Modelling wildlife-human relationships for social species with mixed-effects resource selection models.
Resource selection functions (RSF) have contributed to the conservation of species negatively affected by human activities. Despite these applications, two assumptions frequent many studies: the assumption of independence among groups in social species, and that selection is proportional to resource availability. This latter case is known as a functional response in resource selection, and may be especially important in human-wildlife relationships where there is a fitness cost of proximity to humans. Recent advances in generalized linear mixed models offer new ways to account for resource selection in social species and functional responses by accommodating correlations within hierarchical groups with random intercepts, and functional responses with random coefficients. We illustrate the application of mixed-effects RSF models using a case study of resource selection by individual wolves Canis lupus living in packs as a function of human activity. In areas of low human activity, wolf resource selection was independent of proximity to humans. As human activity increased, wolves displayed a functional response selecting areas closer to human activity. With increasing human activity, however, wolves displayed spatio-temporal avoidance of human activity during daylight. This could lead to behaviourally induced trophic cascades mediated by wolf avoidance of human activity, and fits within the framework of attractive sink habitats. Accounting for the hierarchical social structure of wolves clearly showed that the response of wolves to human disturbance was strongly correlated, but different, within packs, and that the correlation was strongest during winter and weakest during summer. Syntheses and applications. Failure to consider the social structure of wolves and the functional response to human activity would result in mistaken conclusions about wolf-human relationships. Our approach provides a unifying framework to understand the contradictory results of previous studies of wolf-human relationships and a template for future studies to evaluate effects of increasing human activity on wildlife.