Every summer the Western Arctic caribou herd congregates in northern Alaska for one of the world’s most inspiring wildlife migrations. The Western Arctic Caribou Herd is the epitome of this kind of boundless migration. Caribou migration routes are often located in areas where shallow or hard snow or frozen rivers and lakes facilitate travel [ 18 – 21 ], and adverse snow conditions may delay migration by hindering caribou movements [ 22 ]. A draft EIS is expected in 2019 for the Willow development project within the Teshekpuk Caribou Herd’s range in the northeastern NPR-A, and there will be opportunities for public comment. The Western Arctic Caribou Herd Working Group is comprised of representatives from communities within the Western Arctic Herd range, other Alaska hunters, guides, transporters, conservationists, and reindeer herders. Porcupine caribou's (R. t. granti) 1,500 miles (2,400 km) annual land migration between their winter range in the boreal forests of Alaska and northwest Canada over the mountains to the coastal plain and their calving grounds on the Beaufort Sea coastal plain, is the longest of any land mammal on earth. The Porcupine Caribou herd is one of the largest migratory barren ground caribou herds in North America. ... Because Arctic Alaska is so vast and the caribou vary their route from year to year, it can be difficult to plan a trip to see this wildlife spectacle. Development within the Range of the Western Arctic Caribou Herd. There are at present 13 caribou herds in Alaska, including two introduced populations. It is a thrilling experience to watch a valley fill with caribou. Caribou from the Western Arctic Herd flood across the Onion Portage of the Kobuk River twice a year, moving between winter and summer grounds and back again. This project would expand development west into the Bear Tooth Unit from existing NPR-A developments in the Alpine and Greater Mooses Tooth Units. Calving takes place on the Arctic Coastal Plain, and by late summer (August) calves are strong enough to begin the migration to wintering grounds to the south. Migration is an important component of the life history of many animals, but persistence of large-scale terrestrial migrations is being challenged by environmental changes that fragment habitats and create obstacles to animal movements. The Western Arctic Caribou Herd In March and April barren-ground caribou begin their great migration, small groups join together and long lines form as they move steadily north.The Western Arctic Caribou Herd ranges over a territory bounded by Prudhoe Bay on the north, south to the Yukon River and west to Unalakleet on the Seward Peninsula. The total caribou population of Alaska exceeds 600,000. (National Park Service) Caribou and reindeer travel the longest distance while migrating on land, a new study shows. Western Arctic Herd (WAH) has greatly shaped the heritage and traditions of the communities that depend on the herd for subsistence. Calf survival is higher in these traditional calving grounds, and females nursing their young need relief, and migration routes for the 490,000-strong Western Arctic caribou herd—Alaska’s largest. Join us on our hike from the mountains to the sea. Caribou from the Western Arctic Caribou herd migrate south through the DeLong Mountains in the Western Brooks Range in Alaska’s Arctic in a 2012 file photo.