Abstract
Across their circumpolar ranges, many herds are being exposed more frequently to industrial exploration and development, leading to concerns about the cumulative effects of such exposure. For example, caribou change their habitat use in the vicinity of roads, oilfields, and mines. Additionally, a shift to wage earning in user communities can affect harvest levels by increasing the demand for caribou meat. Increased income allows harvesters more choice in harvesting methods, such as taking advantage of winter and all-season roads, and technological advances allow caribou to be located more easily. The post-calving ranges of the Beverly herd have recently seen a boom in uranium exploration, raising strong concerns about the effects of those activities on caribou abundance. In the 1990s, high levels of exploration for diamonds on the post-calving ranges of the Bathurst herd culminated in the construction of four diamond mines. Currently, there is a concern about oil and gas exploration activities on the winter ranges of the Bluenose East and Bluenose West caribou herds in the Northwest Territories. The most conspicuous ecological strategy is seasonal migration. These migrations are the key for wild reindeer and caribou to take advantage of the shifting patterns of forage availability while at the same time spacing themselves to reduce exposure to predation and parasitism. For the few herds for which we have enough data, we are just starting to appreciate how other ecological strategies vary between herds, especially those that link movements and foraging to survival and reproduction. The Porcupine caribou herd, migrating across the borders of the Yukon, the Northwest Territories, and Alaska, enters its winter range with relatively little back fat, having devoted summer resources to raising relatively large calves. These caribou are able to remain successful despite their small overwinter reserves because of the typically low snow and abundant lichens in the region. However, once north of the tree line on spring migration, the pregnant cows leave lichen areas and feed on evergreen shrubs and moss until fresh green vegetation emerges from under the snow. The emergence of new vegetation typically occurs at or within a week of calving, when their nutritional demands peak. The cows arrive on the calving grounds with low body reserves, and the timing and progression of green-up largely determines the fate of their newborns within the first month after birth. The rapid green-up after snowmelt offers nursing cows abundant nitrogen-rich forage, essential for milk production, and we have already seen that warmer springs have increased early calf survival in the Porcupine herd. The future focus of management should be to foster resilience in caribou herds, to increase their capacity to cope with climate change and the changing economic and social settings. This focus requires defining resilience with performance-based criteria to ensure that management is adaptive, effective, and measurable. CARMA's tools and comprehensive herd assessments will contribute toward monitoring and understanding those effects whose total is summarized as resilience-the capability of individual caribou or the herd to cope with environmental change, as well as the capacity of the co-management system to translate findings into a collective will to act. Individual measures include levels of fat reserves, or rates of pregnancy and calf survival, while frame-size measures are indicative of population responses. Landscapes (seasonal ranges) where caribou are not impeded from freely undertaking both seasonal migrations and local movements, either to reduce exposure to predators and parasites or to forage efficiently, will be crucial to building individual and herd resilience. Fostering resilience in herds is tied to institutional arrangements that are collaborative in approach and adaptive.