Bird of the Month: Northern Rough-winged Swallow
By Andy McCormick
PC: Joshua Pelta-Heller/Audubon Photography Awards (Northern Rough-winged Swallow)
Scientific Name: Stelgidopteryx serripennis
Length 5.5 in
Wingspan 14 in
Weight 0.56 oz
AOU Band code NRWS
The Northern Rough-winged Swallow’s name often begs the question, “What is so rough about this bird’s wing?” The answer is the first primary wing feather. The male has small recurved hooks at the end of stiffened barbs along the leading edge of the wing. In females the barbs are extended but straight (De Jong). The hooks on the wing are reflected in both the bird’s genus and species names. It 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). See the detail drawing below to see the difference. The barbs cannot be seen in the field.
John James Audubon discovered them in 1819 virtually by accident. He collected a group of swallows, all of which he thought were Bank Swallows, only later to find when he examined them, that 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 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 4-7 plain white eggs are deposited with incubation lasting about two weeks. Both parents feed the young which leave the nest in another three weeks.
The migration pattern of Northern Rough-winged Swallows is described as leisurely with eastern flyway birds a few days ahead of Pacific flyway birds during spring migration (De Jong). They arrive in Washington in mid-April. Fall migration will begin in August and these swallows will 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.
Rough-wings are similar in plumage and habitat to Bank Swallows. Both species nest in stream banks and both have brown backs. The Rough-wing however has a gray chest and the undertail coverts are white. These undertail feathers become even more prominent in flight and are spread with some flare by the male during courtship. In flight they are uniformly brown across the wings and back. In contrast, Bank Swallows have a sharp brown band across the chest and in flight the wings are darker than the back.
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. You can hear their 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 holes in walls, wharves, bridges and semitrailers (De Jong).