Both purple martins and swallows are species of small songbirds, but there are some key differences between them. In this article, we will explore their physical characteristics, behavior, habitat, diet, and more to understand what sets these two birds apart.
Quick Answer
Purple martins and swallows belong to the same avian family, Hirundinidae, but are different species. The main differences are:
- Purple martins are larger, only found in North America, and nest in colonies in human-provided nest boxes.
- Swallows are found worldwide, are smaller, and build mud nests on cliffs, in caves, under eaves, or in burrows.
- Purple martins eat flying insects in flight. Swallows eat flying insects but also glean insects from surfaces.
- Purple martins are completely dependent on human-provided nest sites east of the Rocky Mountains. Swallows are not reliant on human structures.
Physical Characteristics
Though they share some common features, purple martins and swallows have distinct physical differences that allow them to be easily distinguished.
Size
The most noticeable difference between purple martins and swallows is their size. Purple martins are significantly larger. They measure 7 to 8 inches in length with a wingspan around 15 to 16 inches. Swallows are petite in comparison, measuring just 4 to 7 inches in length with a wingspan of 10 to 12 inches.
Coloration
Adult male purple martins are a dark, iridescent purple-black all over. Females are also dark but have light gray undersides. Swallows are generally darker on top but light below. There are several swallow species worldwide that display various colorations. In North America, the most common swallows are the tree swallow, violet-green swallow, barn swallow, and cliff swallow. Tree and violet-green swallows have metallic blue-green plumage on top and white undersides. Barn swallows have rusty orange undersides, and cliff swallows have rufous foreheads and throats.
Wings
Both purple martins and swallows are swift, agile fliers with long, pointed wings. However, a purple martin’s wings appear proportionately shorter and blunter compared to a swallow due to the martin’s larger body size.
Tail Streamers
Purple martins have short, slightly forked tails. Swallow tails come in several different shapes depending on species, but a key difference is that male barn, cliff, and cave swallows have elongated outer tail feathers that trail behind them in flight. Purple martins lack these tail streamers.
Bill
Purple martins have thicker bills than swallows. A martin’s bill measures up to an inch long, while a swallow’s bill is petite, about half an inch long. Both birds have wide mouths suited for catching insects.
Behavioral Differences
Purple martins and swallows share some behaviors in common but have noteworthy differences in their sociality, migration, feeding, and nesting habits.
Sociality
Purple martins are highly social, colonial nesters. They gather in large flocks and nest in colonies of several breeding pairs that can number in the hundreds. Swallows may nest in loose colonies but are not as intensely communal. Colony sizes are smaller, often with just a few dozen pairs nesting in proximity to each other.
Migration
Both purple martins and swallows are migratory in North America. Purple martins spend their winters in South America and return to North America to breed. Different swallow species have varied migration routes and wintering grounds in Central and South America. Martins and swallows both arrive in North America in early spring and leave for their southern wintering grounds in mid to late summer.
Feeding
Purple martins are aerial insectivores, feeding exclusively on insects caught during continuous flight. Swallows are also highly aerial but will occasionally glean insects from branches or the ground. Purple martins feed higher in the air, often 300 feet up or more. Swallows forage closer to the ground and water surfaces.
Nest Sites
One major behavioral difference between the two birds is their nest site selection. Purple martins nest exclusively in cavities, relying on natural hollows or abandoned woodpecker holes west of the Rocky Mountains. East of the Rockies and across much of their range, martins have become completely dependent on man-made nest boxes. Swallows nest in a wider variety of sites. The most common North American species build mud nests on cliffs (cliff swallow), under the eaves of buildings (barn swallow), inside tree cavities or nest boxes (tree swallow), or in burrows dug into sand banks and ditches (bank swallow).
Habitat Preferences
Purple martins and swallows frequent open areas but have different preferred habitats.
Purple Martin Habitat
Purple martins prefer open, rural settings near water and open fields. They nest in older suburbs, parks, and agricultural areas with a mix of fields, forests, and wetlands. Access to suitable nesting cavities is essential.
Swallow Habitat
The habitat preferences of swallows are more diverse depending on species. Cliff swallows live on rocky cliffs, barn swallows in barns and under bridges, tree swallows in open woodlands near water, and bank swallows near rivers, lakes, and grasslands with vertical banks to nest in. All swallows need open flying room, surface water, and habitats supporting dense flying insect populations.
Shared Habitat
Purple martins and swallows frequently share the same open, insect-rich feeding grounds over fields, marshes, ponds, rivers, and lakes. Their nest cavities may even be in close proximity to each other on rural properties and in recreational areas supporting both species.
Diet Comparison
Purple martins and swallows are both aerial insectivores and show some dietary overlap but also key differences.
Purple Martin Diet
Purple martins eat flying insects exclusively, feeding higher in the air than any other North American songbird. Studies show over 85% of a martin’s diet is made up of just three types of insects:
- Dragonflies
- Damselflies
- Bees and wasps
They also consume flies, flying ants, flying beetles, butterflies, moths, airborne spiders, and ballooning spiderlings.
