This Aug. 12, 2009 photo shows migrating Caribou in the Porcupine River Tundra in the Yukon Territories, Canada. 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. (AP Photo / Rick Bowmer)

By CHARLES J. HANLEY (AP) ON THE PORCUPINE RIVER TUNDRA, Yukon Territory — 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 the Arctic’s white canvas is one of nature’s matchless wonders, has shrunk by hundreds of thousands in a few short years. From wildlife spectacle to wildlife mystery, the decline of the caribou — called reindeer in the Eurasian Arctic — has biologists searching for clues, and finding them. They believe the insidious impact of climate change, its tipping of natural balances and disruption of feeding habits, is decimating a species that has long numbered in the millions and supported human life in Earth’s most inhuman climate. Many herds have lost more than half their number from the maximums of recent decades, a global survey finds. They “hover on the precipice of a major decline,” it says. The “People of the Caribou,” the native Gwich’in of the Yukon and Alaska, were among the first to sense trouble, in the late 1990s, as their Porcupine herd dwindled. From 178,000 in 1989, the herd — named for the river crossing its range — is now estimated to number 100,000. “They used to come through by the hundreds,” James Firth, 56, of the Gwich’in Renewable Resources Board said as he guided two Associated Press journalists across the tundra. Off toward distant horizons this summer afternoon, only small groups of a dozen or fewer migrating caribou could be seen grazing southward across the spongy landscape, green with a layer of grasses, mosses and lichen over the Arctic permafrost. “I’ve never seen it like this before,” Firth said of the sparse numbers. … “The numbers are not getting better. There’s no good news, no indication of recovery,” J. Michael Miltenberger, the environment and natural resources minister, said by telephone from Yellowknife, the capital. …

Mighty caribou herds dwindle, warming blamed