Ivory-billed woodpeckers once ranged throughout the southeastern United States, from southern Florida and the Gulf Coast, north to North Carolina and southern Illinois, and west to southeastern Oklahoma and eastern Texas. They were also widespread on the main island of Cuba. Extensive logging of their primary forest habitat greatly reduced their range in both North America and Cuba. They were presumed extinct for a number of years before being rediscovered and videotaped in eastern Arkansas in April of 2004. Currently the Cache River National Wildlife Refuge, in Monroe County, Arkansas is the only place where ivory-billed woodpeckers are known with any certainty to persist. The last confirmed sighting of an ivory-billed woodpecker in Cuba was in 1987.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
- Jackson, J. 2002. "Ivory-billed Woodpecker (Campephilus principalis)" (On-line). The Birds of North America Online. Accessed May 09, 2005 at http://bna.birds.cornell.edu/BNA/account/Ivory-billed_Woodpecker/.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Resident formerly from eastern Texas, southeastern Oklahoma, northeastern Arkansas, southeastern Missouri, southern Illinois, southern Indiana, Kentucky, and southeastern North Carolina south to the Gulf Coast and southern Florida, and throughout Cuba. The last positive sightings in Cuba (1987) were in a small tract of degraded habitat (Collar et al. 1992); intensive surveys in Cuba in 1991 and 1993 found no evidence of any remaining individuals. A sighting in southeastern Louisiana in 1999 has not been confirmed. At least one bird was reported in eastern Arkansas in 2005, but that record is controversial. Prior to that, the last confirmed sighting in the United States was in the mid-1940s in northern Louisiana. Putative sightings of this species in the Florida Panhandle in 2005 and 2006 still lack adequate confirmation an extant population there.
U.S.A. (southcentral and southeastern), Cuba
Ivory-billed woodpeckers are the largest woodpeckers in the United States. They measure 48 to 53 cm long, weigh 450 to 570 g, and have wingspans of about 78 cm. Males tend to be slightly larger than females. Ivory-billed woodpeckers have glossy black plumage that contrasts sharply with the white stripes that run from the base of each wing to the sides of the head. The inner primary and secondary wing feathers are also white, and these feathers form a white shield on the back when the wings are folded. Female ivory-billed woodpeckers have a black crests on their heads, males have bright red crests. The irises are a pale lemon-yellow color and the nostrils are covered by tufts of white feathers that keep out debris when the birds are chiseling. The legs and feet are gray, and the toes are long, each bearing a sharp, curved, black claw. Ivory-billed woodpeckers get their name from their distinctive white, chisel-shaped, 7.6 centimeter-long bills, which function as multi-purpose tools for obtaining food, excavating nest cavities, and communicating with conspecifics.
Range mass: 450 to 570 g.
Range length: 48 to 53 cm.
Average wingspan: 78 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently
Length: 50 cm
Weight: 511 grams
Habitat and Ecology
Ivory-billed woodpeckers require expansive areas of continuous forest with large trees, and they must have a constant supply of dead or dying trees in which they can excavate cavities and forage for beetle larvae, their staple food. For this reason, they frequent areas of recent disturbance by fire, flood, or hurricane. These large birds prefer forests with relatively open canopies in which they can fly unhindered. Given these requirements, they nest in a diverse array of tree species, including pines, bald cypress, cabbage palmetto, sugarberry, and red maple.
Ivory-billed woodpeckers once inhabited both the upland and lowland forests of the southeastern U.S. However, as the upland pine forests were logged in the 19th century, the birds' habitat shrunk to only include bald cypress swamps and bottomland forests of sweetgum, Nuttall's oak, willow oak, water oak, sugarberry, green ash, and American elm. The Big Woods area of Arkansas is one such bottomland forest.
In Cuba, ivory-billed woodpeckers once occupied both pine and hardwood forests. By the 1950's, they were restricted to a small region in the east characterized by logged pine forest interrupted by occasional hardwood stands along streams. In this area they nested primarily in large dead pines.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest
- Lamb, G. 1958. Excerpts from a report on the ivory-billed woodpecker (Campephilus principalis bairdii) in Cuba. Bulletin of the International Committee for Bird Preservation, 7: 139-144.
Comments: In U.S.: swampy forests, especially large bottomland river swamps of coastal plain and Mississippi Delta and cypress swamps of Florida, in areas with many dead and dying trees. Cuba: mainly in high country in pine forests, also pine-hardwood forest and hardwood forest; formerly also in lowland forest.
Nested in tall old trees (various species in U.S., mainly old and dying pines in Cuba), at height of about 8-21 m.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Nomadic in some areas.
Ivory-billed woodpeckers feed on large beetle larvae, which they find by stripping away the bark of dead or dying trees. Occasionally, they forage for insects on the ground in recently burned areas or in fallen logs. Insects consumed belong to the families Cerambycidae, Buprestidae, Elateridae, Scolytidae, Melasidae, and also include arboreal termites (Isoptera). However, insects only make up about half the diet; in addition, ivory-billed woodpeckers eat berries, nuts and seeds, including cherries, southern magnolia fruits and seeds, pecan nuts, hickory nuts, poison ivy seeds, grapes, persimmons, hackberries, and possibly acorns.
Animal Foods: insects
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: omnivore
Comments: Ate mainly larvae and adults of wood-boring beetles that live between bark and wood of dying and newly dead trees. Sometimes dug tenches in rotten wood to obtain beetles. Also ate some fruits/seeds of trees.
Thanks to their chisel-like bills, ivory-billed woodpeckers are potential ecosystem engineers. The tree cavities they excavate are probably used by an array of other species once the woodpeckers leave. These species might include wood ducks, eastern bluebirds, opossums, gray squirrels, and honeybees.
Because they share many similarities, some have suggested that ivory-billed woodpeckers compete with pileated woodpeckers for food and prime cavity sites. Competition between the two species may have intensified after forests were logged, with pileated woodpeckers, which adapt much more readily to human disturbance, being more successful. However, interactions between ivory-billed woodpeckers and other woodpecker species have never been directly studied.
Ivory-billed woodpeckers are predators of insects, but it is doubtful they have a huge impact on insect populations as their numbers are so low. Because they eat fruits and seeds, it is possible that ivory-billed woodpeckers disperse seeds.
Recently, researchers discovered a new species of feather mite on museum skins of ivory-billed woodpeckers. They named the new mite Pterotrogus principalis. This mite is the only known parasite of ivory-billed woodpeckers.
- Pterotrogus principalis
- Mironov, S., J. Dabert, R. Ehrnsberger. 2005. A new species of the feather mite genus Pterotrogus Gaud (Analgoidea: Pteronyssidae) from the ivory-billed woodpecker Campephilus principalis L. (Aves: Piciformes). Annals of the Entomological Society of America, 98(1): 13-17.
No one has ever recorded predation on ivory-billed woodpeckers, except for that by humans. Potential predators include raccoons, rat snakes, great horned owls, barred owls, Cuban crows, American crows, red-shouldered hawks, Cooper's hawks, and Stygian owls. There is a report of a pair of ivory-billed woodpeckers chasing a Cooper's hawk away from their nest while scolding it, and another report of a female ivory-billed woodpecker giving a warning call and flying closer to her fledgling when a red-shouldered hawk appeared in the area. There are also reports of ivory-billed woodpeckers rapidly switching to the other side of trees when birds of prey materialized nearby.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 0 - 5
Comments: One or two known possibly extant occurrences. The last known population in Cuba apparently went extinct between 1987 and 1991 (Lammertink, 1995, Cotinga, Vol. 3).
