ANTLERS OF THE ARCTIC NATIONAL WILDLIFE REFUGE: BASELINES OF BIOLOGICAL VARIABILITY FROM BONES ON THE TUNDRA (Invited Presentation)

Quantifying natural variability in geographic range (including seasonal landscape use and migration) is a primary concern for evaluating the status of modern animal populations and establishing management and conservation goals. For most populations, however, this variability is modeled using datasets with limited temporal perspectives. This predicament is exacerbated in arctic settings, where logistical complexities frequently interfere with biological surveys and further complicate available data; including on economically and culturally keystone species, such as caribou (Rangifer tarandus). Antlers of caribou accumulating on landscape surfaces have exceptional potential to provide historical data on seasonal landscape use because they are annually grown and shed by both males and females. Male antlers are shed post-mating, while pregnant females shed antlers in conjunction with giving birth. Thus, the geographic distributions of male and female antlers offer data on migration and calving areas (birthing grounds). Antlers can then survive on arctic landscapes for centuries or more. We use bone and antler surveys to quantify historical variability of landscape use and calving ground distributions in the Arctic National Wildlife Refuge (ANWR). We then evaluate recent landscape use (based on survey data initiated in the 1970s) against historical patterns. On the ANWR calving grounds, tens of thousands of caribou annually bare young within a limited duration and in concentrated areas. The resulting accumulations of shed female caribou antlers can be very large (> 1,000 antlers/km²). Furthermore, relative to expectations from aerial surveys, many regions have higher-than-expected pre-1970 antler inputs. Additionally, the rank-order correlation between modern calving activity and the pre-1970 antler record is low, indicating a lack of congruence between modern and historical calving patterns. Antler surveys have also revealed high concentrations of female antlers in regions that lack aerial survey or telemetry data, adding novel data on calving geography. Data from antler surveys, which also provide insight into the formational processes of fossil records, place recent calving patterns within historical contexts and offer new data with which to contribute to wildlife management.