How do adults of the critically endangered hermit butterfly (Chazara briseis) utilise their habitat? (Lepidoptera, Satyrinae)

Effective conservation of specialised, endangered species depends on the knowledge of all vital resources they require within species’ lifetime. The butterfly Chazara briseis is endangered throughout Europe, especially so in all states north from the Alps. It depends on large areas of open steppe grassland with short and sparse turf. To identify resource use by adult C. briseis butterflies in relation to vegetation structure within its sites. We re-analysed mark-recapture data from the last Czech metapopulation, inhabiting a chain of volcanic hills in Ceske