Zero to 50 individuals
Comments: Population size is very small or nonexistent.
Population density was estimated at 1 pair per 16-43 sq km (formerly, USFWS 1980, Collar et al. 1992). Reported to be either sedentary or nomadic in different areas.
Life History and Behavior
Communication and Perception
Ivory-billed woodpeckers, like most birds, perceive their environment through visual, auditory, tactile, and chemical means. The relative acuteness of ivory-billed woodpeckers' senses is unknown, but presumably they have good vision and hearing as they use auditory and visual signals to communicate with one another. They have a distinctive call note, "kent", which is often described as sounding similar to a note from a tin trumpet or a New Year's Eve party horn. When pairs are together they utter somewhat softer call notes, and when more than two are together they engage in soft chatter or sometimes a chorus of long, upslurred notes. Family members trade call notes back and forth throughout the day as they forage, growing quiet towards evening. Ivory-billed woodpeckers also communicate by drumming their heavy bills on tree surfaces. Their distinctive drum sound is a double rap, the first rap slightly louder than the second, so that it sounds like the second is an echo of the first. Finally, the bright red crest of a male ivory-billed woodpecker sends a clear visual signal, and no doubt serves a communicatory function, but its exact purpose has not been studied.
Communication Channels: visual ; acoustic
The lifespan of ivory-billed woodpeckers is unknown. Some speculate that they could live 20 years or more.
- Cornell Lab of Ornithology, 2005. "Rediscovering the ivory-billed woodpecker" (On-line). Accessed May 11, 2005 at http://birds.cornell.edu/ivory/.
Ivory-billed woodpeckers are presumed to be monogamous. No information is available on the occurrence of extra-pair copulations or extra-pair fertilizations in this species.
Mating System: monogamous
Because of the rarity of ivory-billed woodpeckers, little data is available on their reproduction. Limited data suggests that ivory-billed woodpeckers begin building nests in late January, lay eggs in February, and that the young fledge in April. Given this timespan, it is likely that these birds follow the same general pattern followed by other North American woodpeckers: nest cavity building takes about 2 weeks, egg laying takes 2 to 5 days, and incubation takes about 2 weeks. Clutch sizes of 1 to 6 eggs have been reported, with an average of 2.7. The young are known to leave the nest about 5 weeks after hatching, and they have an unusually long period of association with their parents that may last a year or more after fledging, although they can forage on their own at three months old. Ivory-billed woodpeckers seem to breed only once per year. Their age at sexual maturity is unknown.
Breeding interval: Ivory-billed woodpeckers breed once yearly.
Breeding season: Breeding is likely to occur between January and April.
Average time to hatching: 2 weeks.
Average fledging age: 5 weeks.
Average time to independence: 1 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Ivory-billed woodpeckers begin preparing for the arrival of their offspring at least two weeks before the first egg is laid. They select a dead or partially dead tree with wood that is soft enough for excavation but not so soft that it would provide easy access for predators. They then begin to excavate a cavity, usually just below an overhanging branch or stub (which may keep out rain and/or provide shade). There are conflicting reports on who does the excavating: some say that the male and female take turns and some say that the female does all the work herself. The resulting entrance hole is oblong in shape, about 11 cm wide and 14 cm tall. The cavity itself is about 25 cm wide at its widest point and measures about 54 cm from roof to floor. After the eggs have been laid, the male ivory-billed woodpecker roosts in the a cavity at night with the eggs, and later with the young. During the day the adults take turns brooding their altricial young. Feeding duties are shared more or less equally between males and females. Both feeding and brooding are most intense for the first few days after the eggs hatch and then gradually decline as the nestlings grow older; for example, 30 feedings per day drops to about 15 feedings per day later in the nesting period. Ivory-billed woodpeckers keep their nests fairly clean, but only males have been observed doing the cleaning, removing fecal material and dropping it away from the nest. Parents continue to feed their young for more than two months after the young fledge and the young may stay with their parents for over a year even though they are capable of feeding themselves at three months.
Parental Investment: altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female); post-independence association with parents
- Jackson, J. 2002. "Ivory-billed Woodpecker (Campephilus principalis)" (On-line). The Birds of North America Online. Accessed May 09, 2005 at http://bna.birds.cornell.edu/BNA/account/Ivory-billed_Woodpecker/.
Cuba: nesting season was March-June, peak in April. Clutch size usually was 2-3. Incubation lasted about 20 days, by both sexes. Young were tended by both parents, left nest at about 5 weeks, fed by adults for additional 2 months or more.
Date Listed: 03/11/1967
Lead Region: Southeast Region (Region 4)
Where Listed: Entire
Population location: Entire
Listing status: E
For most current information and documents related to the conservation status and management of Campephilus principalis , see its USFWS Species Profile
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2009Critically Endangered
- 2008Critically Endangered
- 2005Critically Endangered
- 2004Critically Endangered
- 2000Critically Endangered
United States: Ivory-billed woodpecker populations have been in decline since the early 19th century, and perhaps even earlier. Their requirement for vast tracts of undisturbed forest made them vulnerable to intense logging efforts in their native range. By the 1930's it was estimated that fewer than 25 ivory-billed woodpeckers remained in the United States. A substantial fraction of those were living in the 81,000-acre Singer Tract of northeastern Louisiana. Though efforts were made to preserve this valuable bit of remaining habitat, which was the largest remaining piece of virgin forest in the southern United States, the Singer Tract was logged by the late 1940s and with it went much hope for the continued existence of ivory-billed woodpeckers. However, unconfirmed sightings were occasionally noted throughout the years from Missouri, Florida, Georgia, South Carolina, Texas, and Louisiana. Reports of their existence in Florida prompted the formation of the Chipola River Wildlife Sanctuary in 1950, but there were no further sightings and the sanctuary was discontinued two years later. In 2002, after a reported ivory-bill sighting in the area, researchers conducted a two month long search in the Pearl River Swamp of Louisiana, but found no conclusive evidence of their persistence in this area. Finally, in February of 2004, a kayaker saw an ivory-billed woodpecker in the Cache River National Wildlife refuge in Monroe County, Arkansas. This sighting was confirmed when researchers were able to videotape the bird in April of 2004, the first confirmed ivory-billed woodpecker sighting since 1944. After gathering additional evidence for a year, including sound recordings, the researchers published their findings in April 2005. The federal government has pledged $10 million towards the protection of ivory-billed woodpeckers, and another $10 million has been pledged by private sector groups and individuals. A recovery plan that will protect the birds' critical habitat is currently in the works. In the meantime, managers of the wildlife refuge have restricted access to 5,000 acres of forest in the area where ivory-billed woodpeckers were spotted.
Cuba: Ivory-billed woodpecker populations declined sharply in the late 19th century, when acres of old-growth forest were cleared to make way for sugar plantations. Later harvesting of forests for timber exacerbated the decline. By the 1950s, ivory-billed woodpeckers were restricted to a remote area in the eastern part of the country, in what was then the Oriente Province (now Santiago de Cuba). Management plans were adopted that involved educating the public about the birds' plight and setting aside preserves protected by wardens. Ivory-billed woodpeckers managed to persist in eastern Cuba until at least 1987. However, the last unconfirmed sighting occurred in northeastern Cuba in 1991, and ivory-billed woodpeckers are now presumed extirpated in Cuba.
