Abstract
Somewhere in the deep, remote areas of the southeast where few men have ever gone, an extremely rare and endangered bird may still exist. Probably no other bird has caused more concern or accounted for more total manhours spent than the elusive ivory-billed woodpecker, Campepbilus principalis principatis, the largest woodpecker on the North American continent. With an average length of20 inches, it is the second largest in the world, exceeded only by the imperial woodpecker, Carnpepbitus imperialis of Mexico. The plumage of the ivory-bill, as it is more commonly called, is glossy black. A white stripe begins on each cheek and continues down each side of the neck where the two stripes curve in to meet in the middle of the back. The outer half of the secondary feathers and the inner ends of the primaries are white. When the wings are folded against the body the white appears as a triangle on the lower back. The male has a red crest and the female a black one. The bill, as the name indicates, is ivory white.
The ivory-bill's call sounds like that of a toy tin horn. This call is repeated as it feeds. Its hammering is sometimes a single resonant beat, but more often it is a series of double beats (Tanner, 1942).
The nearly extinct ivory-bill formerly resided in large overmature forests of river swamps of the southern and eastern United States from southeastern Oklahoma, northeastern Arkansas, southeastern Missouri, southeastern Illinois, and southeastern North Carolina, southward to the Gulf Coast of eastern Texas, eastward to southern Florida (Tanner, 1942).
Allen and Kellogg (193 7) found ivorybills digging trenches in rotted wood. They more often scaled off bark from recently dead trees to get at the insects and larvae hidden beneath. It was found that most feeding was done in dead pines near the edges of swamps. Occasional feeding was noted on the ground. Tanner (1942) found the most common feeding behavior is to knock the bark off recently dead trees with a sidewise blow Or a quick flick of the bill. They also chisel into the tree making somewhat conical holes. They most often feed in areas with large sized dead or dying trees that contain an abundance of wood boring beetles. With a maximum range of up to 6 square miles of suitable habitat per pair, some have appeared to wander considerable distances, probably due to the availability of food.
Studies in the past have shown their diet to consist of both animal and plant matter (Bendire, 1894; Cottam and Knappen, 1939; Tanner, 1942; Wilson, 1811). Cottam and Knappen (1939) found in 3 ivory-billed woodpecker stomach analyses the following: 46 % of the combined content was of animal origin and 54 % was of vegetable origin. A majority of the animal matter eaten is long horned beetles, Cerarnbicidae, though a small amount of other beetles were found. Some of the vegetable matter eaten is as follows: seeds of both magnolia and poison ivy and berries from both Tupelo and Black Gum.
Nest holes were located between extremes of 25 to 70 feet above the ground. Tanner (1942) stated that most nest holes in the Singer Tract near Tallulah, Louisiana were located above grounds that were at least partly covered by water during the nesting season. Both male and female work together on digging out the nest (Audubon, 1831). Nest hole openings described by several other writers and Tanner (1942) are described as being oval or irregular. The nest hole opening averages 5.4 inches tall by 4.3 inches wide. The nest cavity has an average depth of 20.6 inches and an inside diameter of 9. 5 inches from side to side by 6.8 inches from front to back (Tanner, 1942).
The breeding season runs from late winter to early spring. Anywhere from 1 to 5 eggs are laid between January and May. Early nests had fewer eggs and young than did later nests. Schmaus (1938) stated that the egg clutches of some bird species may vary with the abundance of food and there may have been a seasonal increase in the food supply of the ivory-billed woodpecker in April and May that resulted in the birds laying more eggs then. The male does the majority of the brooding while both the male and the female share the responsibility of feeding the young. No ivory-bill nest has ever been observed through the entire incubation period. Therefore, no exact length of the period is known. Tanner (1942) gives a probable average of 20 days. The young stay in the nest approximately 5. weeks. When the young birds are out of the nest they accompany the parents on feeding trips for another 2 months. During this time they are fed by the parents. After approximately 2 to 3 months they become independent (Tanner, 1942).
The most important reason for the species' decline was the cutting back and lumbering of overmature forests which contain dead and dying trees that house the wood boring beetle larvae that form the staple of their diet. In the past, illegal shooting may have been a factor. The ivory-billed woodpeckers began to disappear when the loggers invaded the southern swamps. During 1885 to 1900, the logging industries' greatest growth period, the largest decline of the bird's numbers occurred.
The first serious study of the ivorybilled woodpecker was conducted by a team from Cornell University headed by Ors. Arthur A. Allen and P. Paul Kellogg in 1935. Continuous observations of the nesting birds were done at that time. Allen and Kellogg's pictures and recordings are still the standard today. On that team was a young Carnell graduate student named James T. Tanner. Tanner was later chosen by the National Audubon Society to conduct a complete study. He worked on this project for 3 years, earning his doctorate in 1939 and writing the book, The Ivory-billed Woodpecker, published in 1942. This monograph remains the definitive work today.