Northern Rough-winged Swallows are one of the plainer swallows found in Oregon, often identified by their unassuming brown plumage. Unlike some of their more brightly iridescent relatives, distinguishing between male and female Northern Rough-winged Swallows by sight alone is very difficult, as their plumages are remarkably similar.

General Appearance (Both Sexes):
Size and Shape: Medium-sized swallows, around 4.7-5.9 inches (12-15 cm) long, with long, pointed wings and a relatively square or only slightly notched tail. They have a small head and bill.
Color Pattern: They are uniformly dull brown on their upperparts (head, back, wings, and tail). Their underparts are dingy grayish-brown on the throat and breast, gradually fading to a dull white on the belly and undertail coverts. There is no sharp contrast between the throat/breast and the belly, giving them a generally "smudged" or "unpatterned" look on the underside.
Flight: They have a characteristic slower, more deliberate, and less erratic flight compared to some other swallows. They often fly low over water bodies, fields, and along riverbanks, where they glean insects from the air.
Habitat: In Oregon, they are typically found near water bodies, especially rivers and lakes with high, sandy banks suitable for nesting burrows. They will also use crevices in bridges, culverts, and other human-made structures.
"Rough Wing": Their name comes from tiny, stiff, hook-like barbules on the leading edge of their outermost primary flight feathers. These can only be felt when the bird is held in the hand and are not visible in the field.

Male Northern Rough-winged Swallows:
Plumage: Males and females look virtually identical in their adult plumage. There are no consistent visual differences in coloration or pattern that reliably distinguish a male from a female in the field.
In-hand differences: The "rough" quality of the wing feathers is slightly more pronounced in males, which is a method used by bird banders to determine sex when the bird is caught. This is not a field mark.
Behavioral cues: During courtship, the male may display the white feathers under his tail prominently as he flies after the female. Males are also often heard giving their characteristic "brrrt" call around nesting sites.

Female Northern Rough-winged Swallows:
Plumage: As with males, females have the same overall dull brown upperparts and dingy grayish-brown to dull white underparts. They are visually indistinguishable from males in typical field observations.
Brood Patch: During the breeding season, females will develop a brood patch (a featherless, vascularized area on their belly) for incubating eggs, which can only be seen when the bird is handled.

Key Challenges for Identification and Sexing in Oregon:
Lack of Sexual Dimorphism: The primary challenge is that Northern Rough-winged Swallows are one of the few swallow species where males and females have essentially identical plumages.
Confusion with Bank Swallows: They can sometimes be confused with Bank Swallows, which are smaller and have a distinct dark brown breast band separating a clean white throat from a white belly. Northern Rough-winged Swallows lack this sharp breast band and have a more washed-out throat and breast.
Juveniles: Juvenile Northern Rough-winged Swallows look very similar to adults but may have a faint cinnamon wash on their throat and indistinct cinnamon edges on their upperpart feathers, especially on the wings.