Ecological characteristics associated with high mobility in night-active moths

Mobility is an important factor influencing the range and persistence of local populations. However, mobility is very difficult to measure empirically and thus is poorly known in most taxa. Since ecological characteristics have been suggested as good estimators of mobility, we here explore the association between ecological characteristics and mobility. We surveyed night-active moths on a Swedish island, situated 16 km from the mainland, and compared ecological characteristics of the non-resident moths found on the island with those of a species pool of assumed potential vagrants from the neighbouring mainland. Species associated with high mobility were characterised by a large range, a high population density, an activity period during warm temperatures and by being habitat generalists or preferring open habitats. The generally assumed view of poly- and oligophagous species being more mobile than monophagous species was obscured by the effect of population density. Poly- and oligophagous species had higher population densities than did monophagous species, which probably explain their higher mobility found in this study. Our result highlights the need to consider the influence of ecological characteristics on mobility. This in turn will have implications for an increased understanding of distribution patterns, population persistence and how to prioritise conservation actions, especially since habitats and climate are under dramatic changes. In taxa where data on mobility are poor, ecological characteristics can be used as a proxy for mobility.