ON THE SPATIAL FIDELITY OF ARCTIC DEATH ASSEMBLAGES: CARIBOU CALVING GROUNDS AND THEIR SKELETAL INDICATORS

While death assemblages of many taxonomic groups show high ecological fidelity to their source communities, less work has tested the spatial fidelity of bone accumulations. Establishing the capacity of bone assemblages to capture geographic use, including the identification of regions and habitats with significant ecological value, may lead to the collection of new paleoecological data. Bone and antler accumulations of caribou (Rangifer) may provide particularly extensive ecological data because both males and females annually grow antlers, which are shed at gender-specific times and geographic areas; male antlers are shed after mating, while pregnant females shed their antlers after giving birth. Accumulations of caribou antlers can be common in Pleistocene assemblages, and it may be possible to extract data on season-of-accumulation and even geographic use from such remains. Using modern skull and antler collections (University of Alaska, Fairbanks) of caribou (R. tarandus) and bone surveys of known caribou calving grounds (Arctic National Wildlife Refuge, Alaska), this preliminary study tests (1) if genders of shed caribou antlers are morphologically distinguishable, and (2) if expansive arctic calving grounds produce high concentrations of shed female antlers and neonatal skeletal remains. Results show that caribou antlers can be differentiated by gender based on linear measurements of the pedicle surface (antler-skull connection) – the same surface used to distinguish shed antlers from mortality-derived antlers. Transects show known calving grounds host abundant shed female antlers (up to ~10³/km²), with vegetation-types most suitable for calving yielding significantly higher antler concentrations than poorer-quality habitat. Compared to other large-mammal death assemblages (Yellowstone National Park, WY), arctic calving grounds contain anomalously high ratios of neonatal:adult skeletal remains. Seasonally-specific skeletal contributions (i.e., shed antlers) are deposited in spatially and environmentally appropriate accumulations which may provide (a) added ecological insight into Pleistocene assemblages, and (b) a new tool for identifying critical regions and habitats for the management and conservation of poorly-understood caribou communities on modern landscapes.