Climate change impacts on altitudinal movements of society large mammals in the Alborz.

This study examines the impact of climate change on the altitudinal movement patterns and number of individuals of four large mammal species within the Central Alborz Protected Area (CAPA) region of the Alborz Mountains, a biodiversity hotspot, over a 23-year period (1999 to 2022). During the warm season (May 25-September 29), temperatures were reported to have increased by 2-2.5 °C, while relative humidity was observed to have decreased by 4-4.5%. Compared to the past two decades (2000-2022), Caspian red deer were observed to initiate their annual high-altitude migrations 15-20 days earlier, with the number of individuals in the summer range increasing more than threefold. Wild goats also migrated earlier, with peak arrivals increasing from 20-36 (1999-2003) to 36-57 (2018-2022) between May 25 and May 31, highlighting temperature as the primary driver of herbivore movement. In contrast, brown bears exhibited more subtle altitudinal movement, likely influenced by both temperature and humidity. Wild boars, with an approximate 40% increase in the number of individuals, tended to return to lower elevations earlier than in previous years (1999-2003). These patterns highlight the role of climate as a significant regulator of movement ecology, influencing high-altitude habitat use. However, human-induced barriers, such as roads and settlements, present additional threats to these seasonal migrations. This underscores the urgent need for adaptive management strategies, including the protection of movement corridors, the expansion of core zones, and enhanced community engagement, to support the resilience of these species under changing climatic conditions.