Wildlife Profile


Northern Rough-winged Swallow (Stelgidopteryx serripennis)
by Mark Johns

   Wild Facts about the Northern Rough-winged Swallow

This brown-backed, dusky throated swallow prefers open areas and nests singly or in small colonies in burrows or crevices, including human-made structures. John James Audubon discovered the Northern Rough-winged Swallow in 1819, mostly by accident when he collected what he thought were Bank Swallows in Louisiana. It was only later open closer inspection that he realized he had actually collected a different species. This swallow’s most distinguishing characteristic is its "rough" primary feather, from which its common name has been derived. Although it is rather common throughout its breeding range, it is a bird that is easily overlooked.

History and Status

This bird is a common summer resident throughout the state. Local abundance varies depending on availability of suitable nesting sites for this neotropical migrant. Neotropical (New World) migratory birds breed during summer in temperate North America, migrating north each spring from wintering areas, then fly back south to spend the bulk of the year in Mexico, Central or South America, or the Caribbean.The Northern Rough-winged Swallow is an aerial forager that flies at low-elevation over fields and along narrow gullies and other irregular terrain. It feeds over water more than most other species of swallows and will even pick floating insects from the surface of the water. Its range appears to be expanding, most likely due in part to improved documentation. Breeding in the coastal counties of North Carolina has been observed since the early 1980’s.

There have been significant density increases in the eastern and central regions according to the Breeding Bird Survey (BBS) between 1965 and 1979. It is important to

note that a potential nonbreeding floating population is often not reflected in unts of breeding pairs. BBS data between 1965 and 1979 show that of all the North American swallows, this species has the fewest individuals counted per successful route (routes where Northern Rough-winged Swallows were observed). The species increased very slightly overall from 1966-1989, but there was a significant decrease from 1988-1989.

Description

This small swallow is brown above and dull to creamy white below. There is usually pale grayish-brown on the chest, sides, and flanks. The throat is paler, and sometimes tinged with buff or cinnamon, and the tail is square. Adult males have barbs of the outer web of outermost primary stiffened, free of barbules at the tip and recurved into minute hooklets. The Northern Rough-winged Swallow is distinguished from other swallows that are brown above and white below by a diffuse grayish brown wash on the chest and sides. When seen perched from the front they are fairly easy to separate from the Bank Swallow and young Tree Swallow, but on the wing they can be harder to tell apart. The tone of the upperparts is helpful on low-flying birds. Young Tree Swallows are usually a grayer shade of brown than Bank or Northern Rough-winged Swallows. Bank Swallows often look paler on the lower back and rump, which contrasts with dark wings. Northern Rough-wings tend to look uniformly brown above.

Habitat and Habits

The Northern Rough-winged Swallow is a diurnal neotropical migrant that travels in mixed species flocks, tracking available aerial insects. They often migrate over

diversity of habitats and often far from water. Those leaving the United States are trans-Gulf migrants, and adults usually leave the breeding grounds before young of the year. Spring migrants begin showing up in North Carolina in early to mid March. This species breeds over a wide altitudinal range, nesting from sea level to 6,000 feet. Open areas, including open woodlands, are preferred as breeding habitat. This bird is common throughout its breeding range, but its local distribution depends on suitable nest sites. Nest sites are predominantly near rocky gorges, shale banks, stony road cuts, railroad embankments, gravel pits, eroded margins of streams and other exposed banks of clay, sand or gravel. They will also nest in old kingfisher burrows, protruding drainpipes, crevices in brick or stone structure such as dams, bridges or tunnels, gutters and culverts. They often nest near open water, but water may be coincidental with occurrence of suitable nest sites.

This swallow descends to the ground away from the nest burrow only when it is gathering nest materials. It is not at ease on the ground and usually will fly to move even a few feet. In flight, it lacks the fluttery, almost butterfly-like wingbeat of the Bank Swallow, having slower, more deliberate wingbeats. It doesn’t change direction while flying very often. Only the nest cavity and immediate vicinity are actively defended, and favorite perches near the cavity are used as vantage points from which to maintain their territory. This swallow may nest only a few feet from others, but is not as colonial as other swallow species and may nest alone at times.  Flying insects are eaten while on the wing from dawn till dusk. Generally this swallow feeds more over water and at lower altitude over ground than most other swallow species. This bird is very adept at low flight over irregular terrain.

Occasionally it will take items from water surfaces, and may even land to feed on surfaces occurring at high densities. Most of the insects taken are various types of flies, winged ants or wasps, and beetles. This species drinks by dipping the tip of its bill into the water while flying.

Range and Distribution

The Northern Rough-winged Swallow breeds throughout the lower 48 states and extends into portions of southern Canada. There are birds found year-round along portions of the Gulf coast and in Mexico and parts of Central America. This swallow was once considered a single species, the Rough-winged Swallow, that ranged from southern Canada to Argentina. Now, two separate species are recognized: Northern Rough-winged Swallow in North America and the Southern Rough-winged Swallow from Panama to Argentina. As a whole, the taxonomy of the genus Stelidopteryx is uncertain and in need of further study.

The Northern Rough-winged Swallow winters into middle Central America and northern South America. Lives to at least 5 years according to US Fish and Wildlife Service, but few banding records exist.

People Interactions

Individuals are occasionally struck by vehicles, and some nests are flooded due to human caused extremes in water levels in rivers, streams, ponds and reservoirs. Suitable burrows may be a limiting factor in some areas that id sometimes offset by human created cavities like gutters, culverts, drainpipes and crevices or holes in walls, bridges, etc. This bird is noted for its tolerance of human disturbance in the general vicinity of nesting sites. Much like the Bank Swallow, the Northern Rough-winged Swallow likely benefits from growth and expansion of human populations since it has adapted to various human structures and disturbances for nesting.

Suggested Readings

The Birder’s Handbook by Ehrlich, Dobkin, and Wheye, 1988, Fireside Books

A Field Guide to the nests, eggs, and nestlings of North American Birds
, by Harrison, 1984, Collins, London.

The Birdlife of Florida by Stevenson and Anderson, 1994, Univ. of Florida Press

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