Allen and Kellogg (1937) say further:
According to McIlhenny (Bendire, 1895) the female does all the work of excavation, requiring from eight to fourteen days, while the male sits around and chips the bark from neighboring trees. Audubon, however, states that “both birds work most assiduously at this excavation, one waiting outside to encourage the other.” Maurice Thompson (1896) likewise reports that both birds work at the excavation. We had no opportunity to check either statement but certainly both birds take part in incubation and feeding the young. The chips are not removed from the vicinity of the nest for each one that we have examined has had piles of chips directly below the opening though, since most of the trees were standing in water, the chips were not very conspicuous.
We camped within three hundred feet of our first Ivorybill nest in Louisiana, in 1935. A pair of 24-power binoculars set on a tripod was trained on the nest opening, and from daylight, April 10, until 11 a. m., April 14, continuous observations during the hours of daylight were made either by the writers or by James Tanner. The nest had been found the morning of April 6, when the female was incubating, but how far along incubation had proceeded we made no effort to determine for fear of disturbing the birds. Contrary to most published accounts, however, the birds were not particularly wary and soon became so accustomed to our presence that they would enter the nest-hole with one of us standing at the base of the tree and later even when one of us was descending from a blind which we built on April 9 in the top of an adjacent rock elm, twenty feet distant from the nest. On April 9, we located a second pair of Ivorybills in the vicinity of a fresh hole about fifty feet up in a dead oak, some two miles to the south of the nest in the maple. The following morning, however, the nest was occupied by a black squirrel and the birds had disappeared.
Briefly summarizing our five-day vigil at the occupied nest, we learned that the birds took turns sitting on the eggs, working in approximately two-hour shifts when not alarmed, but changing places more frequently when disturbed. Activities usually commenced about six o’clock in the morning, three-quarters of an hour after Cardinals and Carolina Wrens started singing. At this time the female relieved the male after his having spent the night on the eggs. Activities ceased about four o’clock in the afternoon when the male relieved the female on the eggs and went in the nest for the night. This was nearly three hours before dark, which came about seven o’clock.
Eggs.—According to Bendire (1895):
The eggs of the Ivory-billed Woodpecker are pure china white in color, close grained, and exceedingly glossy, as if enameled. They vary in shape from an elongate ovate to a cylindrical ovate, and are more pointed than the eggs of most of our Woodpeckers. They appear to me to be readily distinguished from those of the Pileated Woodpecker, some of which are fully as large. From three to five eggs are laid to a set, and only one brood is raised in a season. * * *
The average measurement of thirteen eggs is 34.87 by 25.22 millimetres or about 1.37 by 0.99 inches. The largest egg measured 36.83 by 26.92 millimetres, or about 1.45 by 1.06 inches; the smallest, 34.54 by 23.62 millimetres, or about 1.36 by 0.93 inches.
The eggs described by Hoyt (1905) measured 1.46 by 1.09 and 1.43 by 1.07 inches in the first set and 1.43 by 1.10 and 1.43 by 1.08 inches in the second set.
From my own experience and the observation of others, it seems to me that the number of eggs laid by the ivorybill would not normally exceed three, and one or two of these are often infertile. Frequently, if the bird is successful in rearing any offspring at all, a single youngster is the result rather than two or three. Allen and Kellogg (1937) describe three nests in which no young were successfully reared, although at least some of the eggs apparently hatched, while Scott (1888), Beyer (1900), and Tanner (1937 and 1938 MS.) each report single young, and in the type set of three eggs (Ralph collection, Lafayette County, Fla.) two were infertile, and both of Hoyt’s sets contained two eggs each. On the other hand, J. J. Kuhn reports seeing one pair of ivorybills with four young in 1931 and again in 1936 in the same forest where Allen and Kellogg made their studies. In 1932, 1933, and 1934 he observed a pair of ivorybills with two young.
Plumages.—So far as I have been able to find, no one has ever published a description of the natal or juvenal plumages of the ivory-billed woodpecker. The probability is that natal down is absent, although. Scott (1888), who found a nest containing one young in Florida March 17, 1887, says: “The young bird in the nest was a female, and though one-third grown had not yet opened its eyes. The feathers of the first plumage were apparent, beginning to cover the down, and were the same in coloration as those of the adult female bird.”