The IUCN currently lists ivory-billed woodpeckers as critically endangered, after having listing them as threatened in 1988, extinct in 1994, and critically endangered in 2000. The U.S. Fish and Wildlife Service lists them as endangered.
US Migratory Bird Act: no special status
US Federal List: endangered
CITES: no special status
IUCN Red List of Threatened Species: critically endangered
- BirdLife International, 2004. "Campephilus principalis" (On-line). 2004 IUCN Red List of Threatened Species. Accessed May 09, 2005 at www.redlist.org.
- Fitzpatrick, J., M. Lammertink, M. Luneau Jr., T. Gallagher, B. Harrison, G. Sparling, K. Rosenberg, R. Rohrbaugh, E. Swarthout, P. Wrege, S. Swarthout, M. Dantzker, R. Charif, T. Barksdale, J. Remsen Jr., S. Simon, D. Zollner. Published online April 28, 2005. Ivory-billed woodpecker (Campephilus principalis) persists in continental North America. Science, 10.1126/science.1114103 (Science Express). Accessed May 09, 2005 at http://www.sciencemag.org/cgi/rapidpdf/1114103v1.pdf.
- Garrido, O. 1985. Cuban endangered birds. Pp. 992-999 in P Buckley, M Foster, E Morton, R Ridgely, F Buckley, eds. Neotropical Ornithology, Vol. Ecological Monographs, no. 36. Washington, D.C.: The American Ornithologists' Union.
- U.S. Department of the Interior, , U.S. Fish and Wildlife Service, U. S. Department of Agriculture. 2005. "Once-thought extinct ivory-billed woodpecker rediscovered in Arkansas" (On-line). U. S. Fish and Wildlife Service. Accessed May 11, 2005 at http://www.fws.gov/southeast/news/2005/r05-029.html.
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G1 - Critically Imperiled
Reasons: Formerly occurred in the southeastern United States and Cuba; declined to extinction or near extinction due primarily to habitat loss from logging; recent records from Arkansas and Florida are in need of confirmation.
Global Long Term Trend: Decline of >90%
Comments: Decline was primarily the result of loss of habitat via logging; one of the last known inhabited areas in the United States (Tensas River, Louisiana) was cleared for soybean production; overhunting also may have contributed to the decline.
After the reported rediscovery in February 2004, intensive surveys involving dozens of observers, automatic cameras and recording equipment have been carried out in the Big Woods area3. Searches have also continued in other parts of the south-east USA that have historic records of the species, with specific searches taking place in 21 locations across that area in 2006-200714. An endangered species recovery team of c.50 members has been appointed12, and a recovery plan has been drawn up. By early 2010, the US Fish and Wildlife Service (USFWS) had spent $14 million on efforts to document and protect the species, which have been burdened by the investigation of dubious records and hoaxes22. In October 2009, the search for the species in the USA was suspended owing to funding constraints22. Early in 2010, the USFWS was on the verge of approving a final recovery plan22. Part of the Big Woods area falls within the Cache River and White River National Wildlife Refuges. In Cuba there have been a number of searches for the species, and further searches were planned for 2010 and 201120. Conservation Actions Proposed
Carry out further surveys in the south-east USA (particularly near recent reported sightings) to try to locate further individuals, document their continued existence and determine the population size and distribution. Ensure strict protection of any nests and nesting trees, if found. Continue to carry out searches for the species in Cuba, where c. 80% of suitable habitat has not been explored. Ensure the implementation of appropriate protective measures if a population is found in Cuba. Engage birdwatchers in the search for the woodpecker and raise awareness about the importance of reporting and documenting any sightings16. Use GIS to remotely identify suitable search sites where the species may occur16.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
The only known negative impact of ivory-billed woodpeckers on humans results from their protected status: 5,000 acres of land surrounding the locality where ivory-billed woodpeckers were rediscovered have been closed to hunting and fishing, and locals fear that more will follow. Currently, hunting and fishing drive the local economy. However, it is likely that the economic benefits of tourism resulting from visitors to the area in search of ivory-billed woodpeckers will more than make up for this potential loss.
Economic Importance for Humans: Positive
Ivory-billed woodpeckers have had economic importance to humans for centuries. Native Americans collected them for their bills, which symbolized successful warfare. American colonists traded with Native Americans for the bills, which they saw as a curiosity. Later, the heads of ivory-billed woodpeckers were sold as souvenirs and the bills were marketed as real ivory. In the late 19th century, collecting natural items became popular, and ornithologists paid dearly--$40 to $50 per bird--to add ivory-billed woodpeckers to their collections. In Cuba, humans sometimes ate ivory-billed woodpeckers or killed them for sport. Of course, the economic importance of ivory-billed woodpeckers waned as their numbers dwindled, but now once again they are having an impact. The rediscovery of ivory-billed woodpeckers has received much popular press, and ornithologists and birdwatchers are already flocking to Arkansas in the hopes of glimpsing the rare bird. The Cache River National Wildlife Refuge happens to be situated in one of the poorest areas of the nation, but locals are hoping that the rediscovery of ivory-billed woodpeckers will give their economy a jump start. No doubt there will at least be a demand for lodging to accomodate the influx of ecotourists, and the surrounding towns may actually see the opening of new businesses, after experiencing a steady population decline stretching back to the 1950s.
Positive Impacts: food ; body parts are source of valuable material; ecotourism
- Associated Press, 2005. "Poor towns hope to feather nests" (On-line). Accessed May 10, 2005 at http://www.cnn.com/2005/TRAVEL/05/05/woodpecker.ap/index.html.
The Ivory-billed Woodpecker (Campephilus principalis) is one of the largest woodpeckers in the world, at roughly 20 inches in length and 30 inches in wingspan. It was native to the virgin forests of the southeastern United States (along with a separate subspecies native to Cuba). Due to habitat destruction, and to a lesser extent hunting, its numbers have dwindled to the point where it is uncertain whether any remain, though there have been reports that it has been seen again. Almost no forests today can maintain an Ivory-billed Woodpecker population.
The species is listed as critically endangered and possibly extinct by the International Union for Conservation of Nature (IUCN). The American Birding Association (ABA) lists the Ivory-billed Woodpecker as a Class 6 species, a category the ABA defines as "definitely or probably extinct."
Reports of at least one male Ivory-billed Woodpecker in Arkansas in 2004 were investigated and subsequently published in April 2005 by a team led by the Cornell Lab of Ornithology (Fitzpatrick et al., 2005). No definitive confirmation of those reports emerged, despite intensive searching over five years following the initial sightings.
A $10,000 reward was offered in June 2006 for information leading to the discovery of an Ivory-billed Woodpecker nest, roost or feeding site. In December 2008, the Nature Conservancy announced a reward of $50,000 to the person who can lead a project biologist to a living Ivory-billed Woodpecker.
In late September 2006, a team of ornithologists from Auburn University and the University of Windsor published reports of their own sightings of Ivory-billed Woodpeckers along the Choctawhatchee River in northwest Florida, beginning in 2005 (Hill et al., 2006). These reports were accompanied by evidence that the authors themselves considered suggestive for the existence of Ivory-billed Woodpeckers. Searches in this area of Florida through 2009 failed to produce definitive confirmation.
