UAV-based aerial imagery to identify high quality habitats for the endangered Bog Fritillary butterfly

Context: Land use intensification has led to a reduction of valuable open habitats over the past decades. The remaining habitats are mostly small and geographically isolated from each other. Bogs and wetland habitats have suffered particularly strongly under habitat destruction and reduction of habitat quality. The Bog Fritillary butterfly Boloria eunomia occurs on little-used wet meadows and bogs, and exists today mostly in small remnant populations in Central Europe. Objective: In this study, we investigate the population ecology and habitat demands of the highly endangered B. eunomia for a remnant population and the surrounding landscape in Northern Austria. Methods: We combined habitat parameters collected on the ground with data derived from UAV-imagery and with Mark-Release-Recapture data. Results: Our study shows that the population studied is very small and that individuals behave highly sedentary. Habitat suitability depends on the occurrence of Bistorta officinalis, the butterfly´s single larval food plant, and the availability of a strong litter layer. UAV-based orthophotos enable the identification of further potential habitats for this butterfly species at a landscape level. Conclusions: Our study confirms that B. eunomia has very specific habitat requirements. With airborne data it is possible to identify potentially suitable habitats on a landscape level and thus find further potential habitats for this rare butterfly species. Intensive land management with frequent mowing and the drainage of wet meadows leads to the disappearance of such highly specialized species.