Landscape composition and photoperiod shape differences in space use and hunting behaviour between boreal and Alpine pygmy owl populations

Abstract Context Investigating how habitat specialists express population-level differences in habitat preferences and movement behaviour across contrasting landscapes and abiotic environments allows us to distinguish patterns that are consistent across populations from those that are population-specific responses to local conditions. Objectives We examined space use, hunting habitat selection and diel activity between Eurasian Pygmy Owl ( Glaucidium passerinum ) populations occupying boreal (south-west Finland) and subalpine (Western Italian Alps) forests, to assess the consistency of these patterns across regions with contrasting landscape structure and photoperiod. Methods From 2021 to 2024, we GPS-tagged 26 breeding males (13 per region), obtaining 6076 GPS locations. We estimated 90% home-range areas using autocorrelated kernel density estimators (AKDE). Hunting habitat selection was examined with resource selection functions implemented as GLMMs, and diel activity was characterised by modelling activity probability with cyclic GAMs. Results Pygmy owls behaved as clear forest specialists in both regions: 90% AKDE home ranges were dominated by continuous forest, with consistent avoidance of open habitats and recent clear-cuts. Activity was diurnal, with peaks at dawn and dusk. Boreal individuals showed extended activity periods associated with prolonged daylight and twilight. Home ranges were approximately twice as large in boreal forests, and daily movement distances were about one third greater, indicating context-dependent behavioural responses. Conclusions Population-level differences in space use and activity of pygmy owls were consistent with contrasting landscape and photoperiodic conditions, whereas strong reliance on mature forest was consistent across regions. This dependence may constrain responses of forest specialists to rapid habitat change, emphasising the need to maintain structurally complex forest landscapes.