Habitat

Includes winter range -- i.e. year-round range.

USA

The most eloquent descriptions of the Ivory-billed Woodpecker's habitats are those provided by the colonial naturalists who observed the species in habitats relatively untouched by humans. For example, Alexander Wilson (Wilson and Bonaparte 1831: 132, describing habitats near Wilmington, NC), wrote that the Ivory-bill “. . . seeks the most towering trees of the forest; seemingly particularly attached to those prodigious cypress swamps, whose crowded giant sons stretch their bare and blasted or moss-hung arms midway to the skies. In these almost inaccessible recesses, amid ruinous piles of impending timber . . .”

Jim Tanner, in unpublished notes for an oral presentation to the National Association of Audubon Societies in 1939, added another dimension: “The Ivory-bill has frequently been described as a dweller in dark and gloomy swamps, has been associated with muck and murk, has been called a melancholy bird, but it is not that at all—the Ivory-bill is a dweller of the tree tops and sunshine; it lives in the sun, not the shade.”

Hasbrouck's (Hasbrouck 1891b Hasbrouck, E. M. (1891b). The present status of the Ivory-billed Woodpecker (Campephilus principalis). Auk 8:174-186. Close ) assessment of the status of the Ivory-billed placed the focus of its status in 1891 on what he referred to as the “pine line”—where pine (Pinus spp.) and baldcypress (Taxodium distichum) intergrade. Acknowledging that the Ivory-billed had once been a bird of uplands, as well as lowlands, he argued that the species was, by 1891, restricted to areas where bald-cypress could grow. His mapped limits of 1891 distribution were based on known occurrence and the limits of swamp forest essentially along a 30-m contour line.

Obvious characteristics essential in Ivory-billed habitats include: (1) very extensive, continuous forest areas, (2) very large trees, and (3) agents of tree mortality that result in a continuing supply of recently dead trees. Perhaps less obvious, but I believe essential, is an open forest through which such a large bird can fly—although when traveling long distances, the Ivory-billed often flew above the canopy.

Photos of the species and certain Ivory-billed habitat in the U.S. (Ridgway 1898b Ridgway, R. (1898b). The home of the Ivory-bill. Osprey 3:35-36. Close ; Allen Allen 1937 Allen, A. A. (1937). Hunting with a microphone the voices of vanishing birds. National Geographic Magazine 71:697-706. Close , Allen 1939b Allen, A. A. (1939b). "Ivory-billed Woodpecker." In Life histories of North American woodpeckers., edited by A. C. Bent, 1-12. U.S. Natl. Mus. Bull. 174. Close ; Allen and Kellogg 1937 Allen, A. A. and P. P. Kellogg. (1937). Recent observations on the Ivory-billed Woodpecker. Auk 54:164-184. Close ; Tanner Tanner 1941 Tanner, J. T. (1941). Three years with the Ivory-billed Woodpecker, America's rarest bird. Audubon Magazine 43 (1):5-14. Close , Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close ) and in Cuba (Dennis 1948a Dennis, J. V. (1948a). A last remnant of Ivory-billed Woodpeckers in Cuba. Auk 65:497-507. Close ) show an open canopy and often a very open forest with trees of diverse species and ages. Agents of tree mortality such as fire and flooding help maintain such openess. Several authors (e.g., Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close , Short 1982 Short, L. L. (1982). Woodpeckers of the World. Monograph Series 4, Delaware Museum of Natural History, Greenville, DE, USA. Close ) have commented that an abundance of other species of woodpeckers can be indicative of quality Ivory-billed habitat. Tanner (Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close ) censused all woodpeckers and measured the abundance of dead wood in 3 areas of the Singer Tract; he demonstrated that the abundance of woodpeckers increased as the amount of dead wood increased, suggesting that availability of woodpecker food increased with the dead wood.

Tree-species composition also seems to have been important in delimiting Ivory-billed habitats. Faster growing trees (“softwoods”) not only reach a size for Ivory-billed cavity excavation (see Breeding: nest site, below) more quickly than slower growing trees, but their wood is less hard and more easily excavated. Known cavity trees include such soft-wood species as pines, red maple (Acer rubrum), sugarberry (Celtis laevigata), and cabbage palmetto (Sabal palmetto), but also a few harder wood species such as baldcypress (Taxodium distichum). In any species, cavity excavation was in wood that was “a bit punky” (Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close : 69), rotted by fungi whose growth is facilitated by the high humidity environment of swamps.

