Space-use and social organization in a gregarious ungulate: testing the conspecific attraction and resource dispersion

• Authors:
  • Mélissa Peignier
  • Quinn M.R. Webber
  • Erin Koen
  • Michel P. Laforge
  • Alec L. Robitaille
  • Eric Vander Wal

This repository contains the code accompanying the paper “Space-use and social organization in a gregarious ungulate: testing the conspecific attraction and resource dispersion”. Scripts are under scripts/ and reused functions are in R/. This project uses standard R package structure and can therefore be installed with devtools. This also helps declare external package dependencies required for the analysis. Please note that while functions are included here, they are not tested for use in other projects and may not be suitable (at least not in their current version).

Abstract

Animals use a variety of proximate cues to assess habitat quality when resources vary spatiotemporally. Two non-mutually exclusive strategies to assess habitat quality involve either direct assessment of landscape features or observation of social cues from conspecifics as a form of information transfer about forage resources. The conspecific attraction hypothesis proposes that individual space-use is dependent on the distribution of conspecifics rather than the location of resource patches, whereas the resource dispersion hypothesis proposes that individual space-use and social association are driven by the abundance and distribution of resources. We tested the conspecific attraction and the resource dispersion hypotheses as two non-mutually exclusive hypotheses explaining social association and of adult female caribou (Rangifer tarandus). We used location data from GPS collars to estimate inter-annual site fidelity and networks representing home range overlap and social associations among individual caribou. We found that home range overlap and social associations were correlated with resource distribution in summer and conspecific attraction in winter. In summer, when resources were distributed relatively homogeneously, inter-annual site fidelity was high and home range overlap and social associations were low. Conversely, in winter when resources were distributed relatively heterogeneously, inter-annual site fidelity was low and home range overlap and social associations were high. As access to resources changes across seasons, caribou appear to alter social behavior and space-use. In summer, caribou may use cues associated with the distribution of forage, and in winter caribou may use cues from conspecifics to access forage. Our results have broad implications for our understanding of caribou socioecology, suggesting that caribou use season-specific strategies to locate forage. Caribou populations continue to decline globally, and our finding that conspecific attraction is likely related to access to forage suggests that further fragmentation of caribou habitat could limit social association among caribou, particularly in winter when access to resources may be limited.