Despite these high-profile reports from Arkansas and Florida and sporadic reports elsewhere in the historic range of the species since the 1940s, there is no conclusive evidence for the continued existence of the Ivory-billed Woodpecker; i.e., there are no unambiguous photographs, videos, specimens or DNA samples from feathers or feces of the Ivory-billed. Land acquisition and habitat restoration efforts have been initiated in certain areas where there is a relatively high probability that the species may have survived to protect any possible surviving individuals.
- 1 Taxonomy
- 2 Description
- 3 Habitat and diet
- 4 Breeding biology
- 5 Status
- 6 Publicity and tourism
- 7 References
- 8 External links
The Ivory-billed is the type species for the genus Campephilus, a group of large American woodpeckers. Although the Ivory-billed looks very similar to the Pileated Woodpeckers they are not close relatives as the latter is a member of the genus Dryocopus.
Ornithologists have traditionally recognized two subspecies of this bird: the American Ivory-billed, the more famous of the two, and the Cuban Ivory-billed Woodpecker. The two look similar despite differences in size and plumage. There is some controversy over whether the Cuban Ivory-billed Woodpecker is more appropriately recognized as a separate species. A recent study compared DNA samples taken from specimens of both Ivory-billed birds along with the Imperial Woodpecker, a larger but otherwise very similar bird. It concluded not only that the Cuban and American Ivory-billed woodpeckers are genetically distinct, but also that they and the Imperial form a North American clade within Campephilus that appeared in the Mid-Pleistocene. The study does not attempt to define a lineage linking the three birds, though it does imply that the Cuban bird is more closely related to the Imperial.
The American Ornithologists' Union Committee on Classification and Nomenclature has said it is not yet ready to list the American and Cuban as separate species. Lovette, a member of the committee, said that more testing is needed to support that change, but concluded that "These results will likely initiate an interesting debate on how we should classify these birds." Before this study, it was thought that the Cuban Ivory-billed were descended from mainland woodpeckers, either introduced to Cuba by Native Americans or accidentals that flew to the island themselves.
While recent evidence suggesting that American Ivory-billed Woodpeckers may still exist in the wild has caused excitement in the Ornithology community, no similar evidence exists for the Cuban Ivory-billed bird, believed to be extinct since the last sighting in the late 1980s.
The Ivory-billed Woodpecker ranks among the largest woodpeckers in the world and is the largest in the United States. The closely related and likewise possibly extinct Imperial Woodpecker (C. imperialis) of western Mexico is, or was, the largest woodpecker. The Ivory-billed has a total length of 48 to 53 cm (19 to 21 in) and, based on very scant information, weighs about 450 to 570 g (0.99 to 1.26 lb). It has a typical 76 cm (30 in) wingspan. Standard measurements attained included a wing chord length of 23.5–26.5 cm (9.3–10.4 in), a tail length of 14–17 cm (5.5–6.7 in), a bill length of 5.8–7.3 cm (2.3–2.9 in) and a tarsus length of 4–4.6 cm (1.6–1.8 in).
The bird is shiny blue-black with white markings on its neck and back and extensive white on the trailing edge of both the upper- and underwing. The underwing is also white along its forward edge, resulting in a black line running along the middle of the underwing, expanding to more extensive black at the wingtip. In adults, the bill is ivory in color, chalky white in juveniles. Ivory-bills have a prominent crest, although in juveniles it is ragged. The crest is black in juveniles and females. In males, the crest is black along its forward edge, changing abruptly to red on the side and rear. The chin of an ivory-bill is black. When perched with the wings folded, ivory-bills of both sexes present a large patch of white on the lower back, roughly triangular in shape. These characteristics distinguish it from the smaller and darker-billed Pileated Woodpecker. The Pileated normally is brownish-black, smoky, or slaty black in color. It also has a white neck stripe but the back is normally black. Pileated juveniles and adults have a red crest and a white chin. Pileateds normally have no white on the trailing edges of their wings and when perched normally show only a small patch of white on each side of the body near the edge of the wing. However, Pileated Woodpeckers, apparently aberrant individuals, have been reported with white trailing edges on the wings, forming a white triangular patch on the lower back when perched. Like all woodpeckers, the ivory-bill has a strong and straight bill and a long, mobile, hard-tipped, barbed tongue. Among North American woodpeckers, the ivory-bill is unique in having a bill whose tip is quite flattened laterally, shaped much like a beveled wood chisel.
The bird's drum is a single or double rap. Four fairly distinct calls are reported in the literature and two were recorded in the 1930s. The most common, a kent or hant, sounds like a toy trumpet often repeated in series. When the bird is disturbed, the pitch of the kent note rises, it is repeated more frequently, and is often doubled. A conversational call, also recorded, is given between individuals at the nest, and has been described as kent-kent-kent. A recording of the bird, made by Arthur A. Allen, can be found here.
The Ivory-billed Woodpecker is sometimes referred to as the Grail Bird, the Lord God Bird, or the Good God Bird, all based on the exclamations of awed onlookers. Other nicknames for the bird are King of the Woodpeckers and Elvis in Feathers.
Habitat and diet
Ivory-billeds are known to prefer thick hardwood swamps and pine forests, with large amounts of dead and decaying trees. Prior to the American Civil War, much of the Southern United States was covered in vast tracts of primeval hardwood forests that were suitable as habitat for the bird. At that time, the Ivory-billed Woodpecker ranged from east Texas to North Carolina, and from southern Illinois to Florida and Cuba. After the Civil War, the timber industry deforested millions of acres in the South, leaving only sparse isolated tracts of suitable habitat.
The Ivory-billed Woodpecker feeds mainly on the larvae of wood-boring beetles, but also eats seeds, fruit, and other insects. The bird uses its enormous white bill to hammer, wedge, and peel the bark off dead trees to find the insects. These birds need about 25 km2 (9.7 sq mi) per pair so they can find enough food to feed their young and themselves. Hence they occur at low densities even in healthy populations. The more common Pileated Woodpecker may compete for food with this species.
The Ivory-billed Woodpecker is thought to pair for life. Pairs are also known to travel together. These paired birds will mate every year between January and May. Both parents work together to excavate a nest in a dead or partially dead tree about 8–15m from the ground before they have their young. Nest openings are typically ovular to rectangular in shape, and measure about 12–14 cm tall by 10 cm wide (4"-5 3/4" by 4")
Usually two to five eggs are laid and incubated for 3 to 5 weeks. Parents incubate the eggs cooperatively, with the male incubating from approximately 4:30 PM–6:30 AM while the female foraged, and vice-versa from 6:30 AM–4:30 PM. They feed the chicks for months. Young learn to fly about seven to eight weeks after hatching. The parents will continue feeding them for another two months. The family will eventually split up in late fall or early winter.
Ornithologists speculate that they may live as long as 30 years.
Heavy logging activity exacerbated by hunting by collectors devastated the population of Ivory-billed Woodpeckers in the late 19th century. It was generally considered extinct in the 1920s when a pair turned up in Florida, only to be shot for specimens.
