Wood Stork

Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.

Bent Life History for the Wood Stork – the common name and sub-species reflect the nomenclature in use at the time the description was written.

A striking and a picturesque bird is the wood ibis, also known in Florida as “gannet” or “flinthead,” both appropriate names. It is a permanent resident in the hot, moist bottom lands of our southern borders and seldom straggles far north of our southern tier of States. To see it at its best one must penetrate the swampy bayous of Louisiana or Texas, where the big water oaks and tupelos are draped in long festoons of Spanish moss, or the big cypress swamps of Florida, where these stately trees tower for a hundred feet or more straight upward until their interlacing tops form a thick canopy of leaves above the dim cathedral aisles. One must work his way through almost impenetrable thickets of button willows, underbrush, and interlacing tangles of vines. He must wade waist deep or more in muddy pools, where big alligators lurk unseen or leave their trails on muddy banks, as warnings to be cautious, or where the deadly moccassin may squirm away under foot or may lie in wait, coiled up on some fallen log, ready to strike. If not deterred by these drawbacks, or by the clouds of malarial mosquitos or by the hot, reeking atmosphere of the tropical swamps, he may catch a fleeting glimpse of the big white birds or hear their croaking notes as they fly from the tree tops above. Probably he may see a solitary old “flint heady’ perched in the top of some old dead tree in the distance, standing on one leg, with his head drawn in upon his shoulders and his great bill resting on his chest. Perhaps there may be a whole flock of them in such a tree; but the observer will not get very near them, for the wood ibis is an exceedingly shy bird, and a sentinel is always on the lookout. One is more likely to see the wood ibis on the wing, flying in flocks to or from its feeding grounds, or circling high in the air above its breeding rookery. On the wing it shows up to the best advantage, sailing gracefully on motionless wings, a big white bird, with black flight feathers in its long wings and in its short tail.

Nesting: My experience with the nesting habits of the wood ibis has been rather limited. In the big Jane Green cypress swamp, near the upper St. Johns River in Florida, we found a breeding colony in April, 1902. The cypresses here were the largest I have ever seen, measuring 6 feet or more in diameter at the base, tapering rapidly to about 3 feet in diameter, and then running straight up at about that size for 75 or 100 feet to the first limb. The nests were placed in the tops of the tallest cypresses and far out on the horizontal limbs; they were practically inaccessible by any means at our disposal, so we had to be content with seeing or hearing the birds fly off.

Near Cape Sable we were more fortunate, as the absence of cypress swamps in this region compelled the wood ibises to nest in smaller trees. We found a small colony of them breeding on an island in Bear Lake, about 2 miles back from the coast. The birds were very shy, leaving the island when we were about 100 yards away, and not coming within gunshot afterwards. There were about 20 nests in the tops of the red mangroves, from 12 to 15 feet from the ground; they were large nests, about 3 feet in diameter, made of large sticks, very much like the nests of the larger herons, and were completely covered with excrement. All the nests held young birds inï various stages of growth.

Willard Eliot (1892) describes a typical nesting colony of wood ibises, found in southern Florida on March 23, as follows:

Out in the center of the lake was a small island about 100 feet in diameter, with about 3 feet elevation above the water. There were several large cypress trees besides a thick undergrowth of bay trees. What a sight met our gaze from the shore, the trees on the island were white with the jbises standing close to. gether on the limbs, besides a number of American egrets, Florida cormorants, and anhingas. The ibises were nesting and we could see a number of the birds sitting on their nests. Most of the nests were on the island, but we found two trees near the shore, one had five nests and the other seven. After looking over the field I proceeded to climb the first tree, a large cypress, the nests were placed 50 feet from the ground and were saddled flatly on the top of a horizontal limb. One limb had four nests in a row and were so close together that their edges touched. A typical nest was 18 inches across by 5 inches deep outside, only slightly depressed inside, made of coarse sticks lined with moss and green bay leaves. The eggs were chalky white and nearly always blood stained; the average set is three but we found sets of two and four.

