Swallows are small, agile birds found throughout the world. There are over 80 different species of swallows that can be divided into several main groups based on physical characteristics and geographic location.
Swallow Species Groups
The major groups of swallows are:
- Barn swallows
- Cliff swallows
- Tree swallows
- Bank swallows
- Cave swallows
- Saw-wing swallows
Let’s take a closer look at each of these groups of swallows:
Barn Swallows
There are around 16 species of barn swallows. Some of the most widespread barn swallow species include:
- European barn swallow
- American barn swallow
- Red-chested swallow
- Angola swallow
- Pacific swallow
- Welcome swallow
Barn swallows are very recognizable with their long, deeply forked tails. They are usually colored blue above and pale orange or reddish-orange below. Barn swallows build cup-shaped mud nests on vertical surfaces such as cliffs, walls, and barn rafters.
Cliff Swallows
There are around 6 species of cliff swallows including:
- African cliff swallow
- American cliff swallow
- Congo cliff swallow
As their name suggests, cliff swallows nest in colonies on cliff sides. They build gourd or flask-shaped mud nests with small entrances near the top. Cliff swallows have chunky bodies, short tails, and square tails. Their plumage is mostly blue-black above and pale below.
Tree Swallows
The 10-15 species of tree swallows are found throughout North America. Some examples are:
- Bank swallow
- Violet-green swallow
- Bahama swallow
- Golden swallow
- Mangrove swallow
- White-winged swallow
Tree swallows are slender with pointed wings and short, forked tails. Their backs are iridescent blue-green and they have clean white undersides. Tree swallows nest in tree cavities often created by woodpeckers.
Bank Swallows
The bank swallow group contains around 4 species including:
- Bank swallow
- Ethiopian cliff swallow
Bank swallows are small with brown and gray plumage. They nest in colonies in burrows dug into vertical dirt and sand banks near water. Bank swallows have a brown band across their chest.
Cave Swallows
The 3 species of cave swallows are:
- Cave swallow
- Chestnut-collared swallow
Cave swallows are similar to barn swallows but with square tails rather than forked. They build nests on cliffs or cave walls. These swallows are found in the Americas.
Saw-Wing Swallows
The single species of saw-wing swallow is found in Australia. Saw-wing swallows have unique serrated wing edges that produce a buzzing sound in flight. Their plumage is mostly blue-black with a rusty colored throat.
Swallow Characteristics
Despite the many different swallow species, they share some common physical traits and behaviors including:
- Small, streamlined bodies built for fast, aerobatic flight
- Pointed wings and short bills suited for catching insects in midair
- Iridescent blue, green, or brown plumage on their backs
- Pale underparts ranging from white to reddish-orange
- Nesting behavior that involves mud or burrows
- A diet consisting entirely of insects caught on the wing
- Gregarious nature – often feeding and migrating in large flocks
- Worldwide distribution across all continents except Antarctica
Swallow Taxonomy
Swallows belong to the family Hirundinidae which is in the order Passeriformes. Key features of Passeriformes include:
- Small to medium sized
- Legs suited for perching instead of walking
- Bills used for catching insects, seeds or fruit
- Vocal abilities for bird calls and songs
Other well-known Passeriformes birds include finches, warblers, sparrows, and crows. There are over 5,700 species in this diverse order.
Within the Hirundinidae family, DNA studies show swallows are most closely related to martins. Martins look nearly identical to swallows but with larger, sturdier bills. Other relatives in the Hirundinidae family include the saw-wings and crag martins.
Swallow Habitats
Most swallow species live in open, rural habitats that provide the airspace needed for feeding on aerial insects. Some key swallow habitats include:
- Farmlands
- Grasslands
- Meadows
- Marshes
- Lakes/rivers
- Woodland edges
Cliffs, caves, trees, and structures like barns or bridges are needed for nesting sites. Some swallows have adapted to more urban or wooded environments as long as adequate food, water, and nesting sites exist.
Swallow Migration
The majority of swallow species migrate long distances to find favorable nesting conditions and an abundance of flying insects. Migration patterns include:
- Northern hemisphere species breed in North America and Northern Europe. They winter in Central and South America or Africa.
- Southern hemisphere species breed in Australia or Africa and winter in Asia or the Mediterranean region.
- Travel between 6,000-13,000 km between breeding and wintering grounds.
- Migrate in large mixed flocks for safety and navigation.
- Return to the same nesting sites and partners year after year.
A few tropical species like the mangrove swallow are non-migratory. The wide distribution of suitable habitat allows them to nest and feed in the same region year-round.
Threats to Swallows
Many swallow populations face a variety of threats including:
- Habitat loss from development
- Declines in aerial insects due to pesticides
- Climate change affecting migration patterns and timing
- Extreme weather events during migration
- Competition for nesting sites with invasive species
- Collision hazards from structures, vehicles, and transmission lines
Ongoing conservation efforts aim to protect essential breeding and wintering grounds. Providing more nest boxes and reducing pesticide use also helps sustain healthy swallow populations.
Fun Facts About Swallows
- Swallows constantly catch and eat insects during flight. They drink by skimming across water surfaces and swallowing.
- Barn swallows are one of the most widespread birds in the world. They are found on every continent except Antarctica.
- Cliff swallows build nests out of up to 1,000 loads of mud. Nests often last multiple years.
- The barn swallow’s forked tail inspired the creation of the bowtie.
- Tree swallows aggressively defend nest sites against other cavity nesters. They may mob potential intruders in flight.
- Bank swallows dig long burrows with nest chambers at the end. Burrows are often 1-2 meters long.
- The welcome swallow of Australia travels 35,000 km roundtrip during annual migration.
- Some swallow nestlings can fly short distances at only 10-12 days old.
- Swallows moult and regrow all their feathers every year after breeding.
- Swallows roost communally in groups up to several million birds during migration.
Conclusion
Swallows are elegant, agile birds superbly adapted to catching insects on the wing. Their impressive aerial abilities, long migrations, and communal habits make them fascinating to observe and study. With over 80 species found worldwide, swallows occupy diverse habitats ranging from rocky cliffs to open farmlands. Protecting their intricate mud nests and mitigating threats during migration are key steps to conserving populations of these iconic birds into the future.
