Life histories of North American woodpeckers

by Arthur Cleveland Bent

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.