Up the mountain and back again: sequential stable isotope analysis reveals altitudinal migration in wild sheep (Ovis cf. orientalis) from the PPNA site of Nachcharini Cave, Lebanon

The Pre-Pottery Neolithic A (PPNA) marks an early phase in the transition from foraging to farming in Southwest Asia. Although this stage of neolithization shows evidence of early plant cultivation, subsistence strategies remained primarily dependent on hunting. While faunal data from the northern and southern Levant reflect regional differences in prey choice and hunting strategies, patterns in the central Levant are less well defined. In this study, we use stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotope values measured sequentially in the tooth enamel of wild sheep (Ovis cf. orientalis) from the PPNA site of Nachcharini Cave in northeastern Lebanon to reconstruct seasonal mobility and ecology in this prey species. The isotopic sequences show negative covariation between δ¹³C and δ¹⁸O values, consistent with seasonal altitudinal migration between alpine C₃-dominant summer ranges and lower-elevation wintering grounds with mixed C₃/C₄ vegetation. This mobility pattern suggests that sheep occupied the alpine zone only seasonally, requiring PPNA hunters to possess detailed ecological knowledge to target them during their highland presence. The broadly consistent placement of δ¹⁸O maxima suggests births clustered within a specific season, likely timed to align with forage availability and the physiological demands of migration, as seen in modern montane wild sheep. Low inter-individual δ¹⁸O variation supports relatively short-term faunal accumulation, while higher δ¹³C variation reflects dietary and environmental heterogeneity. These results reinforce the interpretation of Nachcharini Cave as a seasonal alpine hunting camp and highlight the role of logistical mobility and ecological knowledge in structuring PPNA subsistence practices in the central Levant.