In the spring of 1913 F. lvI. Phelps (1914) visited a large rookery of wood ibises in the Big Cypress Swamp of Lee County, Florida, in which he estimated that there were not less than 5,000 pairs of these birds. He says:

Mr. Baynard, who visited this rookery in February, 1912, before the cypress trees had leaved out, gave it as his opinion that there were not less than seven or ï eight thousand nests of the wood ibis here. Tree after tree bore from 12 to 20 or more nest~s of this species, and in one I counted 32. Years ago before the egrets and spoonbills had become so sadly decimated, for they once bred here in large numbers, it must have been a spectacle so imposing as to defy an adequate description. The egrets, wood ibis, and spoonbills all nest high up in the cypress trees, very few under 50 feet and many 75 and 80 feet up. At this season, the middle of March, nearly all the nests contained young. A few of the wood ibis and egrets were still incubating eggs, but these were more than likely birds that had been broken up elsewhere.

Frederic H. Kennard has sent me some notes on a rookery fully as large, if not larger, which he explored in Okaloacoochee Slough in southern Florida. It was in some enormous cypress trees, 4, 5, 6, 7, and even 9 feet in diameter, grown well apart, so that most of them had good, spreading tops. It had been for years the place where the Seminoles came for their dugouts, as it contained the biggest and finest cypresses in the land. The rookery was perhaps from 100 to 200 yards across, and he followed it for about half a mile or more. Not all the trees were occupied, but most of the good ones held 4 or 5 to 20 nests apiece, clear way up on the tops of the trees. It was almost impossible to make any estimate of their number, even approximately, without spending a couple of days counting their nests, but there must have been several thousand flying about, or perched solemnly on the tops of the trees.

His guide, Tom Hand, estimated that there were 10,000 nests, for from a tree he climbed he could see the nests extending along the edge for a mile. At the other end of the rookery they all appeared to be building their nests. There was an almost steady stream of birds, perhaps 25 at a time, all flying to some live willows, breaking off twigs and flying back to the rookery with them. An old bird would fly up to the willows and alight, perhaps grasping several twigs in his feet, in order to get a firmer hold; he would then saw, pull, and yank at some twig with his bill; if unsuccessful, he would try another twig until, at last, he could break one off and fly away with it. In the rookery they frequently saw the birds flying overhead with long twigs or small branches, with the leaves still on them, or with long streamers of moss for nest linings.

Among the many courtesies extended to me by Oscar E. Baynard was an excellent opportunity to make an intimate acquaintance with a nesting colony of wood ibises; it was not as large as the one described above, but the nests were fairly accessible and the birds were rather tamer than usual. In the northern part of Polk County, Florida, lies a large tract of wilderness, unsettled and with no roads worthy of the name; it is largely flat pine woods with numerous large and small cypress ponds or swamps scattered through it. Here on March 7, 1925, after a 30-mile drive over some of the toughest trails I have ever driven, through woods, bogs, and cypress swamps, we camped near the edge of a long cypress swamp and visited the rookery in it the next day. We estimated that the colony consisted of between 200 and 300 pairs of wood ibises; no other species was nesting with them. We had not waded more than 75 or 100 yards into the swamp, where the water averaged about knee deep, when we began to see the ibises in the tree tops or on their nests. The cypress trees were of fair size, 12 to 18 inches in diameter, heavily festooned with Spanish moss, and the nests were mostly between 50 and 60 feet above us. The birds were not shy at first and we had no difficulty in approaching near enough to photograph groups of them perched on the nesting trees or on other tall dead trees in the vicinity. When we began climbing the trees they became more wary, but they perched on the tops of more distant trees and frequently flew over us. Some of the trees held only two or three nests, but most of them held from half a dozen to a dozen. The nests were in or near the tops of the trees, mostly well out on the horizontal branches and often beyond our reach. They were surprisingly small and flimsy structures, not much larger than well made night heron’s nests, ill adapted, it seemed to me, to the needs of such large, heavy birds. The foundations of the nests were loosely made of rather large, dead sticks, on which more substantial nests were built of finer twigs and fresh, budding leaf stems of the cypress; some were also partially lined with green leaves of bay, oak, or maple. Perhaps the nests would be added to, as incubation advances, as is customary with some of the herons. Most of the nests contained three eggs, some only two, and at least two nests held four eggs. All of of the eggs that we collected were fresh.

