Conservationists are overestimating the number of species that have been driven to extinction, scientists have said. A study has found that a third of all mammal species declared extinct in the past few centuries have turned up alive and well. Some of the more reclusive creatures managed to hide from sight for 80 years only to reappear within four years of being officially named extinct in the wild.
The shy okapi – which resembles a cross between a zebra and a giraffe – was first discovered in the Democratic Republic of Congo in 1901.
After increasingly rarer sightings, it vanished from the wildlife radar for decades from 1959, prompting fears that it had died out.
But five years ago researchers working for the WWF found okapi tracks in the wild.
Other mammals ‘back from the dead’ include the rat-like Cuban solenodon, the Christmas Island shrew, the Vanikoro Flying Fox of the Solomon Islands, the Australian central rock rat and the Talaud Flying Fox of Indonesia.
The revelations come as the world’s leading conservationists prepare for a major United Nations summit on biodiversity in Nagoya, Japan, next month.
Many scientists believe the world is going through a new ‘mass extinction’ fuelled by mankind – and that more species are disappearing now than at any time since the dinosaurs vanished 65million years ago.
According to the International Union for the Conservation of Nature, 22 per cent of the world’s mammals are at risk of extinction. In Britain, more than two plant and animal species are being wiped out each year.
But while the report does not play down the threat from deforestation, overfishing or habitat destruction, it raises questions about the way species are classified as extinct.
Dr Diana Fisher, of the University of Queensland, Australia, compiled a list of all mammals declared extinct since the 16th century or which were flagged up as missing in scientific papers.
‘We identified 187 mammal species that have been missing since 1500,’ she wrote in the journal Proceedings of the Royal Society B.
‘In the complete data-set, 67 species that were once missing have been rediscovered.
More than a third of mammal species that have been classified as extinct or possibly extinct, or flagged as missing, have been rediscovered.’
Mammals that suffered from loss of habitat were the most likely to have been declared extinct and then rediscovered, she said.
Species spread out over larger areas were also more likely to be wrongly classified as extinct.
The mistakes cannot be blamed on primitive technology or old fashioned scientific methods.
‘Mammals missing in the 20th century were nearly three times as likely to be rediscovered as those that disappeared in the 19th century,’ Dr Fisher added.
