Catching sight of a small silhouette gracefully soaring overhead in the summer sun, it’s not always easy to identify what species it is, particularly when there are many similarities in size and flight style. Two easily confused species are the Barn Swallow (Hirundo rustica) and the Purple Martin (Progne subis): both are agile, aerobatic birds and symbols of summer.
However, on close inspection, there are many distinguishing characteristics between Purple Martins and Barn Swallows, both in appearance and behavior. We’ll be looking at these in depth here, so read on to learn the key differences and become an expert at identification.
Purple Martins and Barn Swallows are closely related members of the swallow family of birds, classified as Hirundinidae, so it’s understandable that sometimes the two species are confused. They are similar in size and shape from a distance, but when compared side by side, differences become more apparent.
Purple Martins are larger in size than Barn Swallows, measuring 19 cm to 20 cm (7.5 in to 7.9 in) in length, weighing 45 g to 60 g (1.6 oz to 2.1 oz) and having a wingspan of 39 cm to 41 cm (15.3 in to 16.1 in). Males are a dark iridescent purple-blue all over, while females are usually lighter on their breast and belly, with silvery-gray underparts. They have stocky bodies, with a broad wingspan and their forked tail is slightly rounded.
In contrast, Barn Swallows are slightly smaller in size, measuring 17 cm to 19 cm (6.5 in to 7.5 in), weighing 16 g to 22 g (0.6 oz to 0.8 oz) and with a wingspan of 32 cm to 34.5 cm (12.5 in to 13.5 in). Barn Swallows are more slender in shape, with longer trailing tail forks that measure up to 7 cm (3 in) and pointed wings.
Another key way to tell these two species apart is their coloring. Barn Swallows display a bright chestnut-red forehead, face and throat, marked with a bold dark band, and a paler buff belly and underwings. Their back, neck and upper wings are a vibrant steely blue.
A Purple Martin perching on a wooden post
A Barn Swallow perching on a branch
Barn Swallows are resident in more diverse habitats, with a preference for rural landscapes, including open meadows, pastures and farms. In Asia and North Africa, they are also widespread in residential settlements.
Purple Martins, however, are more at home in populated areas and are highly dependent on humans for survival. Competition for suitable nest sites is a major issue for urban-dwelling Purple Martins, and they now almost solely rely on artificial nesting pods supplied by humans for breeding.
There is some overlap between the natural range of Barn Swallows and Purple Martins. However, while Purple Martins are limited to North and South America, Barn Swallows are also found further afield and are the world’s most widespread swallow species, found on every continent except Antarctica.
In North America, Purple Martins are concentrated in the eastern regions of Canada and the United States and may be seen across the southern US and Central America on migration passage to South America each fall.
Barn Swallows are the world’s most widespread member of the swallow family and breed across almost the entire US, much of southern and western Canada, and across Europe, Asia and parts of North Africa. Non-breeding territories are found in Central and South America, sub-Saharan Africa, south and south-east Asia and northern Australia.
Purple Martins have a reputation as being calm and non-aggressive, and will generally lose out to more competitive species such as House Sparrows and Starlings for nest sites. Barn Swallows are more resilient and feisty, and fiercely territorial over their nesting sites, frequently dive-bombing any intruders that approach too closely.
A highly social species, Purple Martins are known to roost colonially, with hundreds or even thousands of others, with the largest Purple Martin colony recorded estimated to have over 700,000 birds. Barn Swallows also roost colonially, particularly out of the breeding season, but roosts are relatively small and loose, and nest sites are usually limited to a single bird or a maximum of ten pairs.
Both Purple Martins and Barn Swallows are fully migratory, undertaking lengthy flights between northern breeding grounds and winter territories in the warmer, milder south.
Migration patterns differ, with Barn Swallows having more varied routes and a mix of long and shorter migration journeys. One popular fall migration route takes Purple Martins across the Gulf of Mexico into the Amazon basin, while the species is regularly seen in migration passage across the south-western US and Mexico in the late summer months.
Spring migration brings both species to their breeding grounds between late February and April, and post-breeding departure begins from August onwards, increasing in September and usually complete by early October.
A Purple Martin - Both Purple Martins and Barn Swallows are fully migratory, undertaking lengthy flights
Due to fierce competition for nesting sites, and losing out on suitable cavities to more aggressive species such as Starlings and House Sparrows, Purple Martins are now almost entirely dependent on artificial nesting pods supplied by humans. These pouches are hung on poles in backyards, with several pods located close together to create their naturally preferred nesting colonies.
In contrast, Barn Swallows craft their own nests, often using manmade structures as a foundation on which they build mud cups, on the undersides of ledges, shelves, bridges and in barns, sheds and agricultural outbuildings. Nesting is less colonial than in Purple Martins, although small numbers of Barn Swallows may be found nesting fairly close together.
Purple Martins are cavity nesters, and on the rare occasions they are able to move into an unoccupied Woodpecker cavity and allowed to remain there to raise their young, they will create a cup-shaped nest inside, created by the female from nesting materials such as feathers, soft grasses and twigs supplied by the male. When using artificial nesting pods, a nest is crafted inside the base of the pod, and additional lining is added as a lining.
