The barn swallow is a small bird in the swallow family that is found across the Northern Hemisphere. It is known for its blue upperparts, dark pink underparts, and long forked tail. Barn swallows are highly adaptable birds that live in close proximity to humans and can be found in a variety of habitats during their breeding, migration, and wintering periods.
What are the characteristics of a barn swallow?
Barn swallows are small, slender songbirds that are approximately 15 to 19 cm (6 to 7.5 inches) in length. They have steely blue upperparts and a cinnamon-buff or pale chestnut underparts. Their long wings have a dark blue-black wash and their deeply forked tail is generally the same shade of blue-black. Adult male and female barn swallows look similar, but juveniles have pale fringes on their feathers which create a scaly look on their back and wings.
A key identifying feature of the barn swallow is its long, deeply forked tail. The outer tail feathers are generally the longest and can be up to 9.8 cm (3.9 inches) in length. When perched, the barn swallow often fans its tail and the long outer feathers are clearly visible. The tail shape gives the barn swallow extra maneuverability and aids its fast, agile flight.
The calls of the barn swallow are a mixture of shrill trills and rattling sounds. Their song is a pleasant, twittering warble.
Where do barn swallows nest?
Barn swallows almost always nest close to humans, building their cup-shaped mud nests on vertical surfaces of man-made structures such as barns, stables, sheds, and under bridges. They will use both the interior and exterior areas of buildings for nesting. Favorite nesting spots include ledges under roofs, windowsills, beams, and rafters. The mud nests are lined with grass and feathers and are generally reused in subsequent seasons.
Less commonly, barn swallows may also nest in natural sites such as cliffs, caves, and tree cavities. But they overwhelmingly prefer human-made structures, likely because these offer more ideal nesting habitat of vertical surfaces and eaves that provides protection from predators and inclement weather.
Ideal nesting conditions
When selecting a nest site, barn swallows look for the following ideal conditions:
- A vertical surface such as a wall, beam, cliff face, etc.
- A ledge, cavity, or crevice that provides a base to attach their nest
- An overhang above the nest that provides shelter
- Sufficient space below the nest so that they can drop into flight
- Adequate mud and water sources nearby to build their nest
- Protection from predators
- Dark and undisturbed areas away from human activity
Areas that meet these criteria allow for successful nesting and the raising of young. Barn swallows demonstrate high nest site fidelity and often return to the same nesting site year after year.
Where does the barn swallow migrate and winter?
Barn swallows are one of the most widespread swallow species and have an enormous global range. They breed across North America, Europe, and Asia and undertake annual migrations to subtropical and tropical regions for the winter.
Here are the key migration and wintering areas for barn swallows that breed in different regions:
Breeding Range | Wintering Range |
---|---|
North America | South America, Central America, Caribbean islands |
Europe | Sub-Saharan Africa |
Northern Asia | Indian subcontinent, Southeast Asia, northern Australia |
Barn swallows are capable of undertaking remarkably long migrations between their breeding and wintering grounds. For example, those nesting in North America may travel over 8,000 km (5,000 miles) each way on their annual migrations down to South America and back.
Winter habitat
During the winter, barn swallows seek out open and semi-open habitats below 2000 m (6500 ft) in elevation where flying insects are abundant. Favored wintering habitats include:
- Grasslands
- Farmland
- Marshes and lakes
- Cultivated areas
- Partially open woodland
- Suburban and urban areas
They mainly roost in marshes and reedbeds at night and forage in open areas by day. Even while wintering, barn swallows remain highly associated with humans and are frequently found around rural farms, plantations, pastures, and even urban environments.
What are the breeding habits of the barn swallow?
Barn swallows arrive back on their breeding grounds beginning in late winter. Courtship and pair bonding occurs in March and April, and the female begins building the mud nest in April or May. The cup-shaped nests are lined with grass and feathers and are typically situated on a vertical wall or beam.
Clutch size is between 3-7 eggs with 4-5 being typical. The female incubates the eggs for 14-16 days before they hatch. Both parents feed the nestlings with flying insects captured on the wing. The young fledge the nest in 18-23 days after hatching.
Barn swallows routinely have 2-3 broods per breeding season with the later broods often utilizing the same nest. The female carries out most of the construction of the new nest while the male continues to care for the fledglings. After their population crashed in the 20th century, barn swallows have adapted to successfully raise more broods per season to recover their numbers.
Ideal breeding habitat
Productive breeding habitat for barn swallows consists of open and partly open areas with a source of mud and water for nest construction. Good foraging areas are critical and include:
- Rivers and lakes
- Ponds
- Marshes and wetlands
- Grasslands
- Pastures
- Farmland
Access to suitable nesting sites on man-made structures nearby is also essential. Ideal breeding habitat provides ample flying insects to feed their young and allows barn swallows to successfully raise multiple broods.
What does the barn swallow eat?
Barn swallows are aerial insectivores meaning they catch and eat insects on the wing. Some key prey items include:
- Flies
- Bees
- Wasps
- Butterflies
- Moths
- Grasshoppers
- Crickets
- Beetles
- Ants
Swallows grab insects in their beak and eat them mid-flight or carry them back to perches for their young. Barn swallows drink by skimming the surface of water bodies while flying.
A key factor determining barn swallow habitat quality is the availability of large flying insects. Good foraging areas offer open habitats near water where insect diversity and abundance is high.
Hunting techniques
Barn swallows use the following techniques while hunting on the wing:
- Hawking – This involves flying with the beak open to catch insects.
- Sallying – The swallow perches and makes aerial sallies out to catch passing insects before returning to its perch.
- Aerial picking – Plucking stationary insects like bees and wasps right off surfaces in flight.
Their adept flying skills, sharp eyesight, fast reflexes and maneuverability make barn swallows excellently adapted aerial hunters.
What are some interesting barn swallow facts?
- Barn swallows have one of the longest migrations of any bird, traveling up to 8,000 km (5,000 miles) each way between their breeding and wintering grounds.
- They can fly up to 50 km/hr (30 mph) and make sharp aerial twists and turns when hunting.
- Mud pellets are carried in their beak to construct nests. Sticky saliva helps them adhere the pellets to walls and beams.
- Their long forked tails gives them greater agility in flight compared to other swallow species.
- Pairs often return to repair and reuse the same nest in consecutive years. Some nests are used for over 15 years.
- Barn swallows live an average of 2-3 years but the longest recorded lifespan is over 11 years.
- They are very social, often gathering in huge flocks during migration and on their wintering grounds.
- Population declines due to habitat loss and climate change are concerns for the future of barn swallows.
Symbolism
Due to their association with humans, barn swallows have long been seen as a symbol of the home and the link between mankind and nature. Their mud nests built using human structures represents home and their migrations represent the changing seasons.
Conclusion
In summary, barn swallows are graceful aerial acrobats that nest in close proximity to humans across the Northern Hemisphere. Their long migrations take them between summer breeding grounds across North America, Europe and Asia, and wintering areas in Central and South America, Africa, and Australasia. Swallows prefer open country near water for nesting and foraging and they continue relying on barns and other man-made structures to raise their young. Efforts to reduce habitat loss and promote insect-friendly areas will be important for the future conservation of the beloved barn swallow.