Human-disturbance and caterpillars in managed forest fragments

The impact of forest-edge habitat on Lepidoptera assemblages has been well-studied, but the impact of trailside habitat has rarely been considered. We surveyed caterpillar populations in relation to recreational trails at 72 quadrats in four forest fragments in southeastern, Quebec, Canada. We found a consistent negative relationship between trails in the forest and both the abundance and species diversity of caterpillars within and among forest fragments. Conversely, caterpillar presence was not related to the presence of favorable host trees at a given quadrat. We suggest that the negative effect of trails may be due to increased predation pressure in trailside habitat and to conditions that make trailside habitat less preferable for oviposition. These results underscore the importance of managing trails to limit the amount of intra-forest disturbance experienced in important forest fragment remnants.