Social copying drives spatial allocation in gregarious herbivores

Abstract

Resting patch selection in free-ranging social cattle (Bos taurus) inhabiting steep, rugged, mountain valleys is critical, because the recurrent use of flatter resting patches may reduce energetic costs and enhance fitness prospects. As these patches may constitute a limited resource, understanding their pattern of use dynamics may help explain resting patch selection. We therefore combine empirical data with a theoretical modelling framework to investigate the processes underlying resting patch selection. Using high-resolution GPS tracking data from 144 cows collected over three seasons, we identify several recurrently used resting patches located on significantly gentler slopes than expected in the valley. We then build a simple, memory-free agent-based model, which suggests that the dynamics of resting patch selection arise from social copying and, to a lesser extent, from individual heterogeneity. The model quantitatively reproduces three empirical observables: a slowing (sub-linear) discovery of new sites through time, heterogeneous occupancy across resting patches and similarity in patch use among individuals. These results suggest that collective dynamics in social species can emerge primarily from a simple social mechanism with weaker modulation from inter-individual heterogeneity, such as age, without explicitly incorporating individual memory to reproduce the aggregate patterns.