On the ecology of the poplar admiral (<Emphasis Type="Italic">Limenitis populi</Emphasis>, Lepidoptera,Nymphalidae) in Eastern Fennoscandia

The ecology of the poplar admiral was studied in the periphery of its range for over 19 years (1990–2008), including seasonal phenomena, spatial distribution, and dynamics of abundance and dispersal of the species. The spatial organization of population of the species was studied in one of the local areas. The flying period of butterflies in Eastern Fennoscandia is divided into three phases: the observed flight of males, latent activity, and observed flight of females. The males emerge more than 10 days earlier than the females. The difference is likely to be one of the reasons for strong reduction in the butterfly abundance. The asynchrony of dynamics in different areas was explained by the influence of local factors. In the years of high abundance, the proportion of occupied areas increased. Analysis of the dispersal and abundance curves showed a trend for colonization of vacant areas. Within the occupied area, the butterflies are irregularly distributed. The presence of areas with constantly moist soils and aspen trees in the forest stands are the main factors responsible for butterfly aggregations. Observations of the marked individuals showed that the maximum distance covered by a butterfly was 4.8 km. The butterfly moved freely across all the study area, and no single accumulation of butterflies isolated from the others was recorded. All the movements are shown to be local. The distance of these movements, according to the exponential model, reached 6–7 km; the grouping itself is classified as a subpopulation, i.e., a structural unit of a large spatially differentiated population. The high mobility of the poplar admiral ensures migration of individuals between the populations and colonization of vacant habitats.