Managing an endemic taxon at the verge of extinction: factors driving population persistence and larval microhabitat selection of Zygaena angelicae elegans (Lepidoptera, Zygaenidae)

Abstract The shift towards “close-to-nature forestry” in Central Europe led to an area-wide decrease of open forest structures and a decline of many photophilous species or taxa. One of them, the endemic taxon Zygaena angelicae elegans , only occurs on the western margin of the Swabian Alb, Germany. Five of only 37 (mostly small) populations became extinct since 2000; hence, this evolutionary significant unit is at the verge of extinction. We assessed landscape-scale drivers of population persistence by comparing contemporary surveys with data from the 1990s and analysed larval microhabitat selection to provide target values for habitat management, which we tested in a case example. While population size was highest in open, south-exposed slopes, population persistence strongly decreased with increasing distance to the next occupied patch, with high extinction risk above 1.3–1.5 km. Occurrence and abundance of larvae was mostly driven by afternoon insolation (> 135 min) and the availability and height of the larval host plant Coronilla coronata (> 15 and > 25 cm for occurrence and abundance, respectively), which in turn depended on low canopy (< 61%) and shrub cover (< 26%). Implications for insect conservation Habitat management reducing forest encroachment based on these thresholds resulted in an immediate boost of local population size. Management plans targeting a stable metapopulation must focus on the expansion of current relict habitats and creation of new habitats in close vicinity (1.5 km) to existing populations, with rapid population responses indicating that a consequent implementation may save the highly endangered taxon from extinction.