THE STABLE ISOTOPE PALEOECOLOGY OF PLEISTOCENE WOLVES FROM THE INTERIOR OF EASTERN BERINGIA

Understanding the ecologic tolerances of modern, human-impacted carnivore populations is particularly important due to projected environmental change. Populations that are already fragile as a result of factors such as habitat constriction may be at risk of population degradation, or even extinction. Paleontological records store a wealth of information which we can use to interpret past patterns of how carnivore ecology has shifted in response to environmental change. Two such recent periods of rapid climate change are the Last Glacial Maximum (late Pleistocene, 25–15 ka BP) and the end of glacial conditions at the beginning of the Holocene (10 ka). Here we assemble data on the stable isotope biogeochemistry of late Pleistocene grey wolf bones that have also been AMS ¹⁴C dated, in order to more fully understand the ecology of wolves through time.

We analyzed the ¹³C/¹²C and ¹⁵N/¹⁴N ratios of collagen from fossil wolf bones collected from the Fairbanks area of Alaska. Since carbon and nitrogen in collagen are supplied by an animal's diet, they can serve as a proxy for diet and allow us to reconstruct predator (wolf) - prey links. Existing results for Beringian herbivores has found that patterns of covariation in plant isotope values allows for the discrimination between many of the dominant species (i.e. horse, bison, caribou, muskoxen) during the late Pleistocene. We refer to these herbivore data in order to reconstruct the diet of the Beringian wolves. The δ¹³C values of the wolves are relatively constant through time, but the δ¹⁵N values are more temporally variable. In general, the wolves from the full-glacial (~20 ka BP) have high δ¹⁵N values relative to wolves from the late-glacial (18-15 ka BP). The δ¹⁵N values of pre-glacial wolves are variable, and do not exhibit a pattern through time (45-25 ka BP). Shifts in δ¹⁵N may reflect a change in prey selection that was dictated by variations in both the abundances of different herbivores (prey) and carnivores (competitors) through time. An alternative cause for changes in wolf nitrogen isotope values is climatically (precipitation and temperature) mediated shifts in the δ¹⁵N values of primary production.