The video images may be tiny, grainy, dark and fleeting, but many looking at them see something glorious: evidence that at least one ivory-billed woodpecker--an 18- to 20-inch-tall bird with a wingspan of some 30 inches, last seen in the U.S. in 1944--is alive in the bottomland forest of eastern Arkansas. After a year of traipsing and canoeing through the Big Woods and its bayous, many inconclusive recordings of ivory-bill-like calls, seven good sightings and one fortuitous videotaping, scientists and conservationists announced in April that the bird was not extinct after all.

If the discovery holds up, the ivory-billed woodpecker will not be the only U.S. species recently returned from oblivion. In May, just a few days after the ivory-bill news, the Nature Conservancy announced the discovery in Alabama of three snails listed as extinct. A few weeks later, botanists at the University of California at Berkeley reported finding the Mount Diablo buckwheat, a tiny pink-flowered plant that had not been seen since 1936. At least 24 species of other presumed or possibly extinct plants, insects and other organisms have been found during natural heritage surveys in North America since 1974, according to Mark Schaefer, president of NatureServe, a nonprofit conservation group based in Arlington, Va. There are examples from elsewhere as well. The Bavarian pine vole, last seen in 1962, scurried back into view in 2000. The New Zealand storm petrel and the Lord Howe Island stick insect are among the other species no longer missing.

With so many "extinct" creatures reappearing, it is reasonable to wonder if the word has lost its meaning--something Ross MacPhee, curator of mammalogy at the American Museum of Natural History, has been outspoken about. He worries that complacency may set in (if it hasn't already), because many species that people read or hear about are described as either on the verge of extinction, already extinct or formerly extinct. He cites the example of Miss Waldron's red colobus monkey, extinct in 2000, alive in 2004. "The average person has been barraged with the same story over and over again," he says. "People are using the term indiscriminately."

To counteract this trend, MacPhee and his colleagues formed the Committee on Recently Extinct Organisms in the late 1990s, devising criteria to determine extinction reliably--including rigorous taxonomic identification and a 50-year waiting period before declaring something extinct, an idea first put forth by the Convention on International Trade in Endangered Species.

Schaefer and John W. Fitzpatrick of Cornell University, lead author of the ivory-billed woodpecker report, agree that "extinction" should be applied more carefully. "The word 'extinct' is an absolute term, like pregnant or dead," Fitzpatrick remarks, "so we need to describe the probability of that being true." In cases such as the passenger pigeon, which has not been seen by anybody for nearly a century, "we treat it as formally extinct," he notes. For many plants and small vertebrates, "we suspect extinction, but they may still be hiding in some spots. That was the case for the ivory bill." Schaefer says that his organization has a letter scheme to describe species as GX (presumed extinct) or GH (possibly extinct) and then uses several other classifications, such as G1 (critically imperiled)--ranks also used by various federal agencies.

For now, the ivory-billed woodpecker seems to have been successfully upgraded. But "speaking probabilistically, this bird has a very, very slim chance of persisting," Fitzpatrick points out. "The key lies in growing back the old forest. That is exactly what this bird needed. Unlike in other cases of extreme endangerment, like Hawaii, the ivory bill is a case in which the natural habitat of the bird is getting progressively better. And I would add that even if the ivory bill fails, we should accelerate the process."