Does predation risk affect spatial use in an introduced ungulate species? The case of a Mediterranean mouflon alpine colony

Predation risk is known to affect the spatial use of prey species, imposing a trade-off between feeding requirements and predation avoidance. As a result, prey species can leave high-quality forage areas to use sub-optimal, but safer, habitat patches, defined as “refuge areas.” In this study, we describe changes in the spatial use of an introduced ungulate species, the Mediterranean mouflon Ovis aries musimon, following the recolonization (in 1996) of wolves Canis lupus into the Albergian Hunting Estate (Italian Western Alps). Since 1988, we monitored the mouflon population by spring counts from vantage points. We georeferenced all observations and recorded the size and structure of the spotted groups. Finally, we identified available refuges by selecting patches characterized by (i) the presence of rocks and (ii) high values of steepness and ruggedness. We found that mouflons significantly reduced the average distance from refuge areas over the years, with the yearly average distance from refuges being 56% lower after wolves recolonized the area (i.e., 93.8 ± 32.1 vs. 213.1 ± 40.9 m). The analysis of orographic parameters showed that mouflons used patches with higher values in elevation, slope, ruggedness, and a significant difference in all three parameters when comparing years pre and post wolf return. Both sexes were significantly affected, but ewes were particularly sensitive and selected patches closer to refuge areas (75.8 ± 30.3 m) than males (131.0 ± 53.6 m). Our results suggest that the presence of new predators can alter the distribution of an introduced species such as the Mediterranean mouflon, triggering the resurgence of anti-predation behavior.