Within-habitat vegetation structure and adult activity patterns of the declining butterfly Euphydryas aurinia

Abstract

BackgroundEuphydryas aurinia is a declining butterfly inhabiting oligotrophic grasslands in Central and Western Europe. Despite numerous ecological studies, patterns of its adult activity have so far been rather neglected, although adult resource use contributes to resource-based understanding of insects’ habitats.AimTo relate E. aurinia adult activity patterns to within-habitat vegetation structures.Methods(1) Timed adult activity observations along a transect crossing a colony site, analysed via partial ordination methods. (2) Activity records obtained during mark-recapture, analysed via binomial regressions.ResultsBoth methods, besides influences of weather, time of day (similarities between morning and late afternoon hours), and progression of season (mate locating replaced by maintenance activities), revealed consistent association of behaviours to vegetation structures. Of the two male mate-locating behaviours, perching occurred near shrubs and woodland edges, and patrolling over centres of inhabited meadows. Female activity concentrated in nectar-rich mid-height sward near host plants. Consequently, male and female activity were partly spatially separated.Implications for conservationA habitat for E. aurinia should provide resources for all its activities in close proximity. Grasslands containing host plants should be dissected by structures such as shrubs, woodlot edges, or taller herbaceous vegetation, emphasising the importance of landscape heterogeneity for insect fauna.