The bird that is most well known for having a split or forked tail feather is the barn swallow. Barn swallows are small songbirds with glossy blue-black plumage on their back and wings, and a reddish-orange throat and forehead. Their most distinctive feature is their long, deeply forked tail feathers.
Why do barn swallows have a forked tail?
Barn swallows have evolved a forked tail to aid in their aerial maneuverability and speed. The long, stiff tail feathers allow barn swallows to make quick turns and dives when hunting insects in flight. The forked shape creates more drag and air resistance which allows for greater control and stability in the air. It also acts as a rudder to help steer the bird. The more deeply forked the tail, the more adept the barn swallow is as a flier.
Tail shape and flight ability
Research has shown that barn swallows with the most deeply forked tails tend to be healthier, have greater mating success, and can outcompete others for food resources. This is because tail shape is an indicator of flight performance. Individuals with the optimal tail fork length for their body size are able to fly faster and make quicker turns, allowing them to catch more insects and evade predators.
Sexual selection
The forked tail shape has also evolved through sexual selection. Females preferentially choose to mate with males that have the longest tail streamers and deepest tail forks, as this signals the male’s superior flight skills and overall genetic fitness. Males with longer, more forked tails have greater reproductive success. This has led to the evolution of incredibly long tail feathers in male barn swallows, sometimes up to 25% of their total body length!
How do the tail feathers grow?
The forked tail shape of barn swallows develops as the bird molts and grows new feathers. Juvenile barn swallows hatch with short, unforked tails. As they molt and replace tail feathers, the length and separation between the feathers increases. The tail fork depth reaches its maximum in adult breeding plumage. The outermost tail feathers (the tail “streamers”) are the longest, while the inner tail feathers are shorter, creating the forked shape.
Molting sequence
Barn swallows molt their tail feathers sequentially over time, beginning with the innermost feathers. This molting pattern maintains flight ability, as the outer feathers important for aerial maneuvering are replaced last. In some cases, just the streamer feathers are replaced annually, while the central tail feathers are replaced less frequently.
Delayed maturation in males
Male barn swallows take longer to grow their full adult forked tail shape. Males don’t achieve the long, deeply forked tail typical of breeding adults until their second summer or later. This delayed maturation ensures only the most mature, experienced males with the best flight performance advertise their quality through long tail streamers.
How many tail feathers do they have?
Barn swallows have 12 tail feathers, which is the typical number for most bird species. The 12 feathers are arranged in a fan shape at the end of the bird’s body. They include:
- 2 outermost streamer feathers
- 4 intermediate outer tail feathers
- 2 central tail feathers
- 4 intermediate inner tail feathers
The streamer feathers are the longest, measuring 5-7 inches in adult males. The intermediate and central tail feathers gradually decrease in length towards the center. The fork created between the outer and inner tail feathers may be up to an inch deep in males with the longest streamers.
Fork depth variation
There is considerable variation in tail fork depth depending on factors like age, sex, and geographic location. Some key patterns include:
- Adult males have deeper tail forks than females or juveniles
- Older adult males have deeper forks than younger males
- Barn swallows at higher latitudes tend to have deeper tail forks
The deepest tail forks ever recorded were around 1.7 inches in depth.
How are the tail feathers used in flight?
Barn swallows put their forked tails to expert use while in flight. The specialized tail shape allows barn swallows to perform aerial maneuvers unmatched by other small passerines. The key functions of the tail include:
Steering and control
The barn swallow can fan its tail and adjust the feathers to steer left or right, up or down with high precision. This allows quick dodging and diving.
Stability
The long tail feathers act as a stabilizer and counterweight to the wings, preventing rolling or yawing during flight. This allows smooth gliding and high speed direction changes.
Braking
Fanning the tail creates drag, allowing rapid braking and stopping ability in mid-air. This aids prey capture.
Takeoff
The tail provides essential lift and propulsion during takeoff from a standstill.
How fast can barn swallows fly?
Thanks to their specialized forked tail and pointed wings, barn swallows are capable of very fast flight:
- Cruising speeds of 17-22 mph
- Maximum speeds of up to 35 mph
Some key facts about barn swallow flight speed:
Speed in hunting
Barn swallows reach top speeds when swooping and diving to catch insects in mid-air. This allows them to nab fast-moving prey like flies.
Migration flight
Barn swallows can make long migrations at brisk speeds. They travel 6000-7000 miles between breeding and wintering grounds at sustained speeds over 20 mph.
Rapid dives
These aerial masters can dive at speeds over 35 mph to evade predators or chase prey. Their forked tails allow fast re-orientation at the bottom before pulling up.
Comparison to other birds
Barn swallows are faster than similar-sized songbirds like warblers but slower than swifts. Peregrine falcons can reach speeds over 200 mph in diving stoops.
Where do barn swallows live?
Barn swallows inhabit open, rural environments across much of North America, Europe, Asia, and Africa. Some key elements of barn swallow habitat include:
Nesting habitat
Habitat | Description |
---|---|
Farms | Barns, stables, sheds, and other rural structures provide nest sites |
Bridges | Undersides of bridges are used for nest placement |
Cliffs | Natural rock crevices and caves provide nesting sites |
Access to mud for nest construction and open habitat for insect hunting are key.
