Figure 1. The characteristic white wing-patch is hardly visible in this individual (compare with fig. 2), maybe because of worn plumage (or molting?). But the white rump is also a help in identification, especially in comparison with the Blue-and-white Swallow Notiochelion cyanoleuca.

White-winged Swallows can often be seen close to water, for example flying over reservoirs, or sitting on a tree-trunk, a few feet above the water-line. I have seen pairs or small groups of Tachycineta albiventer, but never large flocks like those formed by Progne chalybea and others.

Figure 2. The white wing-area, if as conspicious as here, makes identification of the species easy.