Swallow-tanager

What is Swallow-tanager?

The Swallow-tanager (Tersina viridis) is a bird native to northern South America and is the only member of the subfamily Tersininae within the family Emberizidae, though some experts classify it in its own family, Tersinidae.¹

Measuring approximately 15 cm (6 inches) in length, the bird exhibits physical characteristics of both a tanager and a swallow, featuring long wings and a swallowlike bill. The species displays sexual dimorphism: males are light blue with black markings, while females are primarily green.¹

Swallow-tanagers are unique in their feeding habits, as they catch insects while in flight and consume large fruits by storing the pulp in throat pouches and ejecting the seeds. They typically nest in crevices found in walls, sandbanks, or tree holes.¹

How does the Swallow-tanager’s diet compare to other tanagers?

While both the Swallow-tanager and other tanagers consume fruit and insects, their feeding strategies differ significantly.

Most tanagers are arboreal birds that primarily inhabit treetops, undergrowth, or shrubbery, where they forage for fruit—a major component of their diet—and occasionally insects. In contrast, the Swallow-tanager exhibits specialized behavior similar to swallows, catching insects on the wing.¹²

Furthermore, the Swallow-tanager has a unique method for processing large fruits: it stores the pulp in specialized throat pouches and ejects the seeds. While many birds consume fruit, seeds, or nectar as high-value food sources, the Swallow-tanager’s combination of aerial insectivory and specific fruit-processing anatomy distinguishes it from the broader group of tanagers, which generally possess bills adapted for more conventional foraging.²¹³

Why is the Swallow-tanager considered the sole member of its subfamily?

The Swallow-tanager (Tersina viridis) is considered the sole member of the subfamily Tersininae because it possesses a unique combination of morphological and behavioral traits that distinguish it from other members of the family Emberizidae.¹

While it shares some superficial similarities with tanagers, such as its general size and presence in the Americas, its specialized anatomy—including long wings and a swallowlike bill—and its distinct feeding behavior of catching insects on the wing set it apart from the more typical arboreal tanagers. Due to these evolutionary and physical differences, some ornithologists argue that the species is sufficiently distinct to warrant its own family rank, known as Tersinidae.¹²

What are the main differences between male and female Swallow-tanagers?

The male and female Swallow-tanager exhibit distinct sexual dimorphism in their coloration:

• Male: The male is characterized by a light blue plumage accented with black markings.¹
• Female: The female is primarily green in color.¹

Beyond these visual differences, both sexes share the same physical structure, including a length of approximately 15 centimeters (6 inches), long wings, and a specialized swallowlike bill used for catching insects on the wing and consuming fruit.¹