The ups & downs of Iron Age animal management on the Oxfordshire Ridgeway, south-central England: A multi-isotope approach

The hillforts of the Oxfordshire Ridgeway in south-central England have been interpreted as central places in the Early/Middle Iron Age, ca. 600–100 BCE, serving, among other functions, to integrate the management of animals, particularly sheep, between the upland Chalk downs and the adjacent low-lying Vale of the White Horse. Since these landforms differ geologically and pedologically, they lead to distinct isotopic ratios in the biosphere and so present the potential to investigate animal management practices in some detail. Here, we report the results of a multi-isotope study on domestic fauna (cattle, sheep and pig) within a very constrained study area, with the aim of testing the hypothesis that the Ridgeway's hillforts were placed to control and coordinate the movement of sheep between the Chalk and the Vale. However, the results suggest a different scenario. Bone collagen δ ¹⁵N results indicate that cattle and sheep were both kept locally. Strontium isotopes, conversely, indicate that, while sheep and pigs were raised locally, cattle appear to have been mainly kept in the Vale during at least the first year of their lives. The apparent discrepancy between the two isotopes can be reconciled by the different periods of life represented by enamel and bone collagen measurements, with the movement of cattle onto the Ridgeway in their second or third year of life. Sequential measurements of δ ¹³C and δ ¹⁵N in dentine, and of δ ¹³C _c and δ ¹⁸O _c in enamel, provide further detail on the management of cattle, and offer some support for the above scenario. Early/Middle Iron Age stock-keeping in south-central England was complex, being integrated in some respects but distinct in others. The study demonstrates the level of detail it is possible to achieve with a multi-isotope approach to animal management practices in prehistory. The focus on a micro-region contrasts with, or rather complements, studies addressing larger-scale movement of animals in the past.