Part 2
Audubon further states: “The average diameter of the different nests which I examined was about 7 inches within, although the entrance, which is perfectly round, is only just large enough to admit the bird.” Beyer (1900) says: “The entrance measures exactly 4½ inches in height and 3⅞ inches in width,” and McIlhenny (Bendire, 1895) gives the measurements of a typical hole as “oval and measures 4⅛ by 5¾ inches,” and Scott (1888) as “3½ inches wide and 4½ inches high.” The corresponding measurements of the nests of Pileated Woodpeckers are given by Bendire (1895) as follows: “The entrance measures from 3 to 3½ inches in diameter, and it often goes 5 inches straight into the trunk before it is worked downward.” The additional one to two inches in diameter of the nest hole should be kept in mind when searching for reasons why the Ivorybill has proven less successful than the Pileated Woodpecker in its struggle for existence. Thompson (1885) states: “The depth of the hole varies from three to seven feet, as a rule, but I found one that was nearly nine feet deep and another that was less than two.” He also claims that they are always jug-shaped at the lower end.
Of two nests discovered by Hoyt (1905) in Claremont County, Fla., one was 58 feet up in a live cypress about 20 yards from a nest discovered in 1904 by the Brown brothers; the second nest built by the same pair after the first eggs had been taken was in a cypress stub about 70 yards distant from the first and 47 feet from the ground. The opening of the first nest was 6¾ inches by 3¼ inches, with the trunk of the tree 15 inches in diameter at the nest cavity, which was 14 inches deep. The second nest hole measured 6 by 3¾ inches and was likewise 14 inches deep. “The opening in both nests was uneven and rough, and just inside the hollow was much enlarged, being 9 inches across, and unlike the nests of other woodpeckers, was smaller at the bottom than at the top. * * * One marked feature of the nest tree of which I have seen no mention made is that the outer bark of those I have examined was torn to shreds from a point some distance below the nest site to 15 or 20 feet above it. This made the nest tree noticeable for quite a distance. The last nest taken this season had little of this work done.”
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.”
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.
Frequently they return again and again to the same tree until they have entirely stripped it. At one time we thought this was their chief method of feeding, but we have since watched them digging for borers exactly like hairy or pileated woodpeckers. At one time we watched the female working at a deep gash in the tall stub of a dead gum, which was apparently a favorite feeding place. She clung to the spot for about five minutes, occasionally picking hard, but never chipping off any large flakes that would account for the depth of the hole which was exactly like that made by pileated woodpeckers,--about four inches deep and eighteen inches long. Finally she flew and disappeared in the direction of the nest which was about two hundred yards away. In a few minutes the male ivorybill came to the same spot where the female had been working and he, too, picked at the hole and stayed there for several minutes. At the time we decided that either the ivorybills or perhaps the pileateds had made the gash in the tree for carpenter ants and that the ivorybills were returning each time for more ants. Since the stub was rather rotten and full of woodpecker drillings, we decided to cut it down the next day and make certain of what the ivorybills were securing. Upon examining the hole made by the birds there was, however, no evidence of carpenter ants, and the deep gash followed the tunnels of large, wood-boring beetle larvae (Cerambycidae) of which there were a great many in the tree; the only other available woodpecker food was termites of which there were comparatively few.
Certainly the ivorybills did not do enough digging while we were watching them to uncover any additional borers, so they may have been picking up such termites as appeared in the gash. The birds, while we watched them in Louisiana, divided their time between dead branches of live trees and completely dead trees, but more time was spent knocking off the bark for whatever could be found immediately beneath it than was spent digging deeply for borers. The forest was made up primarily of oak, gum and hackberry, and the woodpeckers showed no preference for species so far as we could determine. In Florida, while the nest was located in a cypress swamp in a live cypress tree, the birds apparently did most of their feeding in the dead pines at the edge of the swamp, scaling off the bark of those small and medium-sized pines that had been killed by fire, or actually getting down on the ground like Flickers, as already described.
The ivorybills are, therefore, apparently somewhat adaptable in their food and feeding habits, but forests of mature trees with their dying branches seem to give them the best habitat for securing their food. The fruits of these trees may likewise add considerably to their attractiveness. The only definite stomach analyses published are of two birds examined by the United States Biological Survey, and reported upon by Beal (1911): “One stomach contained 32 and the other 20 of the wood-boring cerambycid larvae, which live by boring into trees. These constituted 37.5 per cent of the whole food. The remainder of the animal food consisted of engraver beetles (_Scolytidae_) found in one stomach. Of these, three species were identified--_Tomicus avulsus_, _T. calligraphus_, and _T. grandicollis_. The total animal food amounted to 38.5 per cent. The vegetable food consisted of fruit of _Magnolia foetida_ in one stomach, and of pecan nuts in the other. The average for the two was 61.5 percent.”
The ivory-billed woodpecker is represented in the Biological Survey’s collection by the stomachs of three birds. Two of these were males collected on November 26, 1904, at Tarkington, Tex., by Vernon Bailey, and the third was shot at Bowling Green, West Carroll Parish, La., on August 19, 1903, by E. L. Moseley.