In 1932, a Louisiana state representative, Mason Spencer of Tallulah, disproved premature reports of the demise of the species when, armed with a gun and a hunting permit, he killed an Ivory-billed Woodpecker along the Tensas River and took the specimen to his state wild life office in Baton Rouge.
By 1938, an estimated twenty woodpeckers remained in the wild, some six to eight of which were located in the old-growth forest called the Singer Tract, owned by the Singer Sewing Company in Madison Parish in northeastern Louisiana, where logging rights were held by the Chicago Mill and Lumber Company. The company brushed aside pleas from four Southern governors and the National Audubon Society that the tract be publicly purchased and set aside as a reserve. By 1944, the last known Ivory-billed Woodpecker, a female, was gone from the cut-over tract.
Reported sightings: 1940s to 1990s
The only footage of the Ivory-billed Woodpecker was recorded in 1935 along with the sound of its call. The Ivory-billed Woodpecker was listed as an endangered species on 11 March 1967, though the only evidence of its existence at the time was a possible recording of its call made in East Texas. The last reported sighting of the Cuban subspecies (C. p. bairdii), after a long interval, was in 1987; it has not been seen since. The Cuban Exile journalist and author John O'Donnell-Rosales, who was born in the area of Cuba with the last confirmed sightings, reported sightings near the Alabama coastal delta in 1994, but these were never properly[clarification needed] investigated by state wildlife officials.
Two tantalizing photos were given to Louisiana State University museum director George Lowery in 1971 by a source who wished to remain anonymous but who came forward in 2005 as outdoorsman Fielding Lewis.
The photos, taken with a cheap Instamatic camera, show what appears to be a male Ivory-billed perched on the trunks of two different trees in the Atchafalaya Basin of Louisiana. The bird's distinctive bill is not visible in either photo and the photos – taken from a distance – are very grainy. Lowery presented the photos at the 1971 annual meeting of the American Ornithologists Union. Skeptics dismissed the photos as frauds; seeing that the bird is in roughly the same position in both photos, they suggested they may have been of a mounted specimen.
There were numerous unconfirmed reports of the bird, but many ornithologists believed the species had been wiped out completely, and it was assessed as "extinct" by the International Union for Conservation of Nature and Natural Resources in 1994. This assessment was later altered to "critically endangered" on the grounds that the species could still be extant.
2002 Pearl River expedition
In 1999, there was an unconfirmed sighting of a pair of birds in the Pearl River region of southeast Louisiana by a forestry student, David Kulivan, which some experts considered very compelling. In a 2002 expedition in the forests, swamps, and bayous of the Pearl River Wildlife Management Area by LSU, biologists spent 30 days searching for the bird.
In the afternoon of 27 January 2002, after ten days, a rapping sound similar to the "double knock" made by the Ivory-billed Woodpecker was heard and recorded. The exact source of the sound was not found because of the swampy terrain, but signs of active woodpeckers were found (i.e., scaled bark and large tree cavities). The expedition was inconclusive, however, as it was determined that the recorded sounds were likely gunshot echoes rather than the distinctive double rap of the Ivory-billed Woodpecker.
2004/2005 Arkansas reports
A group of seventeen authors headed by the Cornell Lab of Ornithology (CLO) reported the discovery of at least one Ivory-billed Woodpecker, a male, in the Big Woods area of Arkansas in 2004 and 2005, publishing the report in the journal Science on 28 April 2005 (Fitzpatrick et al., 2005).
One of the authors, who was kayaking in the Cache River National Wildlife Refuge, Monroe County, Arkansas, on 11 February 2004, reported on a website the sighting of an unusually large red-crested woodpecker. This report led to more intensive searches in the area and in the White River National Wildlife Refuge, undertaken in secrecy for fear of a stampede of bird-watchers, by experienced observers over the next fourteen months. About fifteen sightings occurred during the period (seven of which were considered compelling enough to mention in the scientific article), possibly all of the same bird. One of these more reliable sightings was on 27 February 2004. Bobby Harrison of Huntsville, Alabama and Tim Gallagher of Ithaca, New York, both reported seeing an ivory-billed woodpecker at the same time. The secrecy of the search permitted The Nature Conservancy and Cornell University to quietly buy up Ivory-billed habitat to add to the 120,000 acres (490 km2) of the Big Woods protected by the Conservancy.
A large woodpecker was videotaped on 25 April 2004; its size, wing pattern at rest and in flight, and white plumage on its back between the wings were cited as evidence that the woodpecker sighted was an Ivory-billed Woodpecker. That same video included an earlier image of what was suggested to be such a bird perching on a Water Tupelo (Nyssa aquatica).
The report also notes that drumming consistent with that of Ivory-billed Woodpecker had been heard in the region. It describes the potential for a thinly distributed population in the area, though no birds have been located away from the primary site.
In the fall of 2006, researchers developed and installed an "autonomous observatory" using robotic video cameras with image processing software that detects and records high resolution video of birds in flight inside a high probability zone in the Cache River area. As of August 2007, hundreds of birds have been recorded, including Pileated Woodpeckers, but not the Ivory-billed Woodpecker.
We were very skeptical of the first published reports, and ... data were not sufficient to support this startling conclusion.
The paper was not published. Questions about the evidence for Ivory-billed Woodpecker persisted. The CLO authors could not say with absolute certainty that the sounds recorded in Arkansas were made by Ivory-bills. Some skeptics, including Richard Prum, believe the video could have been of a Pileated Woodpecker.
An article by Dina Cappiello in the Houston Chronicle published 18 December 2005 presented Richard Prum's position as follows:
Prum, intrigued by some of the recordings taken in Arkansas' Big Woods, said the evidence thus far is refutable.
The American Birding Association largely stayed out of the debate. On page 13 of Winging It (November/December 2005), a brief reference was made:
The ABA Checklist Committee has not changed the status of the Ivory-billed Woodpecker from Code 6 (EXTINCT) to another level that would reflect a small surviving population. The Committee is waiting for unequivocal proof that the species still exists.
Prum, Robbins, Brett Benz, and I remain steadfast in our belief that the bird in the Luneau video is a normal Pileated Woodpecker. Others have independently come to the same conclusion, and publication of independent analyses may be forthcoming [...] For scientists to label sight reports and questionable photographs as 'proof' of such an extraordinary record is delving into 'faith-based' ornithology and doing a disservice to science."
Fitzpatrick and co-authors responded with a lengthy piece in the same scientific journal, protesting Jackson's harsh language, dismissive tone, "factual errors," and "poorly substantiated opinions" about the original paper. One of the most rancorous debates in the history of ornithology had begun in earnest. The two sides each published additional responses that seemed, to many ornithological observers, to have departed markedly from accepted scientific decorum. Jackson accused the Fitzpatrick team of "untruths", and Fitzpatrick accused Jackson of obviating the normal peer-review system with an opinion piece "treated as a scientific contribution by the public media."
In March 2006, a team headed by David A. Sibley of Concord, MA published a response in the journal Science, asserting that the videotape was most likely of a Pileated Woodpecker, with mistakes having been made in the interpretation of its posture. They conclude that it lacked certain features of an Ivory-billed Woodpecker, and had others consistent with the Pileated; they asserted positively that the blurry video images belonged to Pileated Woodpecker. The CLO team responded in the same issue of Science, standing by their original findings, stating:
Claims that the bird in the Luneau video is a normal pileated woodpecker are based on misrepresentations of a pileated's underwing pattern, interpretation of video artifacts as plumage pattern, and inaccurate models of takeoff and flight behavior. These claims are contradicted by experimental data and fail to explain evidence in the Luneau video of white dorsal plumage, distinctive flight behavior, and a perched woodpecker with white upper parts." (Fitzpatrick et al., 2006a)
In sum, no evidence confirms the alleged rediscovery of the Ivory-billed Woodpecker. Indeed, confidence in the claim has eroded with failure to verify its existence despite massive searches.
