The integrated role of resource memory and scent-mediated territoriality in the emergence of home-ranges

Meryl Theng, Steven Delean, Phill Cassey and Thomas A. A. Prowse, The University of Adelaide, Adelaide, Australia, Chloe Bracis, Université Grenoble Alpes, Grenoble, France

Background/Question/Methods
Despite decades of extensive animal movement research, we still lack an integrated, process-based understanding behind the movement decisions that individuals make, which ultimately lead to the emergence of home-ranges. Here, we advance toward a more holistic understanding of HR formation, by developing a theoretical model integrating two key processes that have been separately proposed to play important roles in HR formation in territorial animals: (i) optimising resource acquisition by referencing a cognitive memory (i.e., resource memory); and (ii) minimising resource competition through defensive cues (i.e., territoriality). We extend a two-state memory-based model for non-territorial animals to include multiple individuals that interact through scent-mediated conspecific avoidance behaviour. We investigated how the interplay of memory and territoriality influenced: (1) the emergence of individual home-ranges; (2) the relationship between home-range size, density and resource availability; and (3) the response of animal home ranges to perturbations of the conspecific environment (i.e., removing individuals). We then conducted a sensitivity analysis on the movement model to assess parameter importance for multiple metrics of movement and to guide the calibration of model parameters using data from telemetry data.

Results/Conclusions
We showed that integrating both resource memory and territoriality gave rise to spatially distinct and dynamic HRs that follow a negative log-linear relationship with respect to resource distribution (Pearson’s r = -0.73, p < 0.01), congruent with empirical evidence. On its own, neither process resulted in a similar response. The high importance (> 50%) of both resource memory and scent parameters on HR size and degree of HR overlap demonstrated how recreating stable HR patterns is ultimately a balance between an animal’s inherent exploratory tendency and its’ desire to avoid conspecifics. In model calibration, we could approximate general spatial measures (step-length, daily displacement distance, HR size) and patterns of space use in our empirical data, including the phenomenon of transience. While replication of finer-scale spatio-temporal space use patterns was challenging, we discuss how it is plausible with specific considerations for future investigations.