Canada needs to create large protected areas of woodlands to help save caribou from the threat of extinction, scientists and environmentalists said Wednesday. In a study on the plight of the caribou in Canada\'s vast boreal forests, international experts said an area between 10,000 to 15,000 square kilometers (3,860 to 5,790 square miles) was needed -- about half the size of Belgium. \"These scientists advise that very large protected areas need to be established across Canada\'s boreal region in order to maintain the levels of intact boreal habitat necessary for this species to persist,\" two experts said in a letter. Writing to Canadian Prime Minister Stephen Harper, the two scientists Steve Kallick and Larry Innes also called for a national dialogue \"to develop a collective plan of action before important options are foreclosed by poorly planned development.\" Caribou have been on the list of Canadian species threatened by extinction since 2000 with the population of the majestic, antlered beasts rapidly declining over the past 150 years in Canada and northern Europe. According to figures from the Canadian environment ministry from 2008, there were only some 30,000 to 40,000 caribou living in Canadian forests, mainly in Quebec, Ontario and the North Western Territories. The animals main predators are wolves and black bears and bear some blame for their falling numbers, but \"the ultimate cause is human activities,\" a 12-page policy study said. \"This species requires exceptionally large areas of relatively old and intact forest habitat, not only for the slow-growing lichens that serves as winter food, but also for the space to avoid predators,\" it added. Mining, oil and gas projects, as well as logging and road construction have all gobbled up the caribou\'s natural habitat. \"There is now wide agreement on what needs to be done, and while we cannot put a timeline on it, it is clear that failure to act will place these iconic animals on the road to extinction,\" Jeffrey Wells, senior advisor to the Pew Environment Group and a co-author of the policy brief, told AFP.