Reconstructing caribou seasonal biogeography in Little Ice Age (late Holocene) Western Alaska using intra-tooth strontium and oxygen isotope analysis

The palaeobiogeography of key prey-species can provide valuable insights into animal-human interactions, human subsistence activities and landscape use in the past. In many contemporary indigenous Arctic societies, caribou (Rangifer tarandus spp.) are an important seasonal subsistence species, and recent climatic shifts have influenced the seasonal and spatial distribution and migrations of herds. The impact of larger scale climatic change on this species, such as that experienced during the Little Ice Age (LIA), is not known, but may provide vital clues about future variability. Here we present sequential strontium (Sr-87/Sr-86) and oxygen (delta O-18(CO3)) isotope data from archaeological caribou tooth enamel from Nunalleq, a 15th to 17th century AD pre-contact Yup'ik village site in Western Alaska, to reconstruct caribou movement patterns in this region during the LIA. The results of these analyses highlight variation in ranging habits over the period of time that the site was occupied, and indicate different ranging behaviours in the region in the past compared to modern herds in the area today. The isotopic data presented here complement the wealth of data derived from other research at Nunalleq, illuminating the influence of changing climatic conditions on prey-species palaeoecology and humananimal interactions at the site.