Effects of global changes on small and meso-predators

Small and meso-predators occupy a key yet understudied ecological position, integrating both bottom-up processes (prey dynamics, habitat structure) and top-down pressures (larger predators, human disturbance). This makes them particularly responsive to environmental change and effective indicators of ecological perturbations. Mountain ecosystems harbour exceptional biodiversity, including many species adapted to snowy conditions, but are increasingly exposed to global change. Climate warming, declining snow cover, land-use change, infrastructure development, and expanding outdoor recreation are reshaping species distributions and ecological interactions. Alpine ecosystems are relatively simple in structure, making them particularly sensitive to disruption while also providing suitable systems for investigating ecological responses to environmental change. Accordingly, small and mesopredators in alpine environments, although still poorly studied, represent promising sentinel species for global change. This thesis focuses on small and meso-predators in the Italian Alps, with particular attention to small mustelids, and investigates how global change influences their ecology, distribution, and conservation. Starting from a broad perspective on mountain ecosystems under environmental transformation, I progressively narrow the focus to speciesand process-level responses in mountain small carnivore communities. First, I address a fundamental methodological challenge: the reliable detection of elusive small carnivores in alpine environments. By comparing camera trap-based approaches, I demonstrate that a targeted enclosed system can substantially increase detection efficiency while reducing nontarget records, providing a robust foundation for long-term monitoring. Building upon this framework, I then examine habitat suitability and ecological niches of sympatric small mustelid species using spatially explicit modelling approaches. Through Ecological Niche Models, I identify the main environmental drivers shaping their distribution in northwestern Italy and assess patterns of niche overlap and differentiation across elevational and habitat gradients. These analyses clarify how climatic conditions, land cover, and landscape configuration contribute to structuring small mustelid assemblages in the Alps. I then examine the effects of human disturbance, particularly outdoor recreation and associated infrastructure, on the activity patterns of mountain small carnivores. Results indicate marked temporal shifts in activity patterns during periods of higher human disturbance, suggesting potential cascading effects on interspecific interactions and increased exposure to anthropogenic risks such as road mortality. 5 Finally, through Species Distribution Modelling, I assess how climate-driven environmental change may alter predator–prey dynamics. Projections indicate that snow loss and changes in prey availability could reduce habitat suitability for alpine stoats, potentially threatening their long-term persistence in several sectors of the Italian Alps. Overall, this thesis advances knowledge of small and meso-predators in a mountain region where empirical evidence has historically been scarce. By integrating methodological innovation, collaborative monitoring networks, and spatial modelling approaches, it provides the first coordinated assessment of how climate change, land-use transformation, and human disturbance jointly shape the distribution, behaviour, and persistence of small carnivores in the Italian Alps. These findings highlight species-specific vulnerabilities, ranging from the intrinsic challenges of detecting elusive mustelids to the reduction of snow cover affecting cold-adapted species, and the behavioural impacts of outdoor recreation, while identifying practical tools and priorities for long-term monitoring and conservation in rapidly changing alpine landscapes