The chief difference between adult male and female ivorybills lies in the crest, which in the male is a brilliant scarlet, not including the uppermost feathers, which are black, like the top of the head, while the somewhat recurved crest of the female is entirely black. Females average somewhat larger than males in most of their measurements, except those of bill and feet, as the following figures (length in millimeters) given by Ridgway (1914) for 15 males and 11 females indicate: ADULT MALES: Skins, 420-493 (454); wing, 240-263 (255.8); tail, 147-160.5 (154.4); culmen, 63-72.5 (68.2); tarsus, 42.5-46 (44.2); outer anterior toe, 30-34 (32.1). ADULT FEMALES: Skins, 452-488 (471); wing, 240-262 (256.4); tail, 151-166 (159.5); culmen, 61-67.5 (64.3); tarsus, 40.5-44 (42.6); outer anterior toe, 30-33.5 (31.7). In both sexes the general color is a glossy blue-black, with the tail and primaries duller or with the gloss less distinct. A narrow stripe on each side of the neck, starting below the eye and continuing down to the folded secondaries, is conspicuously white, as are also the secondaries, all but five or six of the outermost primaries, and the under wing coverts. The white nasal plumes and anterior edges of the lores more or less match the ivory-white bill and help to emphasize its size. The iris is pale, clear lemon-yellow in both sexes, and the tarsi and toes are light gray. _Food._--Audubon (1842) mentions grapes, persimmons, and hackberries as food of the ivorybills in addition to beetles, larvae, and large grubs. McIlhenny, in his communication to Bendire (1895), mentions their feeding on acorns, but Maurice Thompson (1885) asserts that “it is only woodpeckers which eat insects and larvae (dug out of rotten wood) exclusively.” Allen and Kellogg (1937) report: We were never able to follow a bird continuously through the forest of either Louisiana or Florida for more than an hour before it would make a long flight and we would be unable to find it again. Ordinarily upon leaving the nest-tree or its immediate environs the bird would fly at least a hundred yards before stopping. Then it would feed for from a few minutes to as long as half an hour on a dead tree or dead branch before making a short flight to another tree. It might make a dozen such short flights and then, without any warning and for no apparent reason, it would start off on a long flight through the forest that would take it entirely out of sight.