Life Histories 

A chapter from the electronic book:  Life Histories of Familiar North American Birds

Ivory-billed Woodpecker
Campephilus principalis (Linnaeus)  

Contributed by Arthur Augustus Allen
[Published in 1939: Smithsonian Institution United States National Museum Bulletin 174: 1 - 12]

The large size and striking color pattern, the mystery of its habitat, and the tragedy of its possible extinction combine to make the ivory-billed woodpecker one of peculiar interest to all Americans who have any pride in the natural resources of their country.

Ever since the days of Mark Catesby (1731) this species has attracted popular attention, and even at that time, as he stated in his Natural History of Carolina, Florida, and the Bahama Islands: "The bills of these Birds are much valued by the Canada Indians, who made Coronets of 'em for their Princes and great warriors, by fixing them round a Wreath, with their points outward. The Northern Indians having none of these Birds in their cold country, purchase them of the Southern People at the price of two, and sometimes three, Buck-skins a Bill." At that time the species was found throughout the Gulf States as far north as North Carolina and up the Mississippi Valley as far as southern Ohio and Illinois.

Today it is almost extinct, and indeed during the past 50 years long periods have elapsed when no individuals have been reported from any part of its range. It apparently has been exterminated from all but a few isolated localities in Louisiana, Florida, and South Carolina, where it still clings on in a precarious position.

The ivorybill is primarily a bird of the "great moss-hung southern swamps," where mature timber with its dying branches provides a bounteous food supply of wood-boring larvae, but its habits apparently vary in different parts of its range, for the birds I observed in Florida, although nesting in a cypress swamp, did most of their feeding along its borders on recently killed young pines that were infested with beetle larvae. They even got down on the ground like flickers to feed among palmetto roots on a recent burn. In Louisiana, on the other hand, the nesting birds observed confined their activities to a mature forest of oak, sweet gum, and hackberry, and paid little attention to the cypress trees along the lagoons.

Spring--At what time the winter groups of ivorybills break up and spring activities commence is rather difficult to state, for there seems to be considerable irregularity to the breeding season. Judged from published records of its nests, the period of greatest activity would seem to be late March and early April. According to Audubon, (1842): "The ivory-billed woodpecker nestles earlier in spring than any other species of its tribe. I have observed it boring a hole for that purpose in the beginning of March." Scott (1881) reports taking an incubating female in Florida on January 20, 1880, and (1888) of finding a nest containing one young female about one third grown on March 17, 1887. Ridgway (1898) likewise speaks of shooting a male that left its nest hole February 15, 1898, and Hoyt (1905) states that "in Florida they begin building the latter part of January, and if undisturbed the eggs are laid by February 10th." In 1937 James Tanner discovered a nest in Louisiana from which the fledgling left on March 30, fully 2 months earlier than any previous records from the same locality, and in 1938 apparently the same pair of birds had young the last week in February. In contrast to these dates we find 10 records of April nesting, 5 for May, and 1 (Beyer, 1900) of a young bird just out of the nest in July. The latter records might well constitute second attempts at nesting. The Florida birds, in general, start earlier than those in Louisiana, but at best there seems to be less regularity to the commencement of the nesting period than is found with most of our North American woodpeckers. In this, the ivorybill may register its affinity with tropical birds in general, the ivorybill being the most northern representative of an otherwise tropical or semitropical genus. There is some evidence for believing that ivorybills wander over considerably larger territories in winter than those to which they confine their activities in the spring, but little definite information has thus far been recorded on any of their before and after breeding activities.

