Blue-and-white Swallow (Notiochelidon cyanoleuca) Science Article 1
This Swallow has the upper plumage is dark, violaceous steel-blue; the under parts are pure white except for the blue-black under tail-coverts, the grayish-brown sides and flanks, and a few dusky spots in the center of the chest, which are lacking on some individuals. The tail is short and slightly forked. The bill is black, the eyes brown, and the feet dark. The sexes are alike in appearance.
ALEXANDER F. SKUTCH, The Auk 59(2)392-406