Sheep predominate the Early Neolithic faunal assemblages in the Iberian Peninsula. Their exploitation for meat and milk production made them key to the economy of these early farming societies. Management of sheep breeding season and feeding in the context of the local environment were decisive in obtaining these livestock products. This work focuses on these aspects through stable isotope and dental microwear analyses on sheep teeth from the cave of Chaves (Huesca, Spain). The results show the existence of “out of season” (autumn/early winter) sheep births in the Early Neolithic, contrasting significantly with spring lambing prevailing in Neolithic husbandries elsewhere in Europe and confirming the antiquity of a western Mediterranean characteristic in this regard. Furthermore, little changes in sheep diet throughout the year have been documented, as far as could be evidenced from stable carbon isotope ratios and dental microwear. Only two individuals showed higher variability in diet on a seasonal scale with possible contribution of C₄ plants, possibly from grazing in the valley steppes at lower altitudes. Overall the results suggest good adaptation of sheep to the Pyrenean mid-altitude environment and strong zootechnical knowledge of the earliest shepherds in this area.