Associated Press: Here on the endlessly rolling and tussocky terrain of northwest Canada, where man has hunted caribou since the Stone Age, the vast antlered herds are fast growing thin. And it’s not just here. Across the tundra 1,500 kilometers (1,000 miles) to the east, Canada’s Beverly herd, numbering more than 200,000 a decade ago, can barely be found today. Halfway around the world in Siberia, the biggest aggregation of these migratory animals, of the dun-colored herds whose sweep across …