Elusive encounters: Activity patterns of the threatened Western polecat and niche overlap with co-occurring carnivores

Abstract

Understanding the temporal dynamics of carnivore assemblages is crucial for clarifying mechanisms of coexistence and co-occurrence and informing conservation planning. The Western polecat Mustela putorius, a medium-sized mustelid of conservation concern, remains poorly studied in terms of activity rhythms, particularly in southern Europe, where its populations are fragmented and declining. In this study, we investigated the temporal activity patterns and spatiotemporal relationships of polecats, assessing whether co-occurrence with other meso-carnivores may shape the species behaviour. Using systematic camera trapping across 35 stations in the northern Apennines in 2024–2025, we obtained 357 independent detections of medium-sized mustelids, including 41 polecats, 127 pine martens, 91 stone martens, and 98 unidentified Martes spp. Activity analyses confirmed significant deviations from random distributions for all species. Polecats and stone martens were predominantly nocturnal, with peak activity in the early night hours, whereas pine martens exhibited greater diurnal patterns, peaking in early morning. Overlap analyses revealed a high temporal overlap between polecats and stone martens, moderate overlap between polecats and pine martens, and intermediate overlap between the two marten species. Polecat activity was strongly influenced by lunar brightness, being concentrated in the darkest nights, whereas martens showed no significant response to moon phases. The Pianka index suggested also limited spatial overlap amongst all species pairs. These results suggest that co-occurrence among the three meso-carnivores at the landscape level may be facilitated primarily by spatial and habitat segregation, with temporal adjustments further reducing direct competition. The occurrence of polecat records mostly on camera traps located around aquatic habitats may explain their rarity in Italian camera-trap datasets and underscores their vulnerability to ongoing wetland loss. Species-level resolution (e.g., distinguishing between the beech marten and the pine marten) is essential to identify habitat segregation as the primary “coexistence” mechanism among mustelids, highlighting the need for species-specific analyses in carnivore community studies, given their markedly different ecological strategies despite phenotypic similarities.