An Uncomfortable Neighborhood: Presence Evolution of Two Competing Carnivores in North-Eastern Italy

Within ecological communities, larger predators typically limit mesocarnivore populations. On a continental scale, this may be the case for the gray wolf (Canis lupus) over the golden jackal (Canis aureus) in Europe. North-eastern Italy represents one of the first areas in Western Europe to experience golden jackal colonization, followed by wolf recolonization. Since few studies have investigated the spatial relationship between these two wild canids, this work aimed to analyze their distribution dynamics and investigate whether the wolf and environmental factors may have influenced golden jackal distribution. We used systematic and opportunistic data collected over 11 years (2013-2023) to assess the presence of both species on a 10 × 10 km square grid system. A multinomial logistic mixed model (MLMM) was applied to test whether the study period and landscape metrics (terrain ruggedness and habitat fragmentation indices) influenced both species' presence at a broad scale (i.e., square grid units). Generalized linear mixed models (GLMMs) were used to test whether the wolf and landscape metrics influenced jackal presence at a finer scale (i.e., jackal howling calling stations). Both species showed an increase in their former distribution, with a small growth in sympatric areas. Models revealed that jackals preferred less rugged and more fragmented areas typical of the lowland, whereas wolves preferred rugged terrain with extensive forested patches in the Alpine range. Furthermore, our results showed that, at a local scale, golden jackal presence was negatively related to wolf presence. This study provides further insights into the coexistence of these two competing wild canids, suggesting a potential top-down effect of the wolf on golden jackal colonization dynamics. However, the wolf influence may vary in intensity depending on environmental context, with a weaker effect in areas of higher human pressure, such as the lowlands.