The Porcupine Caribou Herd is known internationally as one of the largest migratory caribou herds in North America. The herd of currently over 160,000 animals migrates through about 250,000 km2 of northern Alaska, Yukon and Northwest Territories, between their calving grounds in the Arctic National Wildlife Refuge on the coastal plains of Alaska, and their winter range in northern Yukon. This is one of the longest migration routes of any land mammal on the planet.
First Nations in these northern climes rely on caribou. Porcupine Caribou have been the mainstay for people in the region for upwards of 20,000 years and were hunted by ancestors of today's Gwich'in, Northern Tutchone, Han, Inuvialuit and Inupiat peoples. In traditional times, the caribou's migration patterns determined the location of seasonal communities. Although First Nations' lifestyles are now a blend of ancient traditions and modern technologies, the Porcupine Caribou remain a vital part of northern culture and the regional economy.
Much of the Peel watershed falls within the Porcupine Caribou herd's winter range, providing important seasonal habitat. Their diet consists mainly of lichens and the evergreen low-bush cranberry shrub, supplemented by moss, grasses and other small shrubs. Since caribou have to dig holes or 'feeding craters' in the snow to find these plants, they seek undisturbed areas of reduced snow cover, south slopes and windswept mountain ridges to locate winter food. The Peel watershed wilderness provides food in abundance away from the disruptive influences of development.
The main predators of caribou are wolves and humans. Wolf numbers are relatively low and do not have a large effect on caribou populations. Similarly, human hunters take a small percent of the herd each year. In the past twenty years, however, a serious and unexplained decline in numbers prompted the Porcupine Caribou Management Board to implement a harvest management plan and other conservation efforts to redress the loss. These efforts have helped reverse the decline that had cut the herd by nearly a third. Initial results of the 2010/2011 photo census indicate a population of 169,000 animals; figures not seen since the early 1990s. However, pressures on the herd continue to grow and could potentially hinder this revival. Climate change and, in particular, the higher snowfall and predicted greater number of thaw days will result in harsher travelling and feeding conditions for caribou. Warmer weather could lead to more insect harassment in summer.While the importance of the calving grounds within the Arctic National Wildlife Refuge is well documented, research suggests that wintering grounds may be equally essential to the herd's future. However, the potential impacts of development in the winter habitat are different and less understood.