Doctor of Philosophy
Lisa M. Hodgetts
Fred J. Longstaffe
This dissertation explores the ecology of caribou (Rangifer tarandus spp.) and muskoxen (Ovibos moschatus), and its relevance to human hunters on Banks Island, NWT, Canada, over the last 4000 years, primarily through the isotopic analysis of modern and archaeological faunal remains.
First, we establish baseline carbon and nitrogen isotope relationships between modern vegetation and caribou and muskox bone collagen using Bayesian mixing models. The models indicate that dwarf shrub (Salix arctica) does not contribute significantly to bone collagen isotopic compositions in either species, while sedges and yellow lichen (Cetraria tilesii) do. These findings are ecologically significant considering that shrub phytomass is expected to increase across the Circumpolar Arctic, while lichen phytomass is expected to decrease.
Second, we investigate the hypothesis that niche competition caused periodic declines in the caribou and muskox populations over the last 4000 years, using archaeological bone collagen δ13C and δ15N. After accounting for the possibility of different trophic discrimination factors in both species, the isotopic data suggest that caribou and muskoxen typically occupy the same niche, but tend towards niche expansion during cold or climatically-unstable periods.
Third, we evaluate the potential of reconstructing seasonal movements and migrations in caribou and muskoxen by sequential measurements of tooth enamel δ18O on the micrometer-scale. We conclude that seasonal variation in precipitation δ18O obscures geographic variation in δ18O in these tooth enamel samples. The intra-tooth patterns in δ18O are useful as paleoenvironmental proxies as they reflect changes in seasonality across time.
Munizzi, Jordon S., "Rethinking Holocene Ecological Relationships Among Caribou, Muskoxen, and Human Hunters on Banks Island, NWT, Canada: A Stable Isotope Approach" (2017). Electronic Thesis and Dissertation Repository. 5089.