Swallow Diet
Swallows are also aerial insectivores but exhibit greater variation in prey selection depending on the species. The most common insects in their diets include:
- Flies
- Bees
- Wasps
- Flying ants
- Beetles
- Leafhoppers
- Dragonflies
- Mosquitoes
- Butterflies and moths
Swallows will occasionally glean non-flying insects like grasshoppers from vegetation. Over water, swallows hawk insects emerging from the surface, including mayflies, caddisflies, and stoneflies.
Shared Prey
Purple martins share several prey types with swallows, including flies, bees, wasps, ants, beetles, moths, butterflies, and aerial spiders. But martins consume a higher proportion of large insects like dragonflies due to their own larger size and adeptness at catching fast, maneuverable prey.
Differences in Nesting
When it comes to nest site selection, nest construction, and coloniality, purple martins and swallows exhibit major differences.
Nest Sites
As covered earlier, purple martins now rely heavily on artificial nest boxes provided by humans east of the Rockies. West of the Rockies, they still use more natural tree cavities. Swallows are much less dependent on man-made structures and nest in a broader range of sites based on species, including mud nests on cliffs and vertical banks, on cave walls, under bridges, inside tree cavities, or attached to the outside of human structures.
Nest Construction
Purple martins do not build an elaborate nest, relying instead on the cavity itself. Swallows construct intricate cup nests molded from mud and plant fibers, with a rounded tubular entrance on one side. The differences in nest style reflect the different nesting sites selected by each bird.
Bird | Nest Location | Nest Construction |
---|---|---|
Purple Martin | Inside dark cavities | Minimal: twigs, mud, grass |
Swallow | Exposed sites on cliffs, buildings, under eaves | Elaborate mud nests lined with grasses and feathers |
Colonial Nesting
Purple martins are intensely colonial, with several breeding pairs nesting tightly together in the same multi-compartment nest box or site. Most swallow species are loosely colonial, nesting in closer proximity to each other compared to other songbirds but not as densely clustered together as martins.
Geographic Range
Both purple martins and swallows are found throughout North America but purple martins have a more restricted range.
Purple Martin Range
Purple martins only occur in North America. Their breeding range extends north-south across Canada and throughout the continental United States except for the far southwest and northwest. Range maps show them absent from southern California, Nevada, Utah, Arizona, and New Mexico.
Swallow Range
In comparison, swallow species have an incredibly extensive worldwide distribution across North America, South America, Europe, Asia, Africa and Australia. Within North America, swallows can be found anywhere suitable habitat exists from Alaska to Florida and throughout Mexico.
Overlap
Purple martins and swallows broadly overlap across eastern, central and northwestern portions of North America during their shared breeding season. Purple martin range maps show an absence in parts of the western U.S. where swallow species are still present.
Taxonomy
Purple martins and swallows are closely related but do belong to separate taxonomic groupings.
Purple Martin
The purple martin’s scientific name is Progne subis. It is classified in the taxonomic order Passeriformes (perching birds), family Hirundinidae (swallows and martins), and subfamily Pseudochelidoninae, which only includes the New World martins in North America.
Swallow
Swallows belong to the same order Passeriformes and family Hirundinidae but are placed in the subfamily Hirundininae, which encompasses true swallows worldwide. There are around 90 species in this subfamily found on every continent except Antarctica.
Shared Family
Purple martins and swallows share their membership in the broad family Hirundinidae. This taxonomic placement reflects their close ancestry and behavioral similarities as aerial insectivores that nest in colonies and migrate long distances.
Threats and Conservation
As species that depend on aerial insects for food, purple martins and swallows face threats from declining insect populations and loss of foraging habitat from increasing urbanization and pesticide use. They also require suitable nesting sites, which are declining for some species.
Purple Martin Decline
Purple martins have suffered long-term population declines and range retractions. West of the Rockies, they have lost many natural nesting cavities to timber harvests and competition from introduced European starlings. Breeding martins are now rare and local in western states. East of the Rockies, martins shifted dependence to man-made nest boxes but require active conservation and monitoring programs to maintain sufficient cavity housing.
Swallow Declines
Several swallow species including bank, barn, and cliff swallows have declined regionally or across broader ranges, though not as precipitously as purple martins. Losses are attributed to habitat loss, pesticide impacts on their aerial insect prey, and introduced species competing for limited nest sites.
Conservation Needs
To conserve purple martins and swallows, strategies include:
- Monitoring and actively managing cavity nest boxes where needed for martins
- Protecting remaining colonies at natural sites like cliffs and riverbanks
- Reducing pesticide use where possible on breeding grounds
- Promoting organic agriculture and pastureland with ample insect prey
- Preserving large intact wetlands, forests and grasslands for foraging
Conclusion
In summary, purple martins and swallows have key differences in their size, coloring, geographic distribution, nesting ecology, and conservation status. However, they also share critical similarities as aerial insectivores dependent on catching flying insects, migration between North and South America, preference for open habitats near water, and reliance on high-energy insects to raise their young. Maintaining populations of both groups of birds requires protecting their shared feeding and breeding grounds.