This chunky swallow is readily recognized by its square tail and orangish rump patch. It nests colonially and has taken to human-made structures so well that it has greatly expanded its range into many areas otherwise not suitable for it. It does not do well in urban settings, however, and quickly disappears when areas become densely settled. The unique gourd-shaped mud nest is often usurped by other species for nesting and is often used for protective roosting sites by rosy-finches and other wintering species.
It is a locally common to abundant breeding bird near water throughout most of Oregon. Its largest colonies occur on cliff faces along waterways east of the Cascades.