Differential effects of environmental predictability on ungulate movement behavior in disparate ecosystems

Abstract

Increasing ecological perturbations resulting from global change processes are altering the environmental predictability (EP) of critical forage and water resources for wildlife. While research has furthered our understanding of how EP both underlies and directs animal movement, studies have mainly focused on relationships between EP and large-scale movement behaviors (e.g. migration) at the species level, neglecting the mediating influence that environmental context has on the behavior of wide-ranging species. We address these knowledge gaps by examining how EP of forage in mule deer Odocoileus hemionus - a cosmopolitan species of the American southwest - seasonal home ranges relates to average daily movement distance, focusing on two female populations inhabiting disparate ecoregions in Utah, USA (n = 225, 2015-2022). We employed two separate metrics of EP, representing spatial and temporal constancy of vegetation productivity, and explored how home range (HR) area, forage availability, and season modulate the relationships between EP and daily movement distance. We found spatial constancy of an individual’s HR significantly impacted movement during the summer and had significant interactions with HR area and forage availability. Interestingly, individuals inhabiting spatially constant HRs moved more in resource-limited seasonal environments, and less in non-limiting environments. Temporal constancy was a significant predictor of movement in non-limiting seasonal environments, resulting in shorter daily movements of deer with temporally constant HR areas. Finally, we found a significant interaction between spatial and temporal constancy, resulting in shorter daily movements of individuals inhabiting resource-limited HRs that were spatially and temporally constant. Interactions between HR area, forage availability, and constancy metrics demonstrate how the EP may become a larger driver of movement decisions as habitat quality is reduced. Understanding how EP drives movement of mule deer aids our ability to predict how global change will impact individual fitness, space use requirements and population demographics of ungulates.

Citation

Standen, Madeline P.; Ditmer, Mark A.; Stoner, David C.; Hersey, Kent R.; Carter, Neil H. 2025. Differential effects of environmental predictability on ungulate movement behavior in disparate ecosystems. Wildlife Biology. 2025: e01484.