The Barn swallow (Hirundo rustica) is one of the most widely distributed birds globally. In fact, this hugely successful bird is likely the most widely distributed Passerine bird and lives on every continent except Antarctica.
Barn swallows are fairly vocal birds, and can usually be heard frequently calling during their impressive displays of acrobatic flight. Chances are, wherever you live, a Barn swallow likely lives near you.
In this article, we'll dive into the details of Barn swallow nesting behaviors along with the type of habitat, and many more interesting facts.
As the name suggests, Barn swallows typically nest in buildings. They’ve had a close relationship with humans for thousands of years and are one of the most studied birds. While many building-nesting birds are deemed a nuisance, Barn swallows are often encouraged as they keep insect populations at bay. Barn swallows prefer open buildings near fields or agricultural land. Rarely, they choose to nest in rocky alcoves or cliffsides.
Barn swallow nests are quite incredible as they can be built on platforms or on vertical walls or beams. To secure the nest to the wall, Barn swallows trowel mud and mix it with grass, stems, and other foliage. Then, they plaster the mud to the wall before lining the nest with soft leaves and feathers. The result is a mud-cup nest ‘glued’ to a vertical wall or beam.
Because they use mud to build the nest, Barn swallows typically choose nesting sites near water. They’re often spotted scooping up mud in their small beaks, transporting it to the nest, and applying it carefully. They can make some 15 trips to and from the nest per hour. Both the male and female build the nest, though the female often does the bulk of the structural work.
Of course, there’s much more to learn about the nesting habits of these fantastic birds!
|Key Barn Swallow Nesting Facts|
|Nesting season||May to August|
|Nesting material||Trowel mud, mixed with grass, stems, and other foliage|
|Nest type||Mud, platform or vertical on walls and beams|
|Nest location||Open buildings near fields or agricultural land|
|Number of broods||Two broods|
|Clutch size||4 - 5 eggs|
|Egg colour||Creamy white or soft pink-white, with dark spotting|
|Egg size||20 x 14 mm|
|Egg weight||1.9 g|
|Incubation period||16 - 18 days, mainly by the female|
|Fledgling period||20 - 22 days|
|Use nest boxes||Yes|
Barn Swallow feeding chicks inside the nest
Barn Swallow gathering mud for nest construction
Barn swallow nests are small, cup-shaped, and made from mud. They are usually built on a ledge or in a crevice. These distinctive nests are crafted from small pellets of mud that are glued together to create a hard three-dimensional form. Once the mud cup has been secured, the birds work together to line the interior with grass and feathers.
Barn swallow nests are either built on a vertical or horizontal plane. Some studies have shown that the birds prefer to build nests on a horizontal platform (as is conventional), but they’re perfectly content to build on a vertical wall or beam with no support from below.
Barn Swallow feeding chicks inside the nest
Barn swallow nesting in North America and Central Europe typically starts in late April and early May, but in North Europe, they might wait until June or even later. In the south, Barn swallows can nest as early as November. In Argentina, for example, nest building often gets underway in late October, depending on the weather.
In hotter climates, Barn swallow nesting occurs throughout much of the year. The birds may raise as many as three broods, either in sequence or dispersed throughout the year.
Barn swallow in the nest
Barn swallows typically lay eggs in May at the earliest in North America and Central Europe. In northern Europe, e.g., Russia and Scandinavia, egg-laying occurs later, around June.
In the south, e.g., in Central and South America, egg-laying occurs earlier. In Argentina as early as November.
Barn Swallow chicks in the nest waiting to be fed
Barn swallows take around 14 to 20 days to build their nest, the young are incubated for 14 to 16 days, and the young will leave the nest in 18 to 23 days.
Then, the pair may raise a second brood shortly after. If Barn swallows raise a second brood, they reuse the same nest about 50% of the time. Nests are often reused year after year. Overall, Barn swallows probably nest for around two months.
Barn swallows return from migration and inspect many nesting sites in quick succession. These gregarious birds often build their nests in close proximity to each other (around 30cm minimum).
A typical nesting site is well-sheltered and covered from the rain, which is vital to ensure the nest isn’t ruined by bad weather. In addition, while Barn swallows often prefer to build on a hard, horizontal platform, they often build their nest on a vertical wall or beam.
Once the nesting site is chosen, the male and female will work together to gather mud from a nearby pond, lake, or puddle. Then, they scoop the mud up in their mandible and apply it to the wall incrementally. The mud cup is around 10 to 15cm wide, and the walls are approximately 2.5cm thick.
A nesting pair of barn swallows collecting mud to build the nest
The main mud cup structure can take around two weeks to build. Once complete, the birds will start to line the cup with grass and feathers, which can take approximately five days. The resulting structure is often very strong, and some have reportedly survived for 30-years!
The breeding success of Barn swallows is also typically high (70 to 90%), which is a testament to the dedication and ingenuity of these magnificent birds.
Barn Swallow building the nest
Baby barn swallows typically leave the nest and fledge after around 18 to 23 days, but they can leave after just 14 days if the nest is disturbed.
After they leave the nest, the parents often feed the birds for another 1 to 2 weeks before becoming fully independent.
Barn swallows have between 1 and 3 broods per year. In Europe and North America, they’re more likely to have a single brood, or two broods at most. If the couple raise a successful brood early in the season, they’re more likely to have a second.
In warmer climates, Barn swallows may have three broods dispersed over a period of 2 to 5 months.
A Barn swallow feeding recently fledged chicks
Barn swallows often reuse the nests for their second broods and the next breeding season. One study showed that some 44% of Barn swallows of the same colony reused the same nests the following year after they were built.
When Barn swallows return to their nesting sites, they inspect the nests for their quality and also check for any parasites or nesting insects. Clean, sanitary nests are prioritized. Some long-lasting nests last for years - one in Nebraska survived for around 30-years and was maintained with new mud every year.
Barn sparrow eggs are a creamy white or soft pink-white. They’re slightly glossy and are adorned with purplish, reddish, brownish, or light-brown spots.
Barn Swallow eggs inside the nest
Barn swallow eggs measure around 2 x 1.4 centimeters. The eggs are ovular rather than elliptical and are extremely small, weighing just 1.8 to 2.0g.
Barn swallows are considered cavity-nesting birds and will use sheltered nest boxes mounted underneath covered areas.
These types of nesting boxes are best installed in open, wooden structures (e.g., barns), next to farmland or open fields. Barn swallows are excellent for keeping insect populations at bay.
Hungry Barn swallow chicks begging for food
Barn swallows will certainly nest in any outbuildings, especially wooden barns and covered, open buildings. However, they’re also observed attaching their nests to steel structures.
If you have a tall, open structure in your backyard, then Barn swallows might be attracted to it. They prefer nesting sites that are well-sheltered from the wind and rain.
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