A 2007 paper concluded that the Luneau video was consistent with the Pileated Woodpecker:
New video analysis of Pileated Woodpeckers in escape flights comparable to that of the putative Ivory-billed Woodpecker filmed in Arkansas shows that Pileated Woodpeckers can display a wingbeat frequency equivalent to that of the Arkansas bird during escape flight. The critical frames from the Arkansas video that were used to identify the bird as an Ivory-billed Woodpecker are shown to be equally, or more, compatible with the Pileated Woodpecker.…The identification of the bird filmed in Arkansas in April 2004 as an Ivory-billed Woodpecker is best regarded as unsafe. The similarities between the Arkansas bird and known Pileated Woodpeckers suggest that it was most likely a Pileated Woodpecker.
All ARU double raps suggesting the presence of an Ivory-billed Woodpecker should be reconsidered in light of the phenomenon of duck wingtip collisions, especially those recorded in the winter months, when duck flocks are common across flooded bottomlands of the southeastern United States.
Cornell search efforts 2005–09
Cornell-organized searches in Arkansas and elsewhere from 2005 to 2008 did not produce any new photographic evidence of the species. The press release summarizing the 2005–6 search season stated:
There were teasing glimpses and tantalizing sounds, but the 2005–2006 search for the Ivory-billed Woodpecker in Arkansas has concluded without the definitive visual documentation being sought. The search, led by the Cornell Lab of Ornithology, with support from Audubon Arkansas, stretched from November through April when ivory-bill activity would be highest and a lack of leaf-cover permitted clear views through the dense forest.… “The search teams were very skilled, not only technically but in the execution of the search,” said Dr. John Fitzpatrick, director of the Cornell Lab of Ornithology. “Even though we didn’t get additional definitive evidence of the ivory-bill in Arkansas, we’re not discouraged. The vastness of the forest combined with the highly mobile nature of the bird warrant additional searching.”
It is interesting to note that, despite his harsh criticism of the 2005 evidence, Jerome A. Jackson agrees with the value of additional searches. In May 2006, it was announced that a large search effort led by the Cornell team had been suspended for the season with only a handful of unconfirmed, fleeting sightings to report. At that point, conservation officers allowed the public back into areas of the Cache River National Wildlife Refuge that had been restricted upon the initial reported sightings. The 2006–07 search season had similar results to those of the previous year: 
The Lab and its partners concluded the 2006–07 field season in Arkansas at the end of April with no additional definitive evidence of ivory-bills to complement the data gathered in 2004 and 2005. But [Ronald] Rohrbaugh and others are convinced the research should continue, not only in Arkansas, but in other states that are part of the bird’s historic range. “We’ll return to Arkansas for at least another field season,” says Rohrbaugh. “Searches there and searches conducted by other agencies throughout the Southeast are still turning up reports of sounds that cannot be explained away. However, there’s no way to know for sure yet if reported double knocks and kent-like sounds were made by an ivory-bill or something else.”
Likewise, the 2007-08 search season did not deliver conclusive evidence of the bird:
The search teams covered lots of ground and tried new survey techniques…. Searchers documented more possible sightings and possible ivory-bill double knocks heard, but the definitive photograph, like the bird itself, remained elusive.
Cornell University did not field a search team in Arkansas during 2008–2009, but focused on mangrove habitats in southwest Florida, with a later visit planned for South Carolina. According to a Cornell University press release from January 2009, the 2008–09 season will be the last Cornell-sponsored search, absent confirmation of the bird:
There will be a distinctly different flavor to this season’s search for the Ivory-billed Woodpecker. Seven members of the Cornell Lab of Ornithology’s mobile search team will plunge into some of the most forbidding wilderness in southwestern Florida. …The work begins in Florida in early January and continues through mid-March. …In mid-March the Cornell Lab of Ornithology team will join the South Carolina search along the Congaree, PeeDee, and Santee Rivers.
“The U.S. Fish and Wildlife Service-funded Ivory-billed Woodpecker searches will continue through the 2008-09 search season,” says Laurie Fenwood, Ivory-billed Woodpecker Recovery Team Coordinator for the U.S, Fish and Wildlife Service.…If no birds are confirmed, the Cornell Lab of Ornithology will not send an organized team into the field next year. “We remain committed to our original goal of striving to locate breeding pairs,” says Cornell Lab of Ornithology director John Fitzpatrick. “We will continue to accept and investigate credible reports of Ivory-billed Woodpeckers, and to promote protection and restoration of the old growth conditions upon which this magnificent species depended across the entire southeastern United States.”
The 2008–09 search effort in southwest Florida found no evidence of the bird:
We have found no signs of Ivory-billed Woodpeckers. No sightings, double knocks or calls, no replies to our many double-knock imitations. We have seen a few cavities of the appropriate size and shape for ivory-bills, but these can be old, or exceptionally large Pileated Woodpecker cavities, or mammal-enlarged Pileated Woodpecker cavities.… Given the results, it is unlikely a population of any meaningful size of Ivory-billed Woodpeckers exists in south Florida.
In October 2009, Cornell scientists announced that their search for the Ivory-billed Woodpecker in North America was being suspended. As of February 2010, the Cornell researchers concluded there was no hope of saving the bird, if it still exists:
But after five years of fruitless searching, hopes of saving the species have faded. "We don't believe a recoverable population of ivory-billed woodpeckers exists," says Ron Rohrbaugh, a conservation biologist at Cornell University in Ithaca, New York, who headed the original search team.
2005/2006 Florida reports
In September 2006, new claims that the Ivory-billed Woodpecker may not be extinct were released by a research group consisting of members from Auburn University in Alabama and the University of Windsor in Ontario. Dr. Geoffrey E. Hill of Auburn University and Dr. Daniel Mennill of the University of Windsor have revealed a collection of evidence that the birds may still exist in the cypress swamps of the Florida panhandle. Their evidence includes 14 sightings of the birds and 300 recordings of sounds that can be attributed to the Ivory-billed Woodpecker, but also includes tell-tale foraging signs and appropriately sized tree nest cavities (Hill et al., 2006). This evidence remains inconclusive as it excludes the photographic or DNA evidence that many experts cite as necessary before the presence of the species can be confirmed. While Dr. Hill and Dr. Mennill are themselves convinced of the bird's existence in Florida, they are quick to acknowledge that they have not yet conclusively proven the species' existence. The research team is currently undertaking a more complete survey of the Choctawhatchee River, in hopes of obtaining photographic evidence of the bird's existence. In March 2007 the Florida Ornithological Society Records Committee voted unanimously not to accept the 2005-06 reports of the Ivory-billed Woodpecker on the Choctawhatchee River:
RC 06-610. Ivory-billed Woodpecker, Campephilus principalis. 21 May 2005 – 26 April 2006. Choctawhatchee River, Washington/Bay/Walton cos. A population of unknown size has been reported by a team from Auburn University from the lower Choctawhatchee River. There have been a few sightings but no photographs, some interesting recordings of “kent” calls and of double rap drums, and photographs taken of cavities and bark scaling. These observations were made on the heels of the much-publicized “rediscovery” of the species in Arkansas (Fitzpatrick et al. 2005). The species had not been documented to occur since 1944. The video documentation of the bird(s) from Arkansas, however, has been debated by many, although the record was accepted by the Arkansas Bird Records Committee. Our Committee felt that given the controversy of the Arkansas evidence, the species is best considered still extinct. Therefore only evidence that undoubtedly showed a living bird would be considered sufficient to accept a report.
