It's good news for the Guadalupe fur seal, the Bahian tree rat and the bridled nailtail wallaby, but animals are still dying out in a ‘sixth great extinction'.
The Guadalupe fur seal was feared extinct, gone the way of the dodo after being slaughtered by Russian and American hunters for their skins. None could be found at breeding grounds and as sightings elsewhere tailed off the species was consigned to history.
So why are there thousands of Guadalupe fur seals swimming off the coast of Mexico now? As naturalists gladly admit, reports of the species' demise at the end of the 19th Century were premature. Small numbers of the animals clung on in island caves and were rediscovered only decades later. The population is now thriving, with the latest estimate putting their number at 15,000 or more.
But the case of the Guadalupe fur seal is far from unique — and more animals feared extinct could be waiting to be rediscovered. A survey of the world's mammals published on September 29 reveals that more than a third of species once feared extinct have since been spotted in the wild, in one case 180 years after the last confirmed sighting. Rare mammals that were considered dead but later rediscovered were typically missing for 52 years.
The Guadalupe seal was hunted to apparent extinction by 1892, but a tiny colony was spotted on the island by two fishermen in 1926. After a failed attempt to sell two of the animals to San Diego zoo, one of the fishermen went back to slaughter the colony out of spite. He later turned up in Panama to sell the skins, but was killed in a bar brawl. The seals were only rediscovered and protected when a zoologist tracked down the second fisherman, who revealed their location on his deathbed in 1950.
One rodent, the Bahian tree rat, which lives in forests on the Brazilian coast, went missing in 1824. Despite efforts by conservationists, the animal was not rediscovered until 2004. The bridled nailtail wallaby was once common in eastern Australia but seemed to die out in the 1930s. It was spotted in 1973 by a contractor who was preparing to clear an area of land. After he raised the alarm, the habitat was bought by the local parks service to save the animal. Another creature, a small marsupial called Gilbert's potoroo, was missing for 115 years before it was rediscovered in the south of Western Australia in 1994.
Diana Fisher, who led the survey at the University of Queensland, said the number of mammals going extinct was still accelerating despite large numbers of lost animals being found.
‘In the grip of sixth extinction'
Conservation experts have already warned that the world is in the grip of the “sixth great extinction”, as imported species and diseases, hunting and the destruction of natural habitats deal a fatal blow to plants and animals.
Writing in the journal Proceedings of the Royal Society B, Fisher lists 180 mammals reported as extinct, feared extinct, or missing since the year 1500. Of these, 67 were later found to be alive and well. Animals that were picked off by new predators were rarely rediscovered, while those threatened by a loss of habitat or hunting by humans were more likely to be holding on in small colonies, she found.
The survey highlights the uncertainties in lists of extinct species, but Fisher said it should help conservationists target their searches for missing species by focusing on those most likely to be alive.
More than 25 large-scale searches have failed to find thylacines, the carnivorous, dog-like marsupials that have not been seen in Australia for nearly 80 years.
Fisher said her analysis puts the chance of the species surviving at “virtually zero”. Mammals that were hunted to extinction before the 20th Century, such as the Steller's sea cow, the Falkland Islands wolf, the sea mink and the large Palau flying fox are also unlikely to be found now, Fisher said.
“Conservation resources are wasted searching for species that have no chance of rediscovery, while most missing species receive no attention,” Fisher said. “Rather than searching ever more for charismatic missing species, such as thylacines in Australia, it would be a better use of resources to look for species that are most likely to be alive, find out where they are, and protect their habitats,” she added.
According to Fisher's survey, the most likely missing mammals to be found alive are the Montane monkey-faced bat in the Solomon Islands, the Alcorn's pocket gopher, which was last seen in the high forests of Mexico, and the lesser stick-nest rat, a large, soft-furred desert animal from Australia. — © Guardian Newspapers Limited, 2010