Resource use by the dryad butterfly is scale-dependent

Anthropogenic disturbance promotes the abundance of a newly introduced butterfly, the European common blue (Polyommatus icarus; Lepidoptera: Lycaenidae), in Canada

The frequency of introductions of non-native species is increasing worldwide, but only a few introduced species undergo rapid population growth and range expansion, and even fewer become invasive, leading to negative impacts on native communities. Predicting which non-native species are likely to become widespread and abundant can be difficult when there is a lack of species’ information in the early stages of colonization. Here, we investigate the ecology of a newly introduced butterfly in Canada, the European common blue (Polyommatus icarus (Rottemberg, 1775)), by modelling its local- and landscape-scale habitat suitability in Montréal, Quebec, Canada, and the surrounding region, and by assessing its dispersal ability using a mark–release–recapture study. At a local scale, we found that P. icarus abundance was highest at sites with moderate levels of habitat disturbance (e.g., mowed every 2–3 years), the presence of their preferred larval host plant and low proportional cover of grasses. At a landscape scale, P. icarus abundance increased with an increasing proportion of urban area and decreasing proportion of forests. We also found that P. icarus is a low to moderate disperser relative to other butterflies. Our results suggest that P. icarus may become widespread in disturbed and urban areas across Canada, but that further investigation into additional potential range-constraining factors (e.g., microclimate), especially larval preferences, and modelling of the trajectory of P. icarus range expansion is needed.