The last specimen taken in Florida was in 1925; there have been numerous sight reports of varying credibility since, and one record of a feather found in a nest cavity in 1968 that was identified as an Ivory-billed Woodpecker inner secondary by Alexander Wetmore.
VOTE: NOT ACCEPT (0-7)
The Auburn/University of Windsor team continued search efforts but planned to cease updates on their web site in August 2009:
(12 June 2008) We completed our 2008 effort to get definitive evidence for ivorybills in the Choctawhatchee River Basin in early May…. Team members had no sightings of ivorybills and only two sound detections in 2008.… So where does all this leave us? Pretty much in the same position as in June 2006. We have a large body of evidence that Ivory-billed Woodpeckers persist along the Choctawhatchee River in the Florida panhandle, but we do not have definitive proof that they exist. Either the excitement of the ivorybill hunt causes competent birders to see and hear things that do not exist and leads competent sound analysts to misidentify hundreds of recorded sounds, or the few ivorybills in the Choctawhatchee River Basin are among the most elusive birds on the planet.
(9 February 2009) There has been little to report, and my students and I [Geoff Hill] have been enjoying the calm. We continue to work to get definitive documentation of the Ivory-billed Woodpecker in the Choctawhatchee River Basin.… To my knowledge, there have been no sightings of Ivory-billed Woodpeckers in the Choctawhatchee region since last spring. There were a few double knock detections in January, but not by my paid crew, Brian [Rolek], or me.
(2 August 2009) I haven’t posted many updates on this site in the past 9 months because there hasn’t not [sic] been much to report.… Since the winter of 2008, we have had few sightings or sound detections by anyone—none by Brian or me—and none that I would rate very highly.… In short, our experience over the past year indicates that ivorybills have moved out of the areas where we encountered them from 2005 to 2008.… There is no way to know whether the birds are in different areas in the Choctawhatchee Basin, different forests in the region, or dead.…I won’t post any more updates on this site.
Publicity and tourism
In economically struggling east Arkansas, the speculation of a possible return of the Ivory-bill has served as a great source of economic exploitation, with tourist spending up 30%, primarily in and around the city of Brinkley, Arkansas. A woodpecker "festival", a woodpecker hairstyle (a sort of mohawk with red, white, and black dye), and an "Ivory-bill Burger" have been featured locally. The lack of confirmed proof of the bird's existence, and the extremely small chance of actually seeing the bird even if it does exist (especially since the exact locations of the reported sightings are still guarded), have prevented the explosion in tourism some locals had anticipated.
Brinkley hosted "The Call of the Ivory-billed Woodpecker Celebration" in February 2006. The celebration included exhibits, birding tours, educational presentations, a vendor market, and more.
Interviews with residents of Brinkley, Arkansas, heard on National Public Radio following the reported rediscovery were shared with musician Sufjan Stevens, who used the material to write a song titled "The Lord God Bird".
Arkansas has made license plates featuring a graphic of an Ivory-billed Woodpecker.
- Audubon, John James LaForest (1835–38): The Ivory-billed Woodpecker. In: Birds of America 4. ISBN 0-8109-2061-1 (H. N. Abrams 1979 edition — the book itself is in the public domain)
- Bevier, Louis (2007): Ivory-billed debate
- Farrand, John & Bull, John, The Audubon Society Field Guide to North American Birds, Eastern Region, National Audubon Society (1977)
- Fitzpatrick, John W.; Lammertink, Martjan; Luneau, M. David Jr.; Gallagher, Tim W.; Harrison, Bobby R.; Sparling, Gene M.; Rosenberg, Kenneth V.; Rohrbaugh, Ronald W.; Swarthout, Elliott C. H.; Wrege, Peter H.; Swarthout, Sara Barker; Dantzker, Marc S.; Charif, Russell A.; Barksdale, Timothy R.; Remsen, J. V. Jr; Simon, Scott D. & Zollner, Douglas (2005): Ivory-billed woodpecker (Campephilus principalis) persists in continental North America. Science 308(5727): 1460-1462. doi:10.1126/science.1114103 PMID 15860589 preprint PDF fulltext Supporting Online Material
- Fitzpatrick, John W.; Lammertink, Martjan; Luneau, M. David Jr.; Gallagher, Tim W. & Rosenberg, Kenneth V. (2006a): Response to comment on "Ivory-billed Woodpecker (Campephilus principalis) persists in continental North America". Science 311: 1555. doi:10.1126/science.1123581 PDF fulltext Supporting Online Material Erratum (requires user account)
- Fitzpatrick, John W.; Lammertink, Martjan; Luneau, M. David Jr.; Gallagher, Tim W.; Harrison, Bobby R.; Sparling, Gene M.; Rosenberg, Kenneth V.; Rohrbaugh, Ronald W.; Swarthout, Elliott C. H.; Wrege, Peter H.; Swarthout, Sara Barker; Dantzker, Marc S.; Charif, Russell A.; Barksdale, Timothy R.; Remsen, J. V. Jr; Simon, Scott D. & Zollner, Douglas (2006b): Clarifications about current research on the status of Ivory-billed Woodpecker (Campephilus principalis) in Arkansas. Auk 123(2): 587–593. DOI: 10.1642/0004-8038(2006)123[587:CACROT]2.0.CO;2 PDF fulltext
- Fitzpatrick, John W.; Lammertink, Martjan; Luneau, M. David Jr.; Rosenberg, Kenneth V.; Gallagher, Tim W. & Rohrbaugh, Ronald W. (2006c): Response to letter by J. A. Jackson. Auk 123(4): 1189. DOI: 10.1642/0004-8038(2006)123[1189:RTLBJA]2.0.CO;2
- Gallagher, Tim W. (2005): The Grail Bird: Hot on the Trail of the Ivory-Billed Woodpecker Houghton Mifflin, Boston. ISBN 0-618-45693-7
- Hill, Geoffrey E.; Mennill, Daniel J.; Rolek, Brian W.; Hicks, Tyler L. & Swiston, Kyle A. (2006): Evidence Suggesting that Ivory-billed Woodpeckers (Campephilus principalis) Exist in Florida. Avian Conservation and Ecology - Écologie et conservation des oiseaux 1(3): 2. HTML fulltext PDF fulltext with links to appendices Erratum
- Hoose, Phillip M. (2004): The Race to Save the Lord God Bird. Farrar, Straus, and Giroux, New York. ISBN 0-374-36173-8 (children's book) HTML excerpt
- Jackson, Jerome A. (2004): In Search of the Ivory-Billed Woodpecker. Smithsonian Institution Press. ISBN 1-58834-132-1
- Jackson, Jerome A. (2006a): Ivory-billed Woodpecker (Campephilus principalis): hope, and the interfaces of science, conservation, and politics. Auk 123: 1-15. DOI: 10.1642/0004-8038(2006)123[0001:IWCPHA]2.0.CO;2 PDF fulltext
- Jackson, Jerome A. (2006b): The public perception of science and reported confirmation of the Ivory-billed Woodpecker in Arkansas. Auk 123(4): 1185–1189. DOI: 10.1642/0004-8038(2006)123[1185:TPPOSA]2.0.CO;2
- Mattsson, B. J., R. S. Mordecai, M. J. Conroy, J. T. Peterson, R. J. Cooper, and H. Christensen. Evaluating the small population paradigm for rare large-bodied woodpeckers, with implications for the Ivory-billed Woodpecker. Avian Conservation and Ecology, 2008; 3 (2): 5
- National Audubon Society (2010): Watchlist entry for the Ivory-billed Woodpecker- Retrieved 2010-FEB-1.
