Guest or pest? Spatio-temporal occurrence and effects on soil and vegetation of the wild boar on the Elba island

In areas where allochthonous large mammals, such as the wild boars (Sus scrofa), occur in high density, human-wildlife conflicts may arise. In these contexts, assessing spatio-temporal patterns of the introduced population is paramount to its management. Here, we studied wild boars in the Elba island, Italy, where they have been introduced and are perceived as pests. While crop-raiding has been documented, no studies addressed the spatio-temporal occurrence, nor the impact of foraging on natural habitat. We surveyed the Western part of the island with three camera trapping surveys within one year. We found that the species' estimated occupancy probability was higher in summer-autumn (0.75±0.14) and winter-early spring (0.70±0.10) than in late spring-summer (0.53±0.15), whereas detection probability did not vary. Occupancy was significantly associated with elevation and vegetation cover, with preference for lower elevation and woodland. The lower site use of wild boars during spring-summer might reflect lower food availability in this season, and/or movements towards landfarms outside the sampled area. Detectability increased with proximity to roads during spring-summer and decreased with humans' relative abundance in the other periods. Moreover, boars were mainly nocturnal, with an overlap with human activity that decreased when human presence was higher. Combined, these suggest behavioural avoidance of human disturbance by boars. We also evaluated the impact of boars' foraging on the soil and vegetation and found that it was higher in pine plantations than other covers, however, it was not associated with variation in boars' occupancy across habitats. Our results indicate that the spatio-temporal activity of wild boars on Elba island appears driven by seasonal preferences for food-rich cover and avoidance of human disturbance. The lowered site use in months with lower resources could partially reflect increased proximity to settled and farmed areas, which may, in turn, trigger crop-raiding and hence the negative perception by residents

Spatiotemporal activity of the pine marten Martes martes: Insights from an island population

Behavioral interference and interspecific competition shape the spatiotemporal behavior of carnivores, where intra-guild predation has been recorded as a strategy to limit competition. Very often, disentangling the effect of intra-guild effects from other ecological processes is challenging, if not impossible. This work aimed to assess the spatiotemporal behavior of the pine marten Martes martes in an island ecosystem without any intra-guild predation. Using an intensive camera-trap survey on Elba Island, Italy, we estimated occupancy, detection probability, and locomotor rhythms of the species. The pine marten occurred throughout the study area, showing a tendency to avoid urban areas during the high tourist season. Occupancy was higher in colder months and lowered in autumn, following opposite fluctuations of recorded human presence. Conversely, the detection probability remained low throughout the year, confirming the pine marten elusiveness. With other studies conducted in sympatry with other carnivores or predators, Elba Island martens showed locomotor ground activity mostly at dawn and dusk throughout the year, with an increasing diurnal locomotor activity in spring, when cubs are present. The spatiotemporal behavior of the pine marten in Elba island did show little variation across seasons. It was similar to those reported where potential predators were present, suggesting the intra-guild predation not playing a significant role in shaping the spatiotemporal activity of pine martens