Northern Rough-winged Swallow
The Northern Rough-winged Swallow’s name often begs the question, “What is so rough about this bird’s wing?”
Length: 5.5 inches
Wingspan: 14 inches
Weight: 0.56 ounce (16 grams)
AOU code: NRWS
By Andy McCormick
The answer is the first primary wing feather.
The male has small, stiffened barbs extending from the leading edge of the wing, each barb with a hook that bends toward the body.
The female’s wing also has barbs, but without hooks (De Jong). The detail drawing at right shows the difference.
The barbs cannot be seen in the field. No one seems to know what purpose the barbs serve.
(Illustration: Birds of North America. “Rough” primary feathers of male and female Northern Rough-winged Swallow. Actual spacing between barbs is approximately 0.25 mm.)
It's All About the Barbs
Both the bird’s genus and species names refer to the barbs on the wing. The Northern Rough-winged Swallow is in the genus Stelgidopteryx, scraper wing, from the Greek stelgis, a scraper, and pterux, the wing of a bird.
The species name is serripennis , saw-winged, from the Latin serra, a saw, and penna, a wing (Holloway).
It was virtually by accident that John James Audubon discovered the Rough-winged was a distinct species. In 1819 he collected a group of swallows, all of which he thought were Bank Swallows. When he examined them, he found he had birds of a species previously unknown to European scientists.
Like Bank Swallows, Rough-winged Swallows nest in holes in stream banks, trees, or human-made structures.
However, they do not always burrow their own holes and will use abandoned holes of other birds or animals (Kaufman).
Rough-wings like to nest near running water and are typically solitary nesters, but several pairs may join together in a favorable site (Kaufman).
Typically four to seven plain white eggs are deposited, with incubation lasting about two weeks. Both parents feed the young, which leave the nest after three weeks.
Like a Bank Swallow, But Different
Rough-wings are similar in plumage and habitat to Bank Swallows. Both species nest in stream banks and both have brown backs.
In flight the Rough-wing is uniformly brown across the wings and back, whereas the Bank Swallow’s wings are darker than the back.
The Rough-wing has a gray chest, and the Bank Swallow has a sharp brown band across the chest.
On the Rough-wing the undertail coverts are white. These undertail feathers become more prominent in flight and are spread with some flare by the male during courtship.
Photo: Northern Rough-winged Swallow, by Dan Streiffert
Rude, or Just Rough?
Northern Rough-winged Swallows are often identified by voice as they fly close to the surface of the water or field. They have a fairly distinctive call among swallows: They vocalize in short bursts of a series of low-pitched brrrt sounds. This flight call can be described as similar to the sound of giving the other birds the raspberry. Hear the Rough-wing’s call at the Macaulay Library.
The population of the Northern Rough-winged Swallow is stable and may be increasing. Once limited to natural nest sites in stream erosion banks and natural cavities, the species has adapted to civilization and will nest in cavities such as culverts, drainpipes, and crevices and in holes in walls, wharves, bridges and semitrailers (De Jong).
See Them April to August
The migration pattern of Northern Rough-winged Swallows is described as leisurely, with birds of the eastern flyways moving a few days ahead of those in the west during spring migration (De Jong). Pacific Flyway birds arrive in Washington in mid-April.
Fall migration begins in August, when Rough-wings move southward in small groups and sometimes in mixed flocks with other swallows. They are diurnal migrants and will stop to forage as they move along. Wintering grounds are in Central American countries.
For references, please email Andy McCormick: email@example.com.