Eggs: The wood ibis lays usually three, sometimes four, eggs and very rarely five. The shape varies from ovate to elliptical ovate or even elongate ovate. The shell is smooth, but finely granulated or finely pitted. The color is dull or dirty white or cream white, without any markings, except occasional blood stains.

The measurements of 40 eggs average 67.9 by 46 millimeters; the eggs showing the four extremes measure 73 by 46.2, 64.7 by 54.9, 60.8 by 46.8 and 70.9 by 34.3 millimeters.

Young: George M. Sutton (1924) gives the following interesting account of his visit to a colony of wood ibises, in which the young birds were about ready to fly:

As evening came I noticed that from the hammock far to the westward issued forth strange sounds the like of which I had never heard. I accredited them to alligators and bullfrogs, thinking at the time that Florida ‘gators and frogs probably could, and perhaps usually did set up such a disturbance. Although it was so far away, the penetrating quality of the racket made us believe that the sound would be very great close at hand. It was so far distant that we heard but an incessant mumbling, varied occasionally with higher shriller, tones.

Although I constantly noticed wood ibises issuing in small flocks from this hammock, or returning to it, I never seemed to connect the strange sound with the birds; it hardly seemed credible that birds should make such a noise. But when we visited the ‘Gator Lake hammock on March 20, we found that the strange noises of the days before had come from a large “Flint-head” colony. As we approached, the racket increased steadily, and soon we could detect individual grunts, loud and deep-throated; shrill squeals, incessant and angry; bellowing, coughing, deep wheezing, bleating: all in the most unbelievably hurried, earnest fashion, as though their fervor had to be kept at white heat all evening long. Even now we could not really see the birds, save those few which occasionally flew out to investigate us, or to search a feeding ground for the evening. But it was strangely exciting to listen, and to picture in our minds what might be going on in that dense hammock to the accompaniment of the weird notes we were hearing As we drew near, masses of the birds took wing and drifted about, soaring quite low for a time and gradually mounting higher and higher. Not until we had come very close did we realize that a large proportion of the colony was young birds, fully fledged but standing about on somewhat uncertain legs and very hesitant to fly. They were droll creatures. They seemed aware of our presence all the time hut never turned their heads our way, seeming to prefer to listen intently and jump off with much flapping and squaking at what they considered the psychological moment. Many of them where standing on their large, flat, whitewashed nests; but I believe they had long since forgotten their own cradles and were standing about regardless of family relationships. Occasionally one very near us would lose his balance, and, hanging by his neck and toes, after much hideous noise and commotion would finally regain his perch or flap away. On the heads of the full-fledged young the juvenal feathering was still apparent. Many of them stood about with open mouths: whether bellowing or not.

Plumages: The downy young wood ibis is partially covered with short, thick, wooly, white down; the front half of the head and the spaces between the feather tracts are bare. I have never seen any small juvenals, but Audubon (1840) says:

The young are dusky-grey all over, the quills and tail brownish-black. The headall covered with down, excepting just at the base of the hlll. After the first molt, the bare space extends over the head and cheeks; the downy feathers of the hind head and neck are dusky; the general color of the plumage is white, the quills and tail nearly as in the adult, hut with less gloss.

