Context-Dependent Movement Responses of Large Carabids to Forest Gap Cuttings

Continuous cover forestry aims to mimic natural disturbance dynamics and thus preserve the structure of uneven-aged, semi-natural forests. A common practice within this silvicultural system is the selective logging of single trees or small groups of trees, creating small-scale canopy gaps that can modify local environmental conditions and potentially affect the movement of ground-dwelling insects. Here, we examined movement responses of two large, flightless carabid beetles, Carabus coriaceus and C. ullrichii (Coleoptera: Carabidae), in a managed oak-hornbeam forest in Hungary. Using radio telemetry, we tracked 27 individuals at 8-h intervals for up to ten days following release in either gap cuttings or adjacent closed-canopy forest. Individual movement trajectories were quantified using daily dispersal, net displacement, and hidden Markov models to distinguish random walks (a proxy for foraging) from directed movements (dispersal). The two species showed contrasting movement patterns. Carabus ullrichii had shorter step lengths and occupied smaller spatial areas, with lower daily dispersal in gap cuttings than in closed-canopy forest and only marginal sex effects. In contrast, the movement of C. coriaceus was unaffected by gap cuttings, suggesting limited sensitivity to this habitat type, but strongly sex-dependent, with males covering larger daily and net distances and showing a higher tendency for directed movement than females. The proportion of random walks did not vary with habitat in either species. Our results demonstrate that even small-scale forestry interventions can trigger highly species- and sex-specific movement responses, revealing behavioral shifts that remain entirely undetected by traditional, assemblage-level sampling approaches such as pitfall trapping.