Purple Martin or Tree Swallow?
Here's how to tell the difference
Purple Martin
Tree Swallow
Purple Martin
Progne subis
General appearance
The purple martin is our largest swallow, measuring approximately 7-8 1/2 inches (18-22 cm). The bird features angular, pointed wings and a distinctive forked or notched tail. Its size is comparable to a robin or sparrow, and it sports various colors including black, blue, grey, purple, and white.
Male vs female
Sexual dimorphism is present in purple martins. Males exhibit a glossy blue-black coloration all over their bodies. Females, on the other hand, are relatively greyer, especially on the bottom part, and they have a white belly. So, if you spot a martin with a white belly, it is most likely a female.
Juvenile
Young purple martins share the same features with the adult females, they are grayer below and have white bellies. As they mature, males will develop their glossy blue-black plumage.
Size
7.7 - 8.1 in/1.6 - 2.0 oz
There's more to learn about Purple Martin
View full detailsTree Swallow
Tachycineta bicolor
General appearance
The tree swallow measures between 5 to 6 1/4 inches or 13-16 cm. It displays a sharp contrast in colors between the top and bottom, with dark above and clean white below. Its wing shape is broad, long, pointed and tapered. The tail shape is notched and square-tipped.
Male vs female
The adult males and females of tree swallows have distinctive colorations. The adult males are glossy blue or green above, with a dark cap that extends down to the eye level. The females might show similar coloration, although possibly less glossy.
Juvenile
Juvenile tree swallows display a different coloration from adults. They are dusky brown above and often have a gray-brown wash across their chest. This is unlike the Bank Swallow, which exhibits a more prominent marking on the chest. With time, the juveniles' color changes to resemble those of the adults.
Size
4.7 - 5.5 in/0.6 - 0.8 oz
There's more to learn about Tree Swallow
View full detailsHow to tell the Purple Martin from the Tree Swallow
Visual differences
The Purple Martin is noticeably larger, measuring about 7.5-8.5 inches, compared to the smaller Tree Swallow at 5-6.25 inches. Male Purple Martins have glossy blue-black plumage, while male Tree Swallows are glossy blue or green above with a sharp contrast of white below. The Tree Swallow’s tail is notched and square-tipped, while the Purple Martin's tail is forked. Female Purple Martins are gray with white bellies, whereas female Tree Swallows have less glossy coloration similar to males. The Purple Martin has a more robust body compared to the slender Tree Swallow.
Key differences and behavior
Purple Martins and Tree Swallows are both aerial insectivores but differ in their social and nesting behaviors. Purple Martins are highly social, forming large colonies and using human-provided nest boxes, especially in the east; they also engage in communal breeding and often return to established colonies. In contrast, Tree Swallows are more solitary in breeding, forming a new pair bond each season and nesting in natural or artificial cavities without the same colonial preference. Purple Martins primarily consume flying insects, while Tree Swallows have a more varied diet, including plant material, notably bayberries in winter. Habitat-wise, both prefer open areas near water, but Purple Martins are more often seen in human-altered environments, while Tree Swallows can be found in natural marshes and meadows. Both species engage in high-frequency feeding of their young, though Tree Swallows notably feed nestlings thousands of insects daily.
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