Friction based social force model for social foraging of sheep flock

Social foraging of large herbivores shows collective behaviors of movement and grazing. Conspecific effects and interactions between individual and food distribution are known as important factors to influence foraging behaviors of sheep. Many rules of movement have been designed largely depending on conspecific effects. However, few simulation methods consider individual interactions with food distribution. In this paper, we first introduce instinct of feeding to represent individual interaction with currently located patch and then propose a novel friction based social force model to simulate different behaviors in social foraging. Friction force quantifies individual instinct of feeding on currently located patch since conspecific effects and attractions of food in other patches are external forces causing positional adjustment. In our model, agent decides to move if external forces are larger than current friction force and the destination patch can provide enough friction force to resist external forces. This result shows variable effects of instinct of feeding on social foraging and exhibits typical tortuous migration paths and departure-following collective movement of sheep flock. Our model emphasizes the importance of individual interactions with food distribution and may provide new insights into the mechanism governing internal decision process.