From 1937 through 1939, Tanner, as part of his study of the Ivory-billed in Louisiana, described the bottomland forest of the Tensas River region (Tanner Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close , Tanner 1986 Tanner, J. T. (1986). Distribution of tree species in Louisiana bottomland forests. Castanea 51 (3):168-174. Close ), selecting homogeneous areas “showing no signs of disturbance by man” (Tanner 1986 Tanner, J. T. (1986). Distribution of tree species in Louisiana bottomland forests. Castanea 51 (3):168-174. Close : 168) for his habitat quantification. His analysis included a cross-section of habitats from open water to dry uplands, crossing “swamp” in which the soil was flooded most of the year, first bottoms that were very poorly to well-drained, and second bottoms that were inundated or had soil saturated with water <2% of the growing season (Tanner 1986 Tanner, J. T. (1986). Distribution of tree species in Louisiana bottomland forests. Castanea 51 (3):168-174. Close ). Tanner's categorization of “first bottoms” included a diversity of habitats with distinct differences in tree-species composition. The Singer Tract was in the “heart of the first bottoms” and there Tanner found the Ivory-billeds almost exclusively in higher parts, areas rarely inundated more than a few months of the year (Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close ). Such areas had soils that were moderately well-drained alluvial clay and were dominated by sweetgum (Liquidambar styraciflua), Nuttall's oak (Quercus nuttalli), and green ash (Fraxinus pennsylvanicus; Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close : 15). Among other species prominent in the forest were American elm (Ulmus americana), willow oak (Quercus phellos), water oak (Q. nigra), and sugarberry. Approximately 30–35% of the trees >30 cm diameter at breast height (dbh) were sweetgums, 5–12% Nuttall's oak, 10% green ash, 10–12% American elm, 8–10% hackberry (probably = sugarberry [Celtis sp.]), 5–20% water oak, 7–15% willow oak (percentages estimated from data for sites B and C in Fig. 2 of Tanner 1986 Tanner, J. T. (1986). Distribution of tree species in Louisiana bottomland forests. Castanea 51 (3):168-174. Close ). Trees of all age classes were found because of high mortality due to flooding, wind, and lightning. Tanner (Tanner 1942bb Tanner, J. T. (1942b). The Ivory-billed Woodpecker. National Audubon Society Research Report 1. National Audubon Society, New York, New York. Close ) noted that Ivory-billeds rarely entered the flats dominated by overcup oak (Quercus lyrata) and water hickory (Carya aquatica).

CUBA

Because of the extent of cutting and degradation, Lamb (Lamb 1957 Lamb, G. R. (1957). The Ivory-billed Woodpecker in Cuba. Pan-American Section, Int. Comm. Bird Preserv., Res. Rep. 1. Close ) considered it impossible to know much about what Ivory-billed habitat had been in Cuba. Like its U.S. counterpart, the Cuban Ivory-billed was a bird of vast, old-growth forests with large trees, a steady supply of recently dead trees, and probably an open canopy (Lamb 1957 Lamb, G. R. (1957). The Ivory-billed Woodpecker in Cuba. Pan-American Section, Int. Comm. Bird Preserv., Res. Rep. 1. Close , Short 1982 Short, L. L. (1982). Woodpeckers of the World. Monograph Series 4, Delaware Museum of Natural History, Greenville, DE, USA. Close , Short and Horne 1986 Short, L. L. and J. F. M. Horne. (1986). The Ivorybill still lives. Natural History 95 (7):26-28. Close , García 1987 García, F. (1987). Las aves de Cuba subspecies endémicas. Havana, Cuba: Editorial Gente Nueva. Close , JAJ). Early records suggest a similarity in habitats of U.S. and Cuban Ivory-billeds, but by the last half of the nineteenth century, the Ivory-billed in Cuba was restricted to uplands; quick-draining lateritic soils provide the conditions for development of the extensive pine uplands the species then favored (Lamb 1957 Lamb, G. R. (1957). The Ivory-billed Woodpecker in Cuba. Pan-American Section, Int. Comm. Bird Preserv., Res. Rep. 1. Close ). Lamb found the birds nesting in pines and occasionally foraging in hardwoods. In describing the vastness of the area required, García (García 1987 García, F. (1987). Las aves de Cuba subspecies endémicas. Havana, Cuba: Editorial Gente Nueva. Close ) noted that the home range of a pair of Ivory-billeds could support 30 pairs of West Indian Red-bellied Woodpeckers (Melanerpes superciliaris).