Landscape properties and density dependence shape movement patterns of three threatened butterflies

Abstract Context. Conservation of endangered species necessitates an in-depth understanding of their ecological requirements. Particularly in landscape ecology, the behavioural tendencies of threatened butterfly species in Gotland, a biodiversity-rich island in the Baltic Sea, become crucial. Objectives. The primary aim of this study was to elucidate the movement patterns of three threatened butterfly species—Euphydryas aurinia, Parnassius apollo, and Phengaris arion—in Gotland and to identify the influence of specific land characteristics on these patterns. Methods. The study was conducted from 2017 to 2020 within a 60 km² area in Gotland. Data collection involved 29,584 captures, encompassing 16,223 distinct individuals. Variables such as open vegetated land, ground moisture index, and forest cover were assessed. Results. Among the 4821 arrivals and 5083 departures documented, the species exhibited differential responses to the evaluated habitat features. Both E. aurinia and P. apollo displayed a positive density-dependent dispersal, while P. arion's movements were not significantly associated with any habitat features examined. Landscape properties like open vegetated land and ground moisture index statistically influenced the likelihood of arrival and departure. Conclusions. The study accentuates the intricate relationship between land cover and the behavioural tendencies of the subject butterfly species. It has broader implications for the targeted habitat management strategies that would benefit threatened butterfly populations in Gotland.