Long-term climatic variables effects on reproductive phenology of wild mouflon in the Zagros mountains

• Long-term study links climate warming to earlier mating and calving in wild sheep ( Ovis orientalis ). • Autumn warming advances mating by ∼0.8 days per °C. • Winter–spring warming advances calving by ∼1.4 days per °C. • Phenological shifts vary spatially across Zagros mountain habitats. • Findings guide conservation strategies for vulnerable montane ungulates. Climate change poses a critical global threat, reshaping biodiversity through alterations in species’ morphology, behavior, and distribution. Among the earliest and most sensitive biological responses are shifts in reproductive phenology, which have profound implications for species survival and ecosystem function. Large mammals such as mouflon ( Ovis gmelini) are particularly vulnerable due to their ecological importance and limited adaptive capacity, and in Iran's climate-sensitive Zagros Mountains, these populations face additional pressures from habitat loss and poaching, while long-term ecological insights remain scarce. Leveraging over two decades of reproductive and meteorological data from five core habitats, this study quantifies climate-driven shifts in mating and lambing timing using generalized linear mixed models, which identified temperature as the dominant driver. Specifically, a 1 °C increase from May to November advanced mating by ∼0.8 days, and a 1 °C rise during December–April advanced lambing by ∼1.4 days, with spatial variation evident between the warmest site, Ghamishloo, and the coolest site, Tange Sayad. These findings demonstrate the pronounced sensitivity of Zagros mouflon reproductive cycles to temperature, highlighting reproductive phenology as a robust bioindicator of environmental change. Although no significant overall temporal shifts were detected across the Zagros region, local warming corresponded with measurable shifts in mating timing, reflecting spatial heterogeneity in climate effects. This work bridges critical knowledge gaps in ungulate ecology and provides quantitative evidence to inform conservation strategies for safeguarding biodiversity in Iran’s montane ecosystems under ongoing climate change.