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Biodiversity Insights > Rediscovery of the Ivory-Billed Woodpecker
When “Extinct” is Not the Final Word
Ivory-billed Woodpecker, 19th-century illustration by Alexander Wilson.
April 28, 2005 — The ivory-billed woodpecker (Campephilus principalis), long thought to be extinct, has been rediscovered in Arkansas, according to a paper published today in the journal Science. Although never abundant, less than a century ago the ivory-billed was widely distributed across the southeastern United States, and was also found in Cuba. The loss to logging of its favored habitat of swampy bottomland forest caused its decline and apparent disappearance in the U.S. The bird survived in the rugged mountains of eastern Cuba through at least the late 1980s, but no confirmed sightings had been made since.
Discoveries and Rediscoveries
What does the exciting news of the rediscovery of the ivory-billed tell us about the concept of extinction and how scientists make such determinations? NatureServe and our network of natural heritage programs in every state continually assess the condition and conservation status of U.S. plants, animals, and ecological communities. More than half a million precise localities for at-risk species are documented in our comprehensive databases.
While the ivory-billed woodpecker represents the most sensational example of a rediscovery, throughout the NatureServe network discoveries and rediscoveries happen regularly. Over the years natural heritage program surveys have found at least 43 species of plants and animals new to science, while another 24 missing species—those, like the ivory-billed, thought to be possibly extinct—have been rediscovered. (On May 26, the rediscovery of another missing species was announced. The Mount Diablo buckwheat (Eriogonum truncatum), last seen in 1936, was found on state park land in Contra Costa County, California). The news of the ivory-billed woodpecker highlights the importance of biological inventories and research as the foundation for knowledge about conservation issues. The Arkansas Natural Heritage Program is a partner in the research effort and has been working closely with The Nature Conservancy to prioritize lands for acquisition of potential ivory-billed woodpecker habitat.
Documenting extinctions presents a difficult challenge. Whereas the existence of a species can be documented directly and unambiguously—sightings, specimens, or telltale signs—the absence of a species often must be inferred from circumstantial evidence. In documenting extinctions, we are dealing with negative information—looking for what isn’t rather than what is.
[NatureServe] conservation status ranks provide a consistent way of evaluating the condition of species, and special care is given to distinguishing those plants and animals that are, or may be, extinct. Because of the inherent difficulties of documenting extinctions, we are very conservative in our approach. A species is not classified as “presumed extinct” (conservation status rank of GX) unless exhaustive searches of all suitable habitat have been carried out and there is no more cause for hope. The more cautious category of “possibly extinct,” or “historical” (GH), is used for species that have not been sighted in many years or whose only recorded occurrences are known to be destroyed—species that warrant further searches before being given up for gone.
A total of 539 U.S. species are recorded [by NatureServe] as extinct or missing [note: these data are as of 2000]. Of these, 100 meet the stricter criteria of presumed extinct, with another 439 falling into the possibly extinct category. These extinctions span the gamut of organisms, including vertebrates such as the great auk and West Indian monk seal, plants like the Santa Catalina monkeyflower and falls-of-the-Ohio scurf-pea, and invertebrates such as the Wabash riffleshell and the Colorado burrowing mayfly.
Excerpted from pp. 113-114 of Precious Heritage: The Status of Biodiversity in the United States (Oxford University Press, 2000). Produced by NatureServe and The Nature Conservancy. Edited by Bruce A. Stein, Lynn S. Kutner, and Jonathan S. Adams.
For a full description of how NatureServe assesses conservation status and assigns status ranks to species, see NatureServe Conservation Status.
Bird Extinctions in the United States
In the United States, there have been more extinctions of birds than of any other group of vertebrates. The most current NatureServe data, as reflected in our NatureServe Explorer online database, show 30 birds in all that are either presumed extinct (GX) or missing and possibly extinct (GH). [See list.] The majority of these birds (23) were native only to Hawaii. Of the seven species native to the continental United States, four are presumed extinct: the passenger pigeon, Carolina parakeet, Labrador duck, and great auk. With the rediscovery of the ivory-billed woodpecker, the two remaining missing and possibly extinct birds of the continental United States are Bachman’s warbler and the Eskimo curlew. The NatureServe conservation status for the ivory-billed woodpecker will now be changed from GH to G1 (critically imperiled).
Extinctions by State
Click here for a table showing the number of extinct species in each state. (From the report States of the Union: Ranking America's Biodiversity. NatureServe. April 2002).