One in eight bird species is threatened with extinction, including some familiar ones like barn swallows and purple martins, a report released in Canada said. Birdlife International released the report, based on data from more than 120 affiliated national bird organizations, at its 2013 Congress in Ottawa Thursday. The main factors in the extinction threats are unsustainable agriculture and climate change, experts said. \"Unless we take action now to improve their fortunes, these are species that are going to go extinct in the coming years,\" Stuart Butchart, Birdlife International\'s chief scientist, said. He cited as an example Southeast Asia and Africa, where huge tracts of tropical forests are being cut down and replanted with oil palms. \"Natural habitats are being converted and many, many species are losing large parts of their population and their range,\" Butchart said. As of 2011, 1,253 bird species (12.5 percent of the total, or one in eight) are globally threatened with extinction because of their small and declining populations or ranges, the Birdlife International report said, and of these 189 species are Critically Endangered, meaning they face an extremely high risk of extinction in the immediate future. The loss of bird species is a warning about the vulnerability of all the natural world, he said. \"Birds are fantastic indicators. They are good at telling us where other wildlife is found and their trends also closely mirror what\'s happening to other wildlife groups,\" he said. \"So the fact that many bird species are declining, many are threatened with extinction, really should be ringing alarm bells.\"