Demography and spatial dynamics of Lycaena helle ([Denis & Schiffermüller], 1775) in an alpine bog: population structure, movement, and environmental drivers (Lepidoptera, Lycaenidae)

During a study in 2025, our results indicated a large population of Lycaena helle ([Denis & Schiffermüller], 1775) in the study area, an alpine bog, characterized by a male-skewed sex ratio and high survival rates. Individual movements, mostly less than 50 m long, indicate a low connectivity between the three local population cores. Generalized linear models (GLM) showed that the distribution of the species depends on several main factors: the coverage of its host plant ( Bistorta officinalis Delarbre) the number of forest patches and their fractal dimension, the local microtopography, especially Molinia caerulea (L.) Moench tussocks, the vegetation height and the proportion of nectar-producing flowers, with few differences between sexes. Although eutrophication threatens the habitat, the current landscape mosaic seems to maintain favourable conditions. However, the low dispersal capacity of L. helle and the isolation of its populations make them vulnerable to environmental changes. We recommend the preservation of microtopography and forest edges and the creation of wooded corridors to enhance connectivity. Regular monitoring is essential to track the local abundance of this relict population, and to adjust the management accordingly.