Courtship--Nothing seems to have been written on the courtship of the ivorybill except the observations of Allen and Kellogg (1937):

Our only observations were made in Florida about 6 a. m., on April 13, 1924. We had discovered this pair of Ivorybills at about the same time the preceding morning when they came out of the cypress swamp and preened their feathers and called a few times from the top of a dead pine before going off together to feed. They had made such a long flight the previous day that we were unable to find them again, but that night, still traveling together, they had returned to the same group of medium-sized cypress trees which they had apparently left in the morning and In which there was one fresh hole In addition to four or five other old ones In the near vicinity. On the morning of the 13th, they called as they left these cypress trees and flew to the top of a dead pine at the edge of the swamp, where they called and preened. Finally the female climbed up directly below the male and when she approached him closely he bent his head downward and clasped bills with her. The next instant they both flew out on to the "burn," where we followed their feeding operations for about an hour.

Nesting--As before stated, while there are a few records of February nesting, the most definite records are for March, April, and early May, as follows:

April 6, ____. M. Thompson, Okefinokee swamp, Georgia. Laying.
April 9, 1892. E. A. Mcllhenny, Avery swamp, Louisiana. Three fresh eggs.
April 10, ____. Dr. S. W. Wilson, Altamaha swamp, Georgia. Four eggs.
April 15, 1893. A. Wayne, Florida. A young female about 2 weeks out of the nest.
April 19, 1893. Ralph Collection, Lafayette County, Fla. Three eggs.
May 2, 1892. E. A. Mcllhenny, Avery swamp, Louisiana. Three eggs.
May 19, 1892. E. A. Mcllhenny, Avery swamp, Louisiana. Four eggs, a second laying.
May (early) 1894. E. A. Mcllhenny, Avery swamp., Louisiana. Five young, 3 days old.
May 3, 1885. Capt. B. F. Goss, Jasper County, Tex. Three eggs.
July 1897. George G. Beyer, Franklln Parish, La.
March 4, 1904. Brown brothers (Hoyt), feeding young.
March 16, 1904. H. D. Hoyt, Taylor County, Fla. Large young.
March 4, 1905. H. D. Hoyt, Claremont County, Fla. Two eggs, incubation advanced.
March 24, 1905. R. D. Hoyt, Claremont County, Fla. Two eggs slightly Incubated (second laying of the preceding).
April 13, 1924. A. A. Allen, Taylor Creek, Fla. Nest completed. Incubation not yet started.
April (early) 1931. J. J. Kuhn, northern Louisiana. Incubating.
May 13, 1934. J. 3. Kuhn, northern Louisiana. Probably small young.
April 6, 1935. A. A. Allen and P. P. Kellogg, northern Louisiana. Incubating.
April 9, 1935. A. A. Allen and P. P. Kellogg, northern LouIsiana. Building.
April 25, 1935. A. A. Allen and P. P. Kellogg, northern Louisiana. Incubating.
May 10, 1935. A. A. Allen and P. P. Kellogg, northern Louisiana. Small young.

