South America. Their three primary habitat requirements include: 1) open areas to feed on insects, 2) cliffs or structures to build nests, and 3) sources of wet mud for nest construction. Given these requirements, barn swallows commonly occur in open fields, parks, wetlands, meadows, ponds, lakes, rivers, coastal bays, estuaries, beaches, agricultural lands, and rights of way.
Prior to European colonization in North America, barn swallows typically nested within colonies on cliff faces, ledges, and crevices. With the expanding human footprint, they transitioned to exploiting man-made structures for breeding. Today, they nesting colonies are mostly found inside barns, sheds, bridges, and other types of buildings. Nests are usually found on rafters, cross beams, or ledges. Barn swallows also construct nests on the exterior of buildings, provided there is an overhang creating shelter from weather and aerial predators. Nests can also be built on the side of a vertical wall if the surface is rough enough for mud and grasses to adhere to. Smooth surfaces, such as vinyl or aluminum, are avoided. Barn swallows build their nests from hundreds of small mud pellets, a behavior that is relatively rare among songbirds.
A barn swallow flying low over a marsh, hunting for insects.
Foraging Behavior
Barn swallows are highly agile aerial insectivores that capture prey mid-flight with swift, acrobatic maneuvers. Their long, pointed wings and deeply forked tails allow them to turn sharply and change direction with remarkable precision, making them especially effective at chasing insects on the wing. They are often seen gliding low over fields, water, or roads, with foraging activity peaking in the morning and evening when insect numbers are highest. During cool or rainy weather, when insects fly closer to the ground, barn swallows can be observed swooping just above lawns, fields, and ponds in search of food.
Barn swallows feed almost exclusively on flying insects such as flies (including biting species, e.g., horseflies and mosquitoes), beetles, moths, and true bugs. Many of the insects eaten by barn swallows are pests with direct impacts on people and agriculture: mosquitoes spread disease, tarnished plant bugs damage crops, cherry fruit worms infest fruit trees, and horseflies are a nuisance to livestock and humans. By consuming hundreds of insects per day and thousands collectively as a colony, barn swallows provide valuable natural pest control that benefits farms, homes, and communities.
Barn swallows usually forage within a few hundred meters of their nesting colonies but can travel farther when food is scarce. Because they spend so much time foraging around farmland, barns, and rural structures, encouraging colonies on private property can provide both ecological and practical benefits. Their presence reflects a healthy insect community and contributes directly to reducing nuisance insects around people and livestock, while also lowering insect pressure on crops.
Reproduction/Nesting Behavior
Barn swallows are known for their intricate nesting and reproductive behaviors, and individuals often return to the same nesting sites year after year. Barn swallows are socially monogamous, meaning that previous breeding pairs often reaffirm their bond once back on the breeding grounds. However, females do engage in extra-pair copulations with other males during the breeding season, which lasts from March through September. At the breeding location, males perform a courtship display to attract females, which includes fluttering around the nesting site, showing off their mud-carrying abilities, and singing to signal their suitability as a mate. Nests are constructed by both the male and female over the course of two weeks, with over 1,000 trips typically needed to collect mud and other materials. Adults mix the mud and grasses inside of their bills before affixing them to nest substrate (rafter, ledge, etc.). When nesting on a vertical structure, they will first create a ledge and then build the nest upward to form a semi-circular cup against the wall of the structure. If they choose to build a nest on a flat shelf, they will form a completed nesting cup, approximately 3 inches across and 2 inches deep. Once the nest is complete, adults will line the nest cup with feathers and grass in preparation for egg-laying. Barn swallows will nest in loose colonies if conditions are appropriate, with nests anywhere from 3 to 25 feet apart from each other. Males will defend the small territory immediately around their nest and will act aggressively towards any encroaching birds.