In the first winter plumage, which is worn without much change until the first postnuptial molt, the posterior half of the head and the whole neck is thinly covered with coarse, hairlike feathers, mixed dusky, brown and whitish, darkest and longest on the occiput. The body plumage is dull white. Some of the scapulars and tertials are extensively tipped with dull brown and the rectrices and remiges are brownish black with dull greenish reflections. Most of the immature birds that I have seen, taken from October to May fall into this class, hence I think that the fully adult plumage must be assumed at the first postnuptial molt in September and October, when the young bird is 15 or 16 months old. However, the young bird is not yet fully adult for some feathering still remains on the neck. The scaly, bare head and neck of the old “flint head” are probably not acquired for at least another year. Audubon (1840) says:

The wood ibis takes four years in attaining full maturity, although birds of the second year are now and then found breeding. This is rare, however, for the young birds live in flocks by themselves, until they have attained the age of about 3 years. They are at first of a dingy brown, each feather edged with paler; the head is covered to the mandibles with short downy feathers, which gradually fall off as the bird advances in age. In the third year, the head is quite bare, as well as a portion of the upper part of the neck. In the fourth year, the bird is as you see it in the plate. The male is much larger and heavier than the female, but there is no difference in color between the sexes.

The complete molt of the adult apparently occurs in September and October; I have seen no evidence of a molt in the spring or of any seasonal difference in plumage.

Food: The wood ibis is mainly a fresh water bird and prefers to feed in shallow, muddy ponds, marshes and slouglis; but it also resorts occasionally, perhaps often to salt-water mud flats and shoals. I frequently saw them in winter, usually from two to four birds, feeding on the extensive mud flats of Boca Ceiga Bay in company with American egrets, little blue, Louisiana, and Ward herons. They must fly long distances to feed, for this locality, in Pinellas County, Florida, is at least 100 miles from the nearest known rookery. Two birds were seen occasionally in a little pond hole on Long Key beside a much frequented road, where they fed with the egrets, totally unconcerned with many passing automobiles. I once sat and watched them feeding within 20 yards of my blind and was much impressed by the loud clattering of their bills, as they walked about with long, deliberate steps, feeling for their food and scooping it out of the mud and water. A method of feeding, that I have never seen or read about, is described in some notes sent to me by Mr. Kennard, based on observations made by his guide. He reported watching a number of them at close range. They were in some open water with a very muddy bottom, walking back and forth, dragging their bills beside them, pointed downward and backward, opening and shutting them repeatedly, as if sifting the mud through them, after the manner of flamingos. He says that on moonlight nights numbers of them may be seen feeding in the sloughs; and on a cloudy, rainy day they could be seen all over the prairie, feeding, perhaps on grasshoppers.

Audubon’s (1840) account of the feeding habits of the wood ibis is worth quoting, as follows:

This species feeds entirely on fish and aquatic reptiles, of which it destroys an enormous quantity, in fact more than it teats; for if they have been killing fish for half an hour and have gorged themselves, they suffer the rest to lie on the water untouched, when it becomes food for alligators, crows, and vultures, whenever these animals can lay hold of it. To procure its food, the wood ibis walks through shallow muddy lakes or bayous in numbers. As soon as they have discovered a place abounding in fish, they dance as it were all through it, until the water becomes thick with the mud stirred from the bottom by their feet. The fishes, on rising to the surface, are instantly struck by the beaks of the ibises, and, on being deprived of life, they turn over and so remain. In the course of 10 or 15 minutes, hundreds of fishes, frogs, young alligators, and water snakes cover the surface, and the birds greedily swallow them until they are completely gorged, after which they walk to the nearest margins, place themselves in long rows, with their breasts all turned toward the sun, in the manner of pelicans and vultures, and thus remain for an hour or so. Besides the great quantity of fishes that these ibises destroy, they also devour frogs, young alligators, wood rats, young rails and grakies, fiddlers and other crabs, as well as snakes and small turtles. They never eat the eggs of the alligator, as has been alleged, although they probably would do so, could they demolish the matted nests of that animal, a task beyond the power of any bird known to me. I never saw one eat anything which either it or some of its fellows had not kllled. Nor will it eat an animal that has been dead for sometime, even although it may have been killed by it&.lf. When eating, the clacking of their mandibles may be heard at the distance of several hundred yards.