The site of the Ivorybill's nest seems to vary considerably. Audubon states: "The hole is, I believe, always made in the trunk of a live tree, generally an ash or a hackberry, and is at a great height." There are, however, records of their nesting in live cypress, partially dead oaks, a dead royal-palm stub,"an old and nearly rotten white elm stump," etc., indicating about as great a variety as shown by the pileated woodpecker. The lowest authentic nest of which we have found a record, was that described by Beyer (1900) "about 25 feet up in a living over-cup oak," although Scott (1881) mentions what he considered "an old nest evidently of this species," in a palmetto stub only fifteen feet from the ground. The nest which we discovered in Florida, in 1924, was about thirty feet up in a live cypress and there were other holes in the vicinity in similar trees that had apparently been used in years past. The bark had healed over in some cases and scar tissue was apparently trying to close the wounds. Of the four nests examined in Louisiana, three were in oaks and one in a swamp maple. The maple, seven and a half feet in circumference (breast high), was partially alive, but the top where the nest was located, 43 feet from the ground, was dead and pithy. Of those in oak trees, one was in a dead pin-oak stub about ten feet in circumference and about fifty feet high, standing in more or less of a clearing. The nest was 47 feet 8 inches from the ground. The other two were not measured accurately but were certainly over forty feet from the ground. About the middle of May when it was determined that the first two trees had been deserted, they were cut down, careful measurements taken, and the contents of the holes preserved. The hole in the maple was 5 inches in vertical diameter and 4 1/8 inches laterally, and was slightly irregular at the bottom, as shown in the photographs; that in the oak was more symmetrical with a similar vertical diameter of 5 inches and a transverse diameter of 4 inches. The depth of the maple nest from the top of the entrance hole was 19 1/8 inches, of which 3 inches was filled with chips and "sawdust." This nest cavity was 8 1/8 inches in diameter at the egg level, and the tree itself 18 1/2 inches in diameter at the level of the hole. The nest cavity in the oak was 20 inches from top to bottom with a diameter of 8 1/4 inches at the egg level. The entrance hole went in 3 inches before it turned abruptly downward; the tree at this point was 22 inches in diameter. There was a stub just above the hole in the maple about 4 inches long representing a branch that had apparently died and been broken off years before and started to heal over. The oak was perfectly smooth at the entrance hole, not on either side, slightly above, were the bases of two large branches that could not have given the opening any protection from the weather. The opening in the maple faced north, two of those in the oaks east, and one west. Audubon states: 'The birds pay great regard to the particular situation of the tree and the inclination of the trunk; first, because they prefer retirement, and, again, because they are anxious to secure the aperture against the access of water during beating rains. To prevent such a calamity the hole is generally dug immediately under the juncture of a large branch with the trunk." None of the nests examined by us showed this desire for protection from rain, and the chips at the bottom of the cavity were perfectly dry, though we had had some very heavy rains shortly before they were examined.

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 4 1/2 inches in height and 3 7/8 inches in width," and McIlhenny (Bendire, 1895) gives the measurements of a typical hole as "oval and measures 4 1/8 by 5 3/4 inches," and Scott (1888) as "3 1/2 inches wide and 4 1/2 inches high." The corresponding measurements of the nests of Pileated Woodpeckers are given by Bendire (1895) as follows: "The entrance measures from 3 to 3 1/2 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 he 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 6 3/4 inches by 3 1/4 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 3 3/4 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) 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 ivorybilled 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, 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).

Food--Audubon (1842) mentions grapes, persimmons, and hackberries as food of the ivorybills in addition to beetles, larvae, and large grubs. Mcllhenny, 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 Vernoll 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 duck-like 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 clarionet." 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 tattoo like other woodpeckers, such as described by Thompson (1885), and which Mcllhenny (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 tattoos 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 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 non-migratory 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 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 non-breeding seasons in areas where no nests have been located and where no one has been able to find the birds subsequently.

The family groups apparently keep together until the following nesting season, and Mr. Kuhn has reported seeing groups of from three to five birds even as late as early March. Hoyt (1905) states that "after the young leave the nest in April they and the parents remain together until the mating season in December. During the summer they are always found in bands of three to five, and I have never seen more than the latter number."

Conservation--Arthur T. Wayne (1910) records having "encountered more than two hundred of these rare birds [in Florida] during the years 1892, 1893, and 1894." Today it is doubtful if there are a fourth of that number left alive in its entire range.

A number of theories have been advanced for the increasing scarcity of the ivorybill, that most often mentioned being the destruction of its natural habitat, the virgin cypress and bottomland forests of the South. Commercialization, avarice of collectors, shooting for food by natives, predation by natural enemies that can enter its hole (but not the pileated) are likewise suggested, while Allen and Kellogg (1937) suggest that with increasing scarcity because of their sedentary habits, inbreeding and lack of sex rhythm resulting in weak young and infertile eggs have become increasingly important. At this writing the National Association of Audubon Societies has established a Fellowship at Cornell University for the study of the ivorybill, and it is hoped that the incumbent, James Tanner, may ascertain such facts regarding the bird and its habits that constructive measures for its preservation can be undertaken.
 

*Original Source: Bent, Arthur Cleveland. 1939. Smithsonian Institution United States National Museum Bulletin 174: 1 - 12. United States Government Printing Office

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