- Sibley, David Allen; Bevier, Louis R.; Patten, Michael A. & Elphick, Chris S. (2006): Comment on "Ivory-billed Woodpecker (Campephilus principalis) persists in continental North America". Science 311: 1555. doi:10.1126/science.1122778 PDF fulltext Supporting Online Material
- Steinberg, Michael K. (2008). Stalking the Ghost Bird: The Elusive Ivory-Billed Woodpecker in Louisiana. Louisiana State University Press ISBN 978-0-8071-3305-7
- Tanner, James T. (1942). The Ivory-Billed Woodpecker. National Audubon Society, N.Y.
- U.S. Fish and Wildlife Service (2005). Once-thought Extinct Ivory-Billed Woodpecker Rediscovered in Arkansas. 28 April 2005 Press Release. Retrieved 2006-OCT-6.
- Weidensaul, Scott (2005): Ghost of a chance. Smithsonian Magazine. August 2005: 97-102. Retrieved 2006-OCT-6.
- Winkler, H.; Christie, D. A. & Nurney, D. (1995): Woodpeckers: A Guide to the Woodpeckers of the World. Houghton Mifflin Company, Boston. ISBN 0-395-72043-5
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- "Annual Report of the ABA Checklist Committee: 2007 - Flight Path" (PDF). Retrieved 2012-11-13.
- "Wildlife Group Proposes $10,000 Reward For Ivory-billed Evidence". Eyewitness News everywhere. Clear Channel Broadcasting. 21 June 2006. Archived from the original on 28 August 2006. Retrieved 8 July 2006.
- Singer Tract is a dead link. Jack Hitt's Book Bunch of Amateurs says this was a huge tract of land in the South owned by the Singer Sewing Machine Company. Hitt says the land was bought for wood for sewing machine cabinets, was found too expensive to clear, but someone learned that WWII prisoners could clear it for very little money; ironically, the Ivory-billed Woodpecker's habitat was destroyed by Nazis.
- Robert C. Fleischer, Jeremy J. Kirchman, John P. Dumbacher, Louis Bevier, Carla Dove, Nancy C. Rotzel, Scott V. Edwards, Martjan Lammertink, Kathleen J. Miglia & William S. Moore (2006). "Mid-Pleistocene divergence of Cuban and North American ivory-billed woodpeckers". Biology Letters 2 (3): 466–469. doi:10.1098/rsbl.2006.0490. PMC 1686174. PMID 17148432.
- Leonard, Pat; Chu, Miyoko (Autumn 2006). "DNA Fragments Yield Ivory-bill's Deep History". BirdScope (Cornell Lab of Ornithology) 20 (4). Archived from the original on 5 June 2011.
- Jackson, Jerome (2002). "Ivory-billed Woodpecker". Birds of North America Online.
- Woodpeckers: An Identification Guide to the Woodpeckers of the World by Hans Winkler, David A. Christie & David Nurney. Houghton Mifflin (1995), ISBN 978-0-395-72043-1
- Hoose, Phillip M. (2004). The Race to Save the Lord God Bird. Douglas & McIntyre. ISBN 0-374-36173-8. "They gave it names like 'Lord God bird' and 'Good God bird'."
- Steinberg, Michael K. (2008). Stalking the Ghost Bird: The Elusive Ivory-Billed Woodpecker in Louisiana. LSU Press. ISBN 978-0-8071-3305-7. "Nicknamed the 'Lord God Bird', the 'Grail Bird', 'King of the Woodpeckers', and 'Elvis in Feathers', the ivory-bill -- thought to be extinct since the 1940s -- fascinates people from all walks of life and has done so for centuries."
- Jackson, Jerome (2002). "Ivory-billed Woodpecker". Birds of North America Online. Retrieved 11 October 2009.
- Arthur A. Allen and P. Paul Kellog "Recent Observations on the Ivory-Billed Woodpecker" The Auk, Vol. 54, No. 2 (Apr., 1937), pp. 164-184
- "Ecology and Behavior". The Cornell Lab of Ornithology.
- "Studying a Vanishing Bird". The Cornell Lab of Ornithology.
- "History of the Ivorybill: The Ivory-billed Woodpecker (Campephilus principalis), one of the largest woodpeckers known ... has become elusive to ornithologists as well as birdwatchers". ivorybill.org. Retrieved July 24, 2013.
- Smithsonian p 98
- Morris, Tim (9 January 2006). "the grail bird". lection. Retrieved 8 July 2006.
- Keith, Stuart (1983). "The Little-Known Status and Distribution of the Ivory-billed Woodpecker". Worldtwitch. Retrieved 8 July 2006.
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- Birdlife International (2005). "IUCN Red List — Species Information - Campephilus principalis". IUCN. Archived from the original on 22 November 2005. Retrieved 8 July 2006.
- Mayell, Hillary (20 February 2002). ""Extinct" Woodpecker Still Elusive, But Signs Are Good". National Geographic News. National Geographic. Retrieved 8 July 2006.
- Fitzpatrick, John W. (Summer 2002). "Ivory-bill Absent from Sounds of the Bayous". Birdscope. Cornell Lab of Ornithology. Retrieved 8 July 2006.
- J.W. Fitzpatrick et al., "Ivory-billed Woodpecker (Campephilus principalis) persists in continental North America," Science 308:1460-1462, 2005.
- reference needed
- "Listening for the Ivory-bill". Cornell Lab of Ornithology. Summer 2005. Archived from the original on 10 October 2006. Retrieved 25 March 2009.
- Dalton, Rex (2 August 2005). "Ivory-billed woodpecker raps on". BioEd Online. Retrieved 9 July 2006.
- J.A. Jackson, "Ivory-billed Woodpecker (Campephilus principalis): Hope, and the Interfaces of Science, Conservation, and Politics," Auk 123(1):1-15, 2006
- J.W. Fitzpatrick et al., "Clarifications about Current Research on the Status of Ivory-billed Woodpecker (Campephilus principalis) in Arkansas," Auk 123(2):587-593, 2006
- D. Sibley et al., "Comment on 'Ivory-billed Woodpeckers (Campephilus principalis) persists in North America," Science 311:1555, 2006
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Names and Taxonomy
Comments: Cuban form has been considered by some authors to be a distinct species, C. bairdii (AOU 1983). May constitute a superspecies with C. imperialis (AOU 1998).