Barn Swallows’ nests are intricately crafted using wet mud, gathered from river banks and lakes, and bound together using their own saliva. Mud cups are built up using grasses and feathers, with the wet mud drying to form a solid outer shell. Both males and females work together to build impressive constructions.
Purple Martins are now almost entirely dependent on artificial nesting pods supplied by humans
Barn Swallows’ nests are intricately crafted using wet mud, gathered from river banks and lakes, and bound together using their own saliva
Purple Martins and Barn Swallows are insectivores, depending on small flying insects they catch on the wing for food. Both species are highly skilled aerial hunters, with swallows frequently seen skimming over lakes and rivers, open fields, and marshy areas, dipping down for a quick drink as they forage for wetland insects.
Purple Martins’ main prey is flies, moths, mosquitoes, dragonflies and flying beetles, caught at a relatively high altitude while in flight. They rely on their agile flight maneuvers to pursue prey and feed mainly at a height of between 50 m and 120 m (160 ft and 500 ft) above ground.
The diet of Barn Swallows is more varied, including bees, wasps, and ants which it captures when flying particularly close to the ground.
Sound and song are another way in which Barn Swallows and Purple Martins differ and are a reliable way of telling the two species apart.
Purple Martins are notoriously more tuneful than their smaller relatives, using a varied repertoire of whistles, cheerful chirping and upbeat warbling. Males can be heard during the breeding season, making their presence known with loud chattering, while they claim a territory.
Barn Swallows, in contrast, have harsher vocalizations, using sharp, high-pitched calls to communicate and a rapid chatter in flight. These calls are repeated in a continuous pattern and can be heard during courtship, territorial defense and between members of a flock when foraging or migrating.
The diet of a Barn Swallow includes bees, wasps, and ants which it captures when flying particularly close to the ground
Both Purple Martins and Barn Swallows are relatively secure and face no current or urgent threats to population numbers or the future survival of their species. Globally, both species are classified as of least concern. However, ongoing conservation initiatives and land management schemes can help to prevent any changes to their long-term survival.
Changes in land use and habitat loss are more of a concern for Barn Swallows, which nest and feed in more open areas than Purple Martins, which already thrive in areas with human settlement. Chemical-free farming processes are vital in supporting the survival of barn swallows, which forage extensively on farmland for insects. Cultivated land where pesticides have been used can lead to swallows eating contaminated prey, which can prove fatal.
For Purple Martins, competition for nest sites from invasive species has caused a significant change in nesting practices, and it’s vital that enough human-supplied nesting pods or gourds are available, and that existing nesting pouches are maintained and safe to use.
There are an estimated 290 to 487 million barn swallows in the world, while purple martins are far less common, due to their more limited distribution range, numbering around 9.3 million individuals.
Despite some similarities in feeding habits and behavior between Purple Martins and Barn Swallows, there are also many distinct differences which should help you to confidently tell the two species apart, both at close range and when passing overhead. You should now be able to make a fair guess as to which species’ aerial acrobatics you’ve just witnessed in the sky by a quick look at its tail shape, body size and coloring.
Whichever species you’ve spotted, their aerobatic antics are certainly always an awesome sight, signaling the start of summer and reminding us of the incredible migration journeys they undertake to reach our skies.
Purple Martins have stocky bodies, with a broad wingspan and their forked tail is slightly rounded
Barn Swallows are smaller, and more streamlined with slimmer wings and long trailing tail forks than Purple Swallows
The main differences between Barn Swallows and Purple Martins are in size, shape, plumage and distribution range. Barn Swallows are smaller and more streamlined with slimmer wings and long trailing tail forks. Purple Martins are sturdier, larger birds, with broad wings and less prominent tail forks.
Purple Martins are darker in color, with males a blackish-purple all over, while females have duskier gray underparts. Barn Swallows have red faces, blue backs, whitish breasts, bellies and underwings.
If you’re not sure if the bird you’ve spotted is a Purple Martin or a Barn Swallow, your location could also prove to be the key.
Purple Martins are confined to the eastern regions of North America in the summer, migrating to northern South America in the fall.
Barn Swallows are widespread across the world, found in North America, Europe, and northern Asia in the summer months, and heading to southern Africa, South America, South Asia and northern Australia once breeding is complete.
Barn Swallows have longer, more streamlined tails and are slimmer with more pointed wings. Purple Martins are larger and chunkier, with shorter, more rounded tail forks.
Location is also key. Barn Swallows are widespread across the Americas, Europe, Asia, southern Africa and northern Australia, while Purple Martins are strictly limited to North and South America.
Spring and early summer are the best times for seeing Barn Swallows in North America and Europe, with arrivals early in the breeding season common from as early as February in California and Texas, but more commonly from April in the rest of the United States and in the UK.
By late August, most have already completed breeding and will be forming migratory flocks ahead of departing south between September and October. In Australia, the reverse is true, with arrivals from August onwards, and departures until March.
Purple Martins can be seen across the eastern United States from late June until August, with numbers peaking in mid-July.
Purple Martins and Barn Swallows are both migratory species and there is some overlap between their migration routes and their range in North and South America.
However, the two species usually have different breeding and nesting habitats and preferences, and although it may be possible to encounter them in similar regions during migration, it’s not likely you’ll find them nesting side by side.
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