DATA: Distribution of the two-tailed pasha, Charaxes jasius, in fragmented landscapes assessed with bait traps: effects of spatial scale and connectivity

Understanding how landscape structure influences species distribution is essential for biodiversity conservation in fragmented habitats. We investigated the spatial ecology of the two-tailed pasha, Charaxes jasius (Linnaeus), an emblematic Mediterranean butterfly whose larvae feed almost exclusively on the strawberry tree (Arbutus unedo L.). Using 1,666 bait traps deployed over seven years at a regional level across a heterogeneous landscape in south-western Iberia, we modelled both abundance and occupancy in relation to host plant cover at eight spatial scales, functional connectivity, distance to the nearest host patch and forest habitat type. Connectivity was estimated using Hanski’s index, considering host patches as sources and traps as ecological sinks, thereby capturing a continuous gradient of host influence across the landscape. Our multi-model inference showed that occupancy was negatively related to distance from the nearest host plant patch and positively to host plant cover. The effect of host plant cover was the strongest at spatial scales of 5–6 km. Occupancy was also significantly higher in cork oak and Pyrenean oak than in Holm-oak woodlands. Non-zero abundance was significantly positively related to functional connectivity. Random effects of district and year highlighted the relevance of spatial and temporal variability. Most individuals were recorded close to host plant patches, but a small fraction occurred at greater distances, extending up to 5–20 km. Implications for insect conservation Our findings underscore the importance of the distribution of the host plant but also broader landscape-scale configuration—including non-host patches that may provide critical adult resources—when assessing spatial habitat use by C. jasius in fragmented ecosystems, with key implications for management/conservation planning.