Landscape opening and herding strategies: Carbon isotope analyses of herbivore bone collagen from the Neolithic and Bronze Age lakeshore site of Zurich-Mozartstrasse, Switzerland

Carbon isotope analysis (d13C) was performed on collagen extracted from 54 domestic cattle (Bos taurus) and 20 red deer (Cervus elaphus) bones from the Neolithic (3913-2586 BC) and Bronze Age (1950-950 cal. BC) layers of the lakeshore site Zurich-Mozartstrasse located in the lower Lake Zurich basin, Switzerland. We observed shifts in the d13C of both domestic cattle and red deer over two millennia. Mean d13C values of red deer changed from 24.1 ± 0.7‰ to 22.5 ± 0.3‰, while mean d13C values of domestic cattle showed minor changes from 22.7 ± 1.3‰ to 22.1 ± 0.3‰. Our data suggest that in the early 4th millennium BC the landscape was densely forested with red deer feeding in closed habitats and cattle grazing in more open landscapes. Forest was also a food resource for some young cattle as indicated by the lower d13C values of non-adult relative to adult animals. This points to a greater diversity of herding strategies and feeding techniques compared to the later periods. The landscape was still rather forested towards the mid-3rd millennium BC, with no obvious changes in the habitat use of the large herbivores. However, the carbon isotopes suggest a clearly reduced forest cover in the 2nd millennium BC with red deer using similar open feeding grounds as domestic cattle. Our study demonstrates that the stable carbon isotope composition of archeological bone material from large herbivores can provide integrative constraints on paleoenvironmental and vegetation changes, prehistoric animal management and land-use.