Hotter days, smaller ranges: Air temperature constrains livestock movement and space use in Mediterranean rangelands

Abstract

Livestock has become the dominant large herbivore guild in most rangelands worldwide. Current climate adaptation frameworks emphasize extreme climatic events, although the extent to which these episodic drivers capture the environmental conditions shaping animal behaviour remains unclear. Rising temperatures and more frequent extreme climatic events (ECEs) are expected to influence animal behaviour, but the relative importance of daily climatic conditions versus discrete extreme events remains poorly quantified in managed grazing systems. Movement responses are especially informative as early-warning indicators of behavioural adjustments to environmental stress. We analysed GPS data from 26 sheep herds monitored in southern Spain between 2021 and 2022 (∼12,000 animals; 6464 monitoring days). Daily distance travelled, core area (50% kernel), and home range (95% kernel) were modelled against daily maximum air temperature, precipitation, pasture productivity (NDVI), distance to water sources, and the heat-wave indicator. Herds travelled shorter daily distances and used smaller core areas and home ranges as daily maximum air temperature increased, particularly during mid-summer. Across the annual cycle, all three responses showed nonlinear relationships with temperature, peaking at intermediate values, and were negatively related to NDVI. In contrast, precipitation and the heat-wave indicator were not retained in the best-supported models. Overall, daily maximum air temperature was consistently associated with all three movement and space-use metrics, whereas the heat-wave indicator was not retained in the best-supported models. As warming progresses, these contractions may reduce livestock movement, with potential consequences for vegetation dynamics and biodiversity. Anticipating such behavioural responses may help inform monitoring and management of Mediterranean grazing systems.