Long-term climate associations with population decline in the Caspian Snowcock (Tetraogallus caspius) of northern Iran

Across the Palearctic, high‑elevation Galliformes are increasingly viewed as climate‑sensitive, yet multi‑decadal evidence of population trends remains exceptionally rare. We analyzed 27 years (1997–2023) of systematic ranger‑based monitoring (>3,000 patrol days) from the Alborz Mountains, Iran, to assess population trends in the Caspian Snowcock ( Tetraogallus caspius ). Its Relative Abundance Index (RAI) declined by 89.8% over the study period, decreasing from a mean of 2.1 ± 0.9 in the first decade (1997–2006) to 0.2 ± 0.2 in the most recent decade (2014–2023). Winter (driest season) mean humidity showed a strong positive association with RAI, whereas higher summer (warmest season) temperatures and greater maximum snow depth were negatively associated with RAI. Among these predictors, winter humidity declined significantly and summer temperature increased significantly over the study period, while maximum snow depth showed no significant long-term trend. Notably, the observed decline in Caspian Snowcock RAI occurred within the Golestanak core zone, a suitable habitat for the species and a strictly protected area with minimal human disturbance, suggesting an association between the population decline and climatic variation. Given the congruence of this decline, projected future habitat loss, and the suggested climate sensitivity, we argue that the current Least Concern (LC) status may warrant reassessment, at least not at the national level. Moreover, our findings carry an urgent warning: static protected areas, even when well enforced, are unlikely to safeguard high‑elevation birds under accelerating climate change without adaptive, forward‑looking management and landscape-scale conservation efforts.