Shed female caribou antler on the Arctic National Wildlife Refuge

In the Arctic National Wildlife Refuge, AK (ANWR), the Porcupine Caribou Herd faces challenges to their calving grounds due to climate change and potential petroleum development. Available survey data show high variability in the yearly geographic distributions of calving grounds, which complicates efforts to (1) predict how calving grounds may change due to climate change and (2) establish the implications of proposed petroleum development on future calving success.

Unique aspects of caribou biology and ecology enable bone accumulations to significantly extend the observational window with which we study calving ground geography and intensity. Female caribou grow antlers, which are shed within days of calving. Because females congregate during calving (the entire herd is currently around 200,000 individuals), they produce large concentrations of shed antlers as well as the bones of newborns that do not survive. Funded by U.S. Fish & Wildlife Service and the National Geographic Society, my work has shown that these two skeletal signals correctly identify calving grounds in ANWR (Miller et al. 2013). This work follows previous research showing that concentrations of shed elk antlers in Yellowstone provide high quality data on winter landscape use (Miller 2012) and that accumulations of bones on landscapes provide rich historical datasets on local species composition and historical fluctuations in relative abundance patterns (Miller 2011, Behrensmeyer and Miller 2012). A comprehensive radiocarbon dating effort of antlers is currently processing. Data are revealing that antlers survive from hundreds to thousands of years, providing a significant temporal expansion of available ecological data. The data available from antler surveys are changing how we understand calving geography and their climatic drivers.

Every year, I return to the coast of the Arctic Ocean to survey antlers on the landscape and develop our understanding of this important landscape and the animals it supports.

Caribou skull on the tundra of the Arctic National Wildlife Refuge (ANWR) found during a standardized bone survey.