Archaeology Research

They Graze on Wave and Ocean Plants

Dr Ingrid Mainland and Dr Philippa Ascough, Lecturer & Head NERC Radiocarbon Facility (East Kilbride) talk about their research into foddering strategies in island environments: pig, sheep, goat and cattle diet in Late Iron Age to Viking/Late Norse Orkney.

Within the archaeological literature, the Northern Isles of Scotland are typically seen as being at the limits of arable and pastoral farming.In these islands, the use of foreshore grazing and of seaweed as fodder from the Neolithic period onwards is often equated with marginality, a farming system under pressure, with animals reduced to foraging on the shore to obtain an adequate diet. Yet, today and in the recent past, livestock farming has been one of the mainstays of the economy of the islands, with the fertile coastal soils of Orkney in particular providing ideal grazing for cattle and sheep. Using Late Iron Age (LIA) to Viking (V) and Late Norse (LN) Orkney as a case study, and integrating zooarchaeological approaches with bone stable isotope analysis (carbon, δ13C, & nitrogen,δ15N) we explored the idea of pastoral farming at the margins through an analysis of the differing herding, foddering and grazing strategies employed for domestic livestock at Norse farmsteads of different size and status across the islands.  This forms part of a larger study into the resilience of LIA to Norse herding strategies in Orkney.

Map of Orkney showing sites used in this study

The method employed  a synthesis of zooarchaeological data (species representation, mortality profiles, palaepathological and metrical data)  from 16 sites spanning the Late Iron Age to Late Norse period in Orkney & Shetland3. Bone stable isotope analysis sampled collagen from sheep/goat (n=62), cattle (n=59) and pig (n=41) mandibles from selected sites (in bold Fig 2.1) using standard analytical approaches.

Zooarchaeological Results

  • Sheep and cattle dominated economy in LIA and Viking
  • Increasing evidence of specialisation in Late Norse (eg sheep at Snusgar, pig at Earls’ Bu and Brough of Birsay, cattle at Quoygrew)
  • Sheep: mixed meat, wool and milk in LIA; specialised strategies in Late Norse – meat at Earl’s Bu and Brough of Birsay; wool at Snusgar
  • Cattle: milk important throughout, but increased emphasis on dairying in Late Norse

Change in Foddering Strategies

Grazing/foddering was more opportunistic in earlier periods, including seaweed grazing by ovicaprines. In the Late Norse period,  there is greater consistency between sites, with terrestrial grazing emphasized and the feeding of some pigs on marine waste.


A shift in strategy is identified from LIA to Late Norse in both husbandry and diet which is interpreted as a move from subsistence farming to a system geared towards the production of specific products.  Coastal grazing and/or seaweed consumption is identified but in relatively few individuals, and does not suggest an acute level of resource scarcity for livestock as described, eg, in historical accounts for the Northern Isles.  Moreover, there is evidence from the stable isotope results both in this study and others. 3,5 of the use of supplementary fodders, such as hay or oats, which suggests well husbanded flocks and may reflect the fattening-up of livestock for consumption.   Likewise preliminary analysis of dental microwear in some of the sites examined here shows little evidence for overgrazing in either summer or winter culled animals.3  Overall, the impression is of a productive and well managed farming system during the Viking/Late Norse period. Although sample sizes are small, there is some suggestion that utilisation of marine resources for sheep may have been greater in the LIA.  Jones  et al. (2012)5 also report enriched δ13C in bone collagen in a wider range of Iron Age sites from Orkney, suggesting a more widespread use of seaweed and foreshore grazing by sheep herds at this time though again some variability is evident in the extent to which this resource was utilised.

Poster presented at the UHI Conference & the AEA conference in Orkney in April 2016. The poster also details the stable isotope results:



  • Amorosi et al. 1996. Env Arch 1, 41-54;
  • Balasse et al. 2009. Env Arch 14.1, 1-14;
  • Mainland et al. 2016. JAS Reports 6, 837-855;
  • Ascough et al., 2012, J. Arch. Sci. 39, 2261-2271;
  • Jones et al. 2012. Rapid Commun. Mass Spectrom. 26, 2399–2406.
  • aUHI Archaeology Institute, University of the Highlands and Islands (
  • Scottish Universities Environmental Research Centre (

british-academyThis research was supported by a British Academy Mid-Career Fellowship to Ingrid Mainland (2014-5).