During April 1937, James Tanner, recipient of the Audubon fellowship at Cornell University for the study of the ivory-billed woodpecker (MS.), was able to follow a young ivorybill for over 3 months after it left the nest, and though he never had the bird in his hands, his description is much more complete than Scott’s and the most accurate one available: “March 10, 1937: The young ivory-billed woodpecker just out of the nest resembled an adult female in general pattern but with the following differences: The black crest was short and blunt; the tail was short and square; the outer primaries were all tipped with white, instead of being wholly black as in the adult; the bill was shorter than that of an adult and was chalky white instead of ivory; the eye was a dark brown or sepia. One month later the crest was long but still blunt and black, the tail was almost as long and pointed as an adult’s, and the eye and bill were beginning to turn color.
“The bird developed gradually from then, until at three and a half months out of the nest (July 14, 1937) its size, proportions, bill, and eye color were the same as those of an adult. By then, scarlet feathers had appeared in the back of the crest. The white wing tips to the outer primaries were almost worn away.”
Since Tanner’s bird began to show red in the crest when it was three and a half months old, it is probable that the postjuvenal molt is completed by early fall and that thereafter young and adults are similar.
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.
Audubon states that “it seldom comes near the ground”; but the birds we have watched behave no differently from pileated woodpeckers in this respect, sometimes working high up in the trees but at other times within five or ten feet of the ground. The female of the Florida pair which we watched for over an hour on a “burn” sometimes got down on the ground around the seared, prostrate trunks of the saw palmettos, hopping like a Flicker, while her mate stayed on the trunks of the pines five to ten feet up. We never saw the Louisiana birds on the ground but there was plenty of evidence, both in Florida and Louisiana, that a bird will continue scaling the bark from recently killed trees for the beetle larvae beneath, clear to the base of the tree, until the tree stands absolutely naked with the bark piled around its base.