Assessing the least effort path in animal movement

Efficient movement across landscapes is a key aspect of animal behavior, particularly in ungulates navigating rugged terrain. This study examines whether wild ungulates select movement paths that minimize energy expenditure, emphasizing the role of three-dimensional (3D) topographic factors over traditional two-dimensional (2D) models. Using graphical trace analysis over high-resolution aerial imagery, we digitized natural animal trails and compared them to randomly generated paths and least-effort algorithmic routes. We analyzed energy costs associated with different movement strategies in a rugged Mediterranean landscape. Our findings indicate that animal-selected paths generally follow less steep terrain, supporting the hypothesis that elevation differences significantly influence movement costs. However, while animals prioritize energy-efficient routes, they do not always align with least-elevation pathways generated by optimization models, suggesting additional ecological and behavioral factors in route selection. Statistical modeling, including mixed-effects models, confirmed the significant impact of topographic variables on locomotion costs. These results underscore the importance of integrating 3D energy cost assessments in movement ecology studies and have practical applications in wildlife management, sustainable grazing, and conservation planning. • Topographical factors affect animal mobility. • Wild ungulates select movement paths that minimize energy expenditure. • Statistical modeling confirmed the significant impact of topographic variables on locomotion costs. • These results underscore the importance of integrating 3D energy cost assessments in movement ecology studies.