Identifying Seasonal Patterns of Site Use at a Sahelian Archaeological Site in Yobe State Using Stable Oxygen Isotopes

Seasonality of site occupation is a critical but often elusive dimension of mobile and semi-mobile communities in Sahelian environments, where the alternation of wet and dry seasons structures both ecological productivity and human mobility. This study investigates seasonal patterns of site use at an archaeological site in Yobe State through stable oxygen isotope analysis of animal tooth enamel, exploiting the ontogenetic variation in isotopic composition that records the seasonal precipitation signal during dental development. Samples were drawn from an assemblage of bovid and caprine teeth recovered from a stratified deposit spanning approximately five hundred years, with a minimum of three individuals per stratigraphic phase selected to enable intra-site diachronic comparison. The sinusoidal isotopic profiles reconstructed from serial sampling of complete tooth crowns indicate that both cattle and goat were present at the site predominantly during the dry season, with isotopic profiles approaching the expected wet-season minimum not present in most specimens. This pattern is interpreted as evidence for a seasonal aggregation site used by pastoralists during the dry season, when permanent water sources in the area concentrate both herds and herding communities. Diachronic comparison shows no significant change in this seasonal pattern across the five-hundred-year sequence, suggesting stable seasonal land use strategies over the study period. The study contributes to the emerging literature on Sahelian pastoral archaeology and advocates for oxygen isotope seasonality studies as a standard component of assemblage analysis at northern Nigerian sites. Keywords: stable oxygen isotopes, seasonality, Sahelian archaeology, Yobe State, pastoral site use.