Microhabitat features shape small mammal urban assemblages across Italian cities

Urban ecosystems, often perceived as biodiversity deserts, can support diverse wildlife, particularly within well-structured green spaces. In our work, we investigated the influence of microhabitat features on native non-synanthropic small mammal communities in three Italian cities. Using 1 × 1 km grid cells across varying green space sizes and fragmentation levels, we recorded ten native species. Species richness varied significantly among cities and habitats. Main factors influencing diversity included tree and shrub cover, herbaceous layer height, and the presence of water bodies. Higher cover of native broadleaf trees and diverse shrub layers positively correlated with species richness. A moderate herbaceous layer height provided optimal foraging and shelter sites. Proximity to water sources significantly increased species richness and abundance. Green spaces connected to larger natural areas supported high diversity. Small mammals were significantly influenced by habitat characteristics and indicating specific sets of environmental conditions, with sensitive species like M. avellanarius and Sciurus vulgaris reflecting higher ecological integrity through their presence. Conversely, simplified small mammal communities or the absence of habitat specialists signalled ecological degradation. Our findings showed the value of integrating microhabitat enhancements into urban planning to support biodiversity. Specifically, maintaining and restoring native vegetation with diverse structural layers, reducing fragmentation through ecological corridors, and minimizing human disturbances such as mowing and pesticide use are vital. By improving habitat heterogeneity and connectivity, cities can sustain resilient small mammal populations and promote overall urban ecological health.