Catesby Volume I: The Swallow-Tail Hawk
Description of The Swallow-Tail Hawk
ACCIPITER cauda furcata
It weighs fourteen ounces; the Back black and hooked, without angles on the sides of the upper Mandible, as in other Hawks; the Eyes very large, and black, with a red Iris: the Head, Neck, Breast and Belly white; the Upper-part of the Wing and Back, dark purple; but more dusky towards the lower parts, with a tincture of green; the Wings long, in proportion to the Body; they being extended, are four foot; the Tail dark purple, mix?d with green, remarkably forked, the utmost and longest feather being eight inches longer than the middlemost, which is the shortest.
Like Swallows, they continue long on the wing, catching, as they fly, Beetles, Flies, and other Insects, from trees and bushes. They are said to prey upon Lizards and other Serpents; which has given them (by some) the name of Snake-Hawk. I believe they are Birds of passage, not having seen any of them in winter.