• More than third of missing animals are rediscovered
• Bahian tree rat found 180 years after last sighting
Ian Sample, The Guardian 28 Sep 10;
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 today 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 in 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.
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 Steller's sea cow, the Falkland Islands wolf, 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 told the Guardian. "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, 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.
Four other 'extinct' species
Bahian tree rat
A small rodent that lives in the coastal forests of Brazil. Was missing and presumed extinct for 180 years from 1824. A year-long search of the area in 2004 found only one of the animals living in the region. The species is critically endangered and is considered at threat from ongoing deforestation.
Bridled nailtail wallabyOnce common in eastern Australia, this nocturnal species, below left, was thought to have died out in 1930. The animal was rediscovered in Queensland after a contractor recognised it from a picture of extinct creatures published in a women's magazine. It gets its name from the horny, pointed tip on its tail. It was hunted for its fur, but more recent threats include foxes and habitat loss. It remains endangered.
Gilbert's potoroo
A small, silky-coated marsupial that was missing in Australia from 1879 to 1994, when conservationists found a tiny population of the animals in the Two People's Bay park area in the west of the country. The animal is likely to have survived because the reserve was already protected to save the habitat of a rare bird. The potoroo suffered from predation by cats and foxes that were introduced to the area. Those that remain are genetically very similar, leaving them vulnerable to diseases. It is one of Australia's rarest animals.
Leadbeater's possumA grey marsupial with black markings. Leadbeater's possum, below right, was known from only four specimens collected around 1900. It was considered extinct in 1920 when its habitat was destroyed, but was rediscovered in 1961 during a survey of a mountain forest in Victoria. The population stands at around 2,000 adults, a number that is expected to fall by 90% in 30 years as den trees and nesting habitat are lost.
A Third of ‘Extinct’ Mammals May Still Be Alive
Brian Switek Wired Science 29 Sep 10
There may be many more “extinct” mammals waiting to be rediscovered than conservation biologists previously thought.
Categorizing a mammal species as extinct has rested upon two criteria: It has not been seen for more than 50 years, or an exhaustive search has come up empty. But “extinct” species occasionally turn up again, and some species have disappeared more than once. Australia’s desert rat kangaroo, for example, was rediscovered in 1931 after having gone missing for almost a century, only to disappear again in 1935 when invasive red foxes moved into the area of the remaining survivors.
In order to determine how often extinct species had been rediscovered, University of Queensland scientists Diana Fisher and Simon Blomberg created a dataset of 187 mammal species that have been reported extinct, extinct in the wild, or probably extinct since 1500, as well as those which have been rediscovered. They also looked at historical data on the threats that caused species to become extinct — or brought them close to it — including habitat loss, introduced species and overkill by humans.
It turns out that rumors of the extinction of more than a third of these species have turned out to be premature, the scientists report in Proceedings of the Royal Society B Sept. 29. At least 67 species — a little more than a third of those presumed to be extinct — were later found again. And in most cases, these were animals that had been hardest hit by habitat loss.
Humans and invasive species have been significantly more efficient killers. It’s rare that a species reported extinct due to one of these causes has been seen again.
“If you think that a missing species is extinct and the main cause of decline was introduced predators such as feral foxes, cats or rats, then you are very likely to be right,” Fisher said. But, she added, “If the main cause of decline was habitat loss, you are quite likely to be wrong if you say that it’s extinct, unless it was restricted to a very small area.”
As an example, Fisher cites the Malabar civet, which was thought to be extinct due to habitat loss in 1929 but survived in marginal areas at least until 1987 when it was last seen on a cashew plantation. Unfortunately, that animal was killed by villagers, and no more have been seen since.
The team found species that were relatively sparsely distributed over a larger range were more likely to turn up again. But mammals of any particular evolutionary group or body size weren’t more likely to be rediscovered.
"I was a little bit surprised that body size was not important,” Fisher said. “I thought that small species might not be found so often, because they don’t attract much attention, but that wasn’t the case.”
With these findings in hand, conservation biologists may be better able to target species that are more likely to still be out there somewhere. While species hunted into extinction — such as the Stellar’s sea cow — are almost certainly gone forever, individuals of other species may still exist. Whether we find them again or not seems to be directly influenced by how hard we look.
According to Fisher and Blomberg, one or two searches for a missing species aren’t likely to succeed, but missing species that were the subject of three to six searches have often been rediscovered. Chances do not continue to get better past this point, though. Species that have been the subject of more than 11 searches, such as the Tasmanian tiger and the Yangtze dolphin, have not been found.
We may hope for the rediscovery of such charismatic species, but the chances of finding some of the lesser-known species that haven’t been looked for yet are significantly better. Among the good candidates for rediscovery Fisher lists are the Montane monkey-faced bat of the Solomon Islands, last seen on Guadalcanal in 1990, and Alcom’s pocket gopher, which was abundant in a high-elevation forest in Mexico in the late 1990’s but hasn’t been seen since.
“We should be trying to protect the habitat of recently extinct species,” Fisher said. “But this is not easy, because we don’t know where they might be rediscovered. It is not necessarily near where the species was last seen.”
Gilbert’s potoroo, for example, disappeared sometime around 1879 but was rediscovered in 1994 at Two People’s Bay in Australia in a reserve that had been set up to protect an endangered bird. Because many rediscovered species had populations that were spread over a wide area, ecologists have a lot of ground to cover in their search for “extinct” mammals.
Study Shows How Scientists Can Find Missing Species
David Fogarty PlaneArk 30 Sep 10;
More than a third of mammal species considered extinct or missing have been rediscovered, a study says, and a lot of effort is wasted in trying to find species that have no chance of being found again.
Species face an accelerated rate of extinction because of pollution, climate change, habitat loss and hunting and that this rate of loss is putting ecosystems and economies at ever greater risk, according to the United Nations.
Researchers at the University of Queensland in Australia said a greater understanding of patterns of extinction could channel more resources to finding and protecting species listed as missing before it's too late.
"In the past people have been very happy to see individual species found again but they haven't looked at the bigger picture and realized that it's not random," university research fellow Diana Fisher, lead author of the study, told Reuters.
Fisher and her colleague Simon Blomberg studied data on rediscovery rates of missing mammals to see if extinction from different causes is equally detectable. They also wanted to see which factors affected the probability of rediscovery.
They found that species affected by habitat loss were much more likely to be misclassified as extinct or to remain missing than those affected by introduced predators and diseases.
"It is most likely that the highest rates of rediscovery will come from searching for species that have gone missing during the twentieth century and have relatively large ranges threatened by habitat loss," they say in the report in the Proceedings of the Royal Society B journal.
The United Nations hosts a major meeting in Japan next month at which countries are expected to agree on a series of 2020 targets to combat the extinctions of plants and animals key to providing clean air and water, medicines and crops.
"Conservation resources are wasted searching for species that have no chance of rediscovery, while most missing species receive no attention," the authors say, pointing to efforts to try to find the Tasmanian tiger.
The last known living Tasmanian tiger, marsupial hunter the size of a dog, died in 1936 in a zoo.
Fisher told Reuters efforts to find missing species have led to success stories of animals and plants being rediscovered and the creation of protection programmes.
But the rediscoveries barely make a dent in the rate of species loss overall, Fisher said by telephone.
"The number of additions every year outweighs the number of that have been rediscovered. There's still an accelerating rate of extinctions every year of mammals.
Read more!
Posts
visitors since Nov 07