Grinnell, Bryant and Storer (1918) record the stomach contents of three wood ibises taken in Imperial County, California; one contained 3 tadpoles, 4 water beetles, 2 paddle bugs, and some moss and slime; another, 9 tadpoles, a water beetle, 9 dragon fly larvae, and a carp; and the third held 10 carp, a catfish, 2 bony tails (fish) and a water cricket. Another bird from the same region examined by Dr. Harold C. Bryant (1919) had in its stomach 10 seeds of the screw bean, 2 seeds of mesquite, parts of 4 water beetles and some finely comminuted vegetable material.

Behavior: In flight the wood ibises are splendid birds and one never tires of watching them, as they fly along in flocks, high over the tree tops flapping their long wings or scaling at intervals, all in perfect unison. Even more interesting are the spectacular aerial evolutions in which these birds so often indulge. Rising in a flock, they soar in wide circles, mounting higher and higher, crossing and recrossing in a maze of spirals, until they are almost beyond vision in the ethereal blue. Then suddenly they dash downward and repeat the operation or else drift away on motionless wings until lost to sight. They are easily recognized at a great distance, great white birds with jet black flight feathers, with long necks and heavy bills and with long legs extended far beyond their short black tails.

Distance lends enchantment to this species; the sign of the cross, so boldly written in black and white on the distant sky, one stands and admires; but not so with the awkward, ungainly fowl that we see perched on a tree in a hunched-backed attitude of uncouth indolence. Its behavior on the ground is well described by Doctor Coues (1874) as follows:

The carriage of the wood ibis is firm and sedate, almost stately; each leg is slowly lifted and planted with deliberate precision, before the other is moved, when the birds walk unsuspicious of danger. I never saw one run rapidly, since on all the occasions when I have been the cause of alarm, the bird took wing directly. It springs powerfully from the ground, bending low to gather strength, and for a little distance flaps hurriedly with dangling legs, as if it was much exertion to lift so heavy a body.

Wood ibises are among the wariest of birds. Even on their breeding grounds it is usually difficult to approach them; when they first rise from their nests they may circle once around the intruder and then they disappear and do not return. When feeding or when perched on a tree resting and dozing there is always a sentinel on the watch; even when roosting at night they are difficult to approach; the crackling of a twig, the rustling of underbrush, the slighest sound or the glimpse of a man, which their keen ears or eyes can detect, will put them on the alert; it is then useless to attempt a closer approach; they are off and will not return.

The only note I have ever heard from an adult wood ibis is a hoarse croak, usually uttered when disturbed or frightened. it is generally a silent species. Young birds are very noisy, however.

Enemies: The wood ibis has not suffered much from the hand of man; it is so wary that it is not easily approached and is generally well able to take care of itself; its plumage has never been much in demand, for it is not an attractive bird at close quarters; and it has never been considered a game bird, as its flesh is tough and unpalatable. It has few natural enemies and so it is likely to survive for a long time in its native wilderness.

Willard Elliot (1892) writes.:

A great pest of all rookery birds is the crow, and if an ibis leaves the nest for an instant down comes the black dare-devil with a scream of delight and grabs an egg by sticking his bill into it and flying away. The ibis seems to be very much afraid of them and I have seen a crow almost take an egg out from under one of them and they would croak and draw back their bills as if to strike, but never did.

Audubon (1840) says:

One of the most curious circumstances connected with this species is, that although ~he birds are, when feeding, almost constantly within the reach of large alligators, of which they devour the young, these reptiles never attack them; whereas, if a duck or a heron comes within the reach of their tails, it is immediately killed and swallowed. The wood ibis will wade up to its belly in the water, around the edgcs of “alligators’ holes,” without ever being injured; but should one of these birds be shot, an alligator immediately makes toward it and pulls it under water. The garfish is not so courteous, but gives chase to the ibises whenever an opportunity occurs. The snapping-turtle is also a great enemy to the young birds of this species.

