Sexual dimorphism in the alpine butterflies Boloria pales and Boloria napaea:differences in movement and foraging behavior (Lepidoptera:Nymphalidae)

Sexual dimorphism is a widespread phenomenon in Lepidoptera.It is reflected in differences in life history,behavior and morphology.Analyses of differences in behavior are mostly difficult and time-consuming,especially in high mountain ecosystems.To enhance our knowledge on sexual dimorphisms of alpine butterflies,we performed a mark-release-recapture study on 2 species common in the Alps:Boloriapales and Boloria napaea.We analysed movement and foraging behavior to investigate differences between sexes.Both sexes were mostly sedentary and the movement distances of males and females similar.However,obvious differences in dispersal behavior between the sexes were found in the movement patterns.Three different patterns were distinguished.Most males showed intensive flight activity,but mostly flew only in a limited part of the entire habitat (i.e.,their individual home range)searching for females,whereas females were less flight active and flew only to find places for oviposition or feeding.The third pattern,where individuals flew larger distances,was only observed in a small number of males,which always returned to their home range.Nearly all feeding was observed on Asteraceae.However,males preferred the genera Leontodon and Crepis,while females preferred Leontodon and Carduus.Apart from this sexual difference in foraging,individuals of both sexes were found to be more or less specialised on nectar sources.Flight activity was generally greater in males than females.Therefore,we think that sex-specific requirements in nectar ingredients exist,that is,sugar for the intensive flight activity of males and amino acids for egg production of females.

Specialized or opportunistic how does the high mountain endemic butterfly Erebia nivalis survive in its extreme habitats？

High mountain ecosystems are a challenge for the survival of animal and plant species, which have to evolve specific adaptations to cope with the prevailing extreme conditions. The strategies to survive may reach from opportunistic to highly adapted traits. One species successfully surviving under these conditions is the here studied butterfly Erebia nivalis. In a mark-release-recapture study performed in the Hohe Tauern National Park （Austria） from 22 July to 26 August 2013, we marked 1386 individuals and recaptured 342 of these. For each capture event, we recorded the exact point of capture and various other traits （wing conditions, behavior, nectar sources）. The population showed a partial protandrous demography with the minority of males emerging prior to the females, but the majority being synchronized with them. Males and females differed significantly in their behavior with males being more flight active and females nectaring and resting more. Both sexes showed preferences for the same plant species as nectar sources, but this specialization apparently is the result of a rapid individual adaptation to the locally available flowers. Estimates of the realized dispersal distances predicted a comparatively high amount of long-distance flights, especially for females. Therefore, the adaptation of Erebia nivalis to the unpredictable high mountain conditions might be a mixture of opportunism and specialized traits.