Migration
Barn swallows migrate long distances between nesting and wintering grounds. They winter in Central and South America and the Caribbean.
Decline in natural sites
The loss of natural cliff nesting habitat has led barn swallows to increasingly rely on man-made structures.
Adaptable birds
Barn swallows readily adapt to using human structures, allowing them to thrive across many habitat types.
What do barn swallows eat?
Barn swallows are aerial insectivores, which means they eat insects caught while flying. Some key facts about their diet include:
Primary foods
- Flies
- Moths
- Bees
- Wasps
- Dragonflies
Swallows perform aerial acrobatics to catch insects on the wing.
Foraging behavior
Barn swallows hunt individually or in flocks, typically fairly close to the ground. They grab prey in their beak and eat while gliding.
Amount of food
Swallows eat about 850 insects per day. Excellent flying skills allow them to eat enough to sustain their high metabolism.
Water
Swallows get most of the water they need from their insect prey. They also drink by skimming over and catching water in flight.
How do barn swallows nest?
One of the most distinguishing features of barn swallows is their cup-shaped mud nests. Some key facts about their nesting habits include:
Nest locations
As their name implies, barn swallows often nest inside barns and other structures. But they will nest on any suitable vertical surface, including cliffs, cave walls, and highway bridges.
Nest construction
Material | Purpose |
---|---|
Mud pellets | Used to build up cup shape as base |
Grasses | Lined inside of nest for insulation |
Feathers | Add softness for eggs and chicks |
Both male and female work to construct the nest, though the mud gathering is done primarily by the female.
Clutch size
A typical barn swallow clutch contains 4-5 eggs. The female incubates the eggs for about 14 days before they hatch.
Parental care
Both parents help feed and care for the chicks until they fledge at around 19 days old. Barn swallows frequently raise 2 broods per year.
Return to nests
Barn swallows exhibit nest site fidelity, returning to previous nest locations year after year. Old nests are refurbished or new ones built on top.
Are barn swallows territorial?
Barn swallows exhibit variable territorial behavior depending on the stage of breeding:
Nest site defense
Barn swallows fiercely defend the area around their nest from intruders. Dive-bombing is used to drive away competing swallows or other birds.
Foraging territory
During nesting, barn swallows establish feeding territories up to 300 feet around the nest. They chase away other swallows entering the space.
Migration and wintering
In migration and winter, barn swallows form large communal flocks and do not maintain individual territories.
Colony nesting
When suitable sites are limited, barn swallows nest colonially with minimized territorial behavior.
So in summary, barn swallows are territorial mainly for nesting purposes. At other times they are highly social and colonial.
How do barn swallows communicate?
Barn swallows have complex social behavior and use vocalizations and physical displays to communicate. Some of the key ways barn swallows communicate include:
Song
Male barn swallows have a distinctive raspy, gurgling song used to attract females and defend territories.
Calls
Various metallic chip and rattle calls communicate different information between individuals in a flock.
Visual displays
Dramatic swooping flight displays communicate aggression or courtship. The forked tail is visually conspicuous.
Nest display
Females assess males in part by the intricacy, symmetry, and size of their nests.
Mobbing
Group mobbing of predators or intruders helps relay danger information rapidly.
What are the predators of barn swallows?
Despite their excellent flying abilities, barn swallows face threats from certain predators. The main natural predators of barn swallows include:
Falcons
Falcons like the American kestrel are able to grab and kill barn swallows with their powerful talons during flight.
Hawks
Sharp-shinned hawks and Cooper’s hawks specialize in ambushing and killing small songbirds.
Jays
Jays like the blue jay sometimes raid swallow nests, eating eggs and chicks.
Snakes
Snakes can climb into barn swallow nests and consume eggs or young.
House cats
Domestic and feral cats frequently catch barn swallows, especially fledglings and juveniles.
Are barn swallows endangered?
Barn swallows remain widespread and have adapted well to nesting on human structures. However, there are some conservation concerns:
- Population declined by around 25% from 1966 to 2015
- Declines attributed to conversion of rural habitat and barn removal
- Listed as threatened or endangered in some U.S. states
- Legally protected from nest removal or harm in many areas
While not globally threatened, maintenance of populations depends on conservation of suitable rural habitat and nesting barns.
Barn swallow symbolism
Beyond their physical elegance and aerial agility, barn swallows have inspired symbolic meaning across cultures:
Fertility and new beginnings
Associated with spring arrival and renewal in Northern climates.
Change and freedom
Their migratory habits symbolize a carefree spirit.
Communication
Believed to ferry messages between worlds by some traditions.
Community
Their social, colony-nesting behavior represents family and togetherness.
Luck and good fortune
Spotting swallows or their nests is seen as auspicious by many peoples.
Conclusion
With their distinct forked tail shape, barn swallows stand out for both their graceful flight and bubbly social nature. These aerial hunters put their specialized tails to work chasing insects from farm to farm. The synergy of flight performance and attractive tail plumes has shaped barn swallow natural and cultural history for millennia. Despite challenges from a changing world, barn swallows look to continue gracing fields and barns with their speed, skill, and charm for the foreseeable future.