Livestock feeding strategies through the seasons: Isotopic evidence from the Late Iron Age site of Mas Castellar de Pontós (Girona, Catalonia)

• Sequential δ 13 C and δ 18 O analyses of dental enamel provided evidence of cattle feeding habits from Mas Castellar de Pontós. • Data confirm the integration of C 4 plants into the cattle diet during the warmer months. • Two possible options are proposed: the consumption of cultivated cereals or of wild plants from the coast and salt marshes. • Cattle, as well as sheep, had access to a diversified range of plant resources during the year. • The results suggest the adoption of a deliberate and adaptive seasonal livestock feeding strategy. This study investigates cattle feeding strategies at the Late Iron Age rural establishment of Mas Castellar de Pontós (Empordà plain, northeastern Iberian Peninsula), a key agricultural and commercial centre linked to the coastal Greek colonies of Emporion and Rhode. Previous isotopic data from bulk collagen analyses of bones (Messana et al. 2025) suggested a potential introduction of C 4 plants into the cattle diet; however, the temporal dimensions of this practice remained unclear. To address this gap, sequential analyses of δ 13 C and δ 18 O values were performed on dental enamel from seven lower molars belonging to five cattle, allowing a seasonal resolution of their feeding habits. The results confirm the seasonal integration of C 4 plants into the cattle diet during the warmer months, complementing a basal C 3 plant consumption during the year. Considering the landscape surrounding the settlement and the agricultural activity, two options are proposed regarding the nature of the C 4 plants consumed: cultivated cereals such as millet or wild plants growing along the coast and in salt marshes. The isotopic data currently available do not allow a discernment between the two hypotheses, resulting in a scenario of so-called equifinality. This pattern reflects a deliberate and seasonally adaptive feeding strategy, comparable to that observed in sheep from the same settlement. This evidence suggest that cattle, as has been documented for sheep, had access to a diversified range of plant resources during the year. These livestock feeding habits may have been adopted by herders to maximise the availability of pasture and/or fodder.