Approximately one in four species of land mammal and one in three marine mammal species are at risk of extinction, according to a major new study. The research, which was carried out by some 1,800 scientists in 130 countries, was presented at the IUCN (International Union for the Conservation of Nature) World Conservation Congress in Barcelona, Spain, and is set to be published in a forthcoming edition of the journal Science. The scientists gathered detailed information on each species' taxonomy, distribution, habitats, population trends and ecology, as well as information on human use of the species and conservation measures. The assessment represents the first comprehensive investigation of the health of terrestrial and marine mammals around the world. The analysis reveals that at least 1,141 of the world's 5,487 mammal species are threatened with extinction, and 188 species are listed as 'critically endangered', the highest threat category. These include Europe's Iberian lynx (Lynx pardinus), whose population has shrunk to between 84 and 143 individuals. The list also includes 29 species which are listed as 'possibly extinct'. 'Within our lifetime, hundreds of species could be lost as a result of our own actions, a frightening sign of what is happening to the ecosystems where they live,' says Julia Marton-Lefèvre, IUCN Director General. 'We must now set clear targets for the future to reverse this trend to ensure that our enduring legacy is not to wipe out many of our closest relatives.' Habitat loss and degradation are the main drivers of this crisis, affecting 40% of the world's mammals, most notably in central and South America, Africa, Madagascar and south and southeast Asia. Over-exploitation is also a major threat for large mammals, especially in southeast Asia, where 79% of primate species are threatened with extinction. In our seas, marine mammals are predominantly threatened by pollution, global warming and overexploitation. However, this new Red List is not all bad news, as it demonstrates that some species can and do come back from the brink of extinction. Examples include the wild horse (Equus ferus), which was listed as extinct in the wild just 10 years ago. Following a successful reintroduction programme in Mongolia, it is now in the 'critically endangered category'. Similarly, the African elephant (Loxodonta africana) moved from the 'vulnerable' to 'near threatened' category thanks to large increases in numbers in southern and eastern Africa. Despite their best efforts, the scientists had difficulty gathering data on over 800 mammal species, meaning the total number of endangered species could be even higher. 'The reality is that the number of threatened mammals could be as high as 36 percent,' says Jan Schipper of Conservation International and lead author of the forthcoming article in Science. 'This indicates that conservation action backed by research is a clear priority for the future, not only to improve the data so that we can evaluate threats to these poorly known species, but to investigate means to recover threatened species and populations.' Andrew Smith of Arizona State University in the US, co-author on the study, explained why maintaining healthy mammal populations is so important. 'Mammals are important because they play key roles in ecosystems and provide important benefits to humans,' he explained. 'If you lose a mammal, you often are in danger of losing many other species.' The IUCN's Red List now contains over 44,000 species, of which almost 17,000 (38%) are threatened with extinction.