Just as new species are being discovered, some extinct species occasionally do get rediscovered. A group led by Diana Fisher at the University of Queensland has surveyed rediscoveries of mammalian species thought to be extinct, among them the Guadalupe fur seal of Mexico and the Bahian tree rat of Brazil. Their conclusion? Stop wasting time by trying to look for charismatic, but dead-as-a-dodo, species like the Australian thylacine, and concentrate efforts on smaller, often well-concealed, species that are more likely to be alive.
Despite these rediscoveries, the news is not very hopeful, though. Most of these species persist as small populations in refugia which might eventually be destroyed because of clearing and land conversion. This piece of news by no means should be taken to mean that species are recovering, only that our knowledge of the natural world is incomplete, and this incompleteness extends to the extinct as much as it does to the extant.