The destruction that mankind is inflicting on the natural world is continuing at an ever-increasing rate, a new survey has shown. According to the “red list” compiled annually by the International Union for the Conservation of Nature, a fifth of the world’s known mammals, more than a quarter of amphibians and reptiles and a staggering 70 per cent of identified plants are now under threat of extinction.

The report also says that 12 per cent of all known birds, 37 per cent of freshwater fish and more than a third of invertebrates assessed so far are under threat. “The scientific evidence of a serious extinction crisis is mounting,” says Jane Smart, director of IUCN’s biodiversity conservation group.

“The latest analysis of the IUCN red list shows the 2010 target to reduce biodiversity loss will not be met. It’s time for governments to start getting serious about saving species and make sure it’s high on their agendas for next year, as we’re rapidly running out of time.”

Craig Hilton-Taylor, manager of the Red List Unit based in Cambridge, England, warned that the latest results were only “the tip of the iceberg”. He added: “We have only managed to assess 47,663 species so far; there are many more millions out there which could be under serious threat.

“We do, however, know from experience that conservation action works so let’s not wait until it is too late and start saving our species now.”For many species, however, conservation efforts are already too late. The Kihansi spray toad, for instance, which lived in southern Tanzania, is now believed to be extinct in the wild.

A dam upstream of Kihansi Falls has taken away 90 per cent of the water from the gorge where the toads used to live and a fungal disease has attacked the remaining animals. There are also fears that Rabb’s fringe-limbed tree frog might also now be extinct, with only one male traced in its central Panama home.

Although thousands of miles apart, the central American frog population has been devastated by the same fungal infection as the spray toad in Africa. Scientists believe that the infection has been spread by international trade and global warming.

Among mammals, critically endangered species include the western lowland gorilla and the bactrian camel. Of the world’s 5,490 mammal species, the IUCN believes that 79 are now extinct in the wild, 188 are critically endangered, 449 endangered and 505 vulnerable.

Dr Ben Collier, a research fellow at the London Zoological Society, whose scientists took part in the survey, said: “We must take decisive action to reverse the serious declines we see in wildlife. “We need to ensure that our enduring legacy is not to wipe out the small things that provide us with great benefits, such as nutrient recycling and climate regulation.”

Prof Andrew Lowe, a professor in plant conservation biology at the University of Adelaide in Australia, said that one of the features of this year’s list was the six-fold increase in the number of threatened freshwater fishes.

“When you’re looking to those kind of ecosystems, then they are really quite in poor health and largely because of conflicting demands for water by human populations,” he told ABC radio. What we see from areas from right across the world – from Africa, from the Americas, from Asia – is that species are suffering really unprecedented levels of threat.” Jean-Christophe Vié, deputy head of the IUCN species programme, acknowledged that creatures living in freshwater had been neglected for too long.

“This year we have again added a large number of them to the red list,” he said. “This reflects the state of our precious water resources. There is now an urgency to pursue our effort but, most importantly, to start using this information  to move towards a wise use of water resources.”