The big migration. Tens of thousands of caribou head West across the Arctic National Wildlife Refuge en route to Canada’s Yukon Territory. The Arctic has warmed twice as much as anywhere else on Earth. This means less snow pack which means less protection for the caribou to hide from the ever increasing hungry populations of mosquitos. I once stood next to a caribou that had gone completely crazy from swarms of voracious insects. His eyes showed fear and he bucked his emaciated frame wildly. Some caribou populations have been decreasing dramatically whereas this Porcupine herd has been inching up in recent years.- photo by paul nicklen