Seasonal change in nectar preference for a Mediterranean butterfly community

A decline in butterfly diversity and abundance has been observed all over Europe, even for rather widespread species. The reasons for this trend are not clear, with one of the possible mechanisms being a decrease in available nectar sources. In the scope of these observations, the nectar sources used by a Mediterranean butterfly community have been analyzed. Clear differences between specialist and generalist species could be observed. However the specialization rate was not stable throughout the year, both considering the butterfly community as a whole and for individual species. When analyzing the temporal variability in nectar use between the seasons, an increasing specialization in nectar use was observed in autumn. While a seasonal trend could be attributed to a change in butterfly species composition, the trend towards more specialization from summer to autumn was related to a change in relative abundance of flowering plants relative to the richness of butterfly species and abundance present. Significantly fewer flowering plants were present in degraded Mediterranean systems during autumn.