The first two stomachs were well filled, and though only the content of the third was received it was apparently well filled also. This last stomach alone contained a trace of gravel. Forty-six percent of the food was animal in origin, long-horned beetles (Cerambycidae, including _Parandra polita_ and _Stenodontus dasystomus_) comprising 45.33 percent, while the remaining 0.67 percent consisted of 3 different species of engraver beetles (_Tomicus_ spp.). Southern magnolia seeds (_Magnolia grandiflora_) formed 14 percent of the vegetable food, hickory (_Hicoria_ sp.) and pecan (_Hicoria pecan_) nuts formed 27 percent, and poison ivy (_Rhus radicans_) equaled 12.67 percent. Fragments of an unidentified gall formed 1 percent of the content.
_Behavior._--The uniform direct flight of the ivorybill resembles that of the red-headed woodpecker more than it does the swooping undulating flight of the pileated, and this general resemblance is emphasized by the large amount of white in the wings. When viewed from below, the long pointed tail is quite conspicuous and the wings seem very narrow because the black portion is so much more conspicuous than the white, which apparently cuts off the whole rear of the wing. This is perhaps not so conspicuous when viewed from the side, but even so it is remarkable how ducklike the bird can appear as it flies swiftly and directly up a lagoon, so much so in fact that certain Louisiana hunters have told me that they have even shot at them under such circumstances, mistaking them for ducks. In this connection Audubon’s (1842) description of the flight of the ivorybill is quite misleading: “The flight of this bird is graceful in the extreme, although seldom prolonged to more than a few hundred yards at a time, unless when it has to cross a large river, which it does in deep undulations, opening its wings at first to their full extent and nearly closing them to renew the propelling impulse. The transit from one tree to another, even should the distance be as much as a hundred yards, is performed by a single sweep, and the bird appears as if merely swinging itself from the top of the one tree to that of the other, forming an elegantly curved line.”
_Voice._--Concerning the voice of the ivorybill there seems to be considerable agreement in that the ordinary note sounds like a single blast from a tin trumpet or a clarinet. In the words of Audubon, “Its notes are clear, loud, and yet rather plaintive. They are heard at a considerable distance, perhaps half a mile, and resemble the false, high note of a clarinet.” According to Hoyt (1905): “It is a single note and resembles the word Schwenk, at times keyed very high, again soft and plaintive, it lacks carrying capacity and can rarely be heard over 100 yards on a still morning, while the harsh notes of the pileated woodpecker can be heard a full mile.” Allen and Kellogg (1937) state that anyone can produce the sound very accurately by using only the mouthpiece of the clarinet. They question whether the loudest calls can be heard half a mile:
It is doubtful, however, if the loudest calls can be heard, under normal conditions, for a quarter of a mile, and some of the weaker ones are scarcely audible at 300 yards. However, when we tested the carrying power of one of our recordings of the common alarm note, _kent_, amplified until it sounded to our ears normal at about one hundred feet, the call was distinctly recognizable at a distance of 2,500 feet directly in front of the amplifier with no trees or buildings intervening. At a 45-degree angle the sound was not recognizable at half this distance. The birds are so often quiet for such long periods that we can scarcely agree with Audubon’s statement that “the bird spends few minutes of the day without uttering them.” They seem much more likely to call when they are alarmed, as when they discover an intruder in their haunts. Both birds give the call, but that of the female is somewhat weaker. In addition to this _kent_ note, as it is called by the natives of Louisiana, and because of which they call the birds “Kents,” they have a variety of low conversational notes when they exchange places at the nest, which are suggestive of similar notes of the Flicker; but they never, so far as we know, give a call at all similar to the _pup-pup-pup_! of the pileated, nor have we ever heard them sound a real tatoo like other woodpeckers, such as described by Thompson (1885), and which McIlhenny (Bendire, 1895) compares to the “roll of a snare drum.” The birds in Florida and all those in Louisiana telegraphed to each other by single or double resounding whacks on the trunk or dead branches. Mr. Kuhn who has had years of experience with them, likewise has never heard any notes or tatoos that were comparable with those of the Pileated. Our observations agree with Audubon’s, rather than with those of some others, in that “it never utters any sound while on the wing.”
Tanner (MS.) reports, however, that in his studies during 1937 he occasionally heard a rapid succession of “kents” given on the wing as one bird flew in to join another.
The calls of the two large species of woodpeckers are so distinct that they should not be confused with each other or with those of any other birds. The fact, however, that ivorybills are continually being reported, even from the Northern States, indicates how unobservant many people are and how necessary it is to stress even such conspicuous differences as those mentioned above.
_Winter._--Ivory-billed woodpeckers are apparently not only nonmigratory but also sedentary and perhaps spend their entire lives within a few miles of the spot where they were hatched. At least, once a pair has established a territory it seems to cling to that area winter and summer, and Tanner (MS.) reports one pair using the same roosting hole in December that they used the preceding April. These territories are doubtless several miles in diameter, but the tendency was for the birds to build up small communities in certain areas until in former years, when their distribution was normal, they were reported as fairly common by observers who happened upon one of these communities. On the other hand, there were perhaps always large areas of similar timber uninhabited by them, so that with equal truth by equally competent observers they were called extremely rare. How much farther they range during the winter than during the nesting season has not yet been worked out, but doubtless the area covered at such times is considerably larger, and this accounts for sporadic records of birds in the nonbreeding seasons in areas where no nests have been located and where no one has been able to find the birds subsequently.