Females usually lay 3 to 7 eggs, incubating them for approximately 2 weeks while the male assists by bringing food. Hatchlings are born with their eyes closed and completely naked, except for some tufts of down feathers. Both parents are highly involved in feeding the chicks, with the male often taking on the role of guarding the nest and helping to protect the young from predators. Chicks grow quickly, fledging in 3-4 weeks. In favorable conditions, barn swallows often raise two broods per season, and occasionally even a third, making them one of the more productive songbirds in agricultural landscapes.
Barn swallows a) hatch after about 2 weeks of incubation; remain as b) flightless nestlings for up to 3 weeks; and then c) fledge but often remain at the nest for a few weeks. Photo credits: (l, m) Kati Fleming, (r) Brenda Asterino.
Status and Conservation
Barn swallows are widespread and not considered at significant risk globally, but their populations have declined in parts of Europe and North America. In North America, long-term monitoring indicates population declines of roughly 50–70% over the past 40 years. These declines are linked to habitat loss, particularly the reduction of traditional nesting sites as old wooden barns and other open structures are renovated or replaced by modern buildings, which are less suitable for nesting. Declines in insect availability due to intensive pesticide use have also played a role. Despite these regional challenges, barn swallows remain common overall and are currently listed as "Least Concern" on the IUCN Red List, reflecting their large global population and wide distribution. Protecting older structures or providing artificial nesting sites can help support local populations and ensure that barn swallows remain a familiar presence in rural landscapes.
Typical open–access wooden barn versus a more modern metal building with no access for barn swallows.
Habitat Enhancement
To mitigate the loss of nesting habitat, there are several options to create artificial structures to promote barn swallow breeding.
Artificial Nesting Cups
Barn swallows will readily utilize artificial nesting cups, which mimic natural mud nests but are made from wood or a plaster-like material. Installing artificial nesting cups can significantly offset the loss of nesting habitat and has been shown to increase reproductive success by 75% in mated pairs. Further, breeding pairs are more likely to return to a previously successful nesting site. Artificial nest cups can be purchased online from commercial sellers or made at home.
Left: Artificial barn swallow nests can be constructed of wood and affixed to manmade structures to promote breeding.
Right: Artificial nesting cups installed between ceiling joists to ensure limited view between neighboring nesting birds. Photo credits: Richard and Diane van Vleck.
Artificial Nest Requirements:
Nesting Platforms
Alternatively, you can increase nesting habitat inside of a barn or other open-air structure by installing simple wooden nesting platforms that provide a horizontal ledge for barn swallows to build a nest on. Platforms should be approximately 3–5 inches wide and 6–8 inches long.
Nesting platforms inside a New Jersey barn support a large colony of barn swallows. Photo credit: Erin McHale.
Nesting Structures
With the continued demolition of old wooden barns and buildings, available structures to mount artificial nests or nesting platforms may be limited. However, dedicated barn swallow nesting kiosks offer an alternative way to continue supporting barn swallows. Nesting kiosks are tall, roof-covered structures, typically rectangular in shape, that contain nesting platforms or artificial nesting cups for barn swallows to use. Ideal kiosks are constructed with rough-surfaced wood to make it easier for barn swallows to attach nests if they choose to build their own. Nesting kiosks should also contain deterrents to reduce the risk of predation from ground predators, such as feral cats and raccoons. Baffles or metal cylinders around the support posts of the structure are effective. Nesting kiosks work best if they are a short distance from suitable barn swallow foraging habitat, such as pastures, fields, waterbodies, or forest edges.
Example of a large barn swallow nesting kiosk (upper left) with artificial nesting cups installed between each ceiling joist (right and bottom). Photo credit: Richard and Diane van Vleck.
Avoid disturbing nests during the breeding season. Perform maintenance of structures containing nests outside of the breeding season (repairs, cleaning, painting). Barn swallows should be excluded from nesting prior to the breeding season if it is known that their nesting structure will undergo alteration during the breeding season.
More Tips for Enhancing Barn Swallow Habitat
References
December 2025
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