Dr. Henry Bryant (1861), on a visit to a rookery in Florida, found the alligators very aggressive; he writes:

The moment the boat which I had had hauled there was launched, the alligatoes assembled for the purpose of examining the now visitor; and before we had arrived at the breeding place there were more than .50 following the boat, the nearest almost within reach of the oars. On shooting a bird, the instant it touched the water it was seized by an alligator; and I was obliged to kill half a dozen of these creatures before I could secure a specimen, and even after this I was generally obliged to fire one barrel at the bird and the other at the nearest alligator.

DISTRIBUTION
Breeding range: Southeastern United States, Central and South America south to Patagonia. East to South Carolina (Colleton County); Florida (Amelia Island, St. Johns River, St. Augustine, Orlando, Lake Kissimmee, Lake Okeechohee and Cape Sable); Cuba; British Guiana (Georgetown); Brazil (Monte Negro, Para, and Iguage). South to Brazil (Rio Grande do Sud); Uruguay (Rio Negro, and Sta. Elena); Argentina (Concepcion, Barracas al Sud and Cordoba). West to Argentina (Tucuman); Peru (Upper Ucayali River and Tumbez); Ecuador (Babahoyo, probably); Costa Rica (La Palma and Rio Frio); Nicaragua (Escondido River, probably); Guatemala (Coban); Mexico (southeastern Yucatan, Cozumel Island, Tepic, Mazatlan, and the Gulf of California). North to northwestern Mexico (Gulf of California); Texas (Corpus Christi); Louisiana (Cameron and Bayou Sara); and Mississippi (Rodney).

Postbreeding summer range: After the breeding season there is generally in the United States, a distinct northward movement of both adults and immatures. At this time the species may be locally common in southern California (San Diego, Saticoy, San Bernardino Valley, Oceanside, Dagget, Bixby, Claremont, Dominguez, and Los Angeles); Arizona (Santa Cruz River, Yuma, Needles, Temple, and the valleys of the Colorado, Gila, San Pedro, and Bill Wi]liams Rivers); northern Texas (Gainesville); New Mexico (Fort Fillmore and Fort Thorn); southern Illinois (across from St. Louis, Mo.); and southeastern Indiana (Lyons, Bicknell, near Brookville, and Terre Haute).

Winter range: In winter the wood ibis withdraws only a short distance from the extremes of its breeding range. It is occasionally found wintering as far north as Royal Palm Hammock, Florida (Hurter, 1881) and Mount Pleasant, South Carolina (Wayne, 1910).

Spring migration: Early dates of arrival: Florida, Orlando, March 5, Indian River, March 28, Smyrna, March 29; Mississippi, Bioxi, March 21; Texas, Corpus Christi, March 25.

Fall migration: Late dates of departure: Florida, Amelia Island, November 2, Indian Key Reservation, October 1; Mississippi, Rodney, September 25.

Casual records: Stragglers have wandered much farther than the regular postbreeding summer range and have been taken or noted north to Montana (southwestern part of the State, June 18, 1911); Wyoming (Yellowstone, Grand Canyon, July 16, 1925); Colorado (two near Denver, August 30, 1902); Wisconsin (Racine, September 10, 1868; another at La Crosse and a third on Rock River between Janesville and Edgerton); Michigan (Monroe, June 19, 1910); Massachusetts (Georgetown, June 19 1880, Chilmark, Martha’s Vineyard, November 26, 1918; and Seekonk, July 17, 1896); Vermont (Burlington); and Ontario (Sincoe, November, 1892).

Egg dates: Florida: 54 records, December 8 to April 30; 27 records, January 10 to March 21.