Almost 10 per cent of known species are threatened with extinction, according to the first comprehensive study of the world's wildlife. Polar bears, whose habitat is threatened by melting ice, and Tasmanian devils, which have been pushed to the brink of extinction by a cancer, are just two of the tens of thousands of mammals, birds, reptiles, fish and amphibians that are in danger. The report, The Number of Living Species in Australia and the World , published by the Australian Biological Resources Study (ABRS), says that 9.2 per cent of known animal species are endangered by habitat loss, climate change and other pressures. More than a fifth of of all known mammals are endangered, as are 29 per cent of amphibians and 12 per cent of birds, according to the study, the result of an international effort to catalogue every known current and extinct species of plant and animal. So far, 1.9 million species have been identified, but the authors believe that figure could swell to 11 million, as vast numbers of invertebrates, fungi and other organisms have yet to be found, classified and named. In the past month British scientists helped to discover at least 40 new species in the rainforests of Papua New Guinea, including 16 frogs, a bat and a giant rat, which may turn out to be the biggest in the world. The study's estimate that there are 11 million species is towards the lower end of previous scientific projections, which have put the figure at between three million and 100 million. In part that may be because of DNA sequencing, which has made the task of distinguishing species much easier, especially among smaller creatures. A biodiversity index may eventually be produced on the basis of the project measuring mankind's progress in protecting plants and animals � a kind of Dow Jones index of the planet's flora and fauna. The study also adds to the growing weight of scientific knowledge about the problems faced by the world's wildlife and provides a broader context for the International Union for the Conservation of Nature's Red List, an annual report that focuses on which species are most in danger of extinction. Cameron Slatyer, the ABRS director, co-ordinated the study with more than 50 scientists around the world, including experts from the Natural History Museum in London. He said: "This report gives the Red List more meaning because until you have some estimate of the detail of biodiversity on the planet, you cannot quantify how serious the extinction threat is."