Movement of caribou across Arctic landscapes: The role of wildlands in sustaining animal migrations

Background/Question/Methods

Alaska’s four Arctic caribou migrate hundreds of miles annually, and pass through native, state and federal wildlands with different management objectives, little of which is permanently protected and less than 15% is designated Wilderness.  Due to the remoteness of this area, there has not been significant industrial development due to the lack of access and thus costs of development despite substantial oil, gas and mineral resources.  Should future conditions favor development, caribou could face habitat loss and fragmentation and increased hunting pressure, while also adapting to the the effects of climate change, such as loss of winter lichen forage with increased fire. We reviewed the literature, data from collared caribou and modeled disturbance scenarios to analyze caribou selection of migration corridors and seasonal habitat, factors regulating populations and response to disturbance to make recommendations on how to protect high-value habitat across migration routes. We present a map highlighting key vulnerabilities in caribou migration paths and seasonal ranges.

Results/Conclusions

Alaska’s Arctic caribou herds are relatively large, and despite population fluctuations, appear to be sustainable at present.  Each of the four herds, as well as individuals within a herd, shows considerable variation in migration distances and winter habitat selection, while summer habitat is more similar given the herds are defined by calving on the north slope of Alaska.  Caribou response to development can be observed where collared caribou encounter roads and infrastructure, but responses show differences in intensity across seasons and sexes, with calving season representing the most sensitive period for cows with calves.  Increased oil and gas development, new roads, mining and hunting access into caribou migration corridors could alter movement patterns as well as fitness and population viability.  Changes in vegetation associated with climate change are most likely to affect migration where vegetation grows taller, a habitat generally avoided during migration likely due to cover for predators.  Much of the habitat within the migratory ranges is not under permanent protection and conservation will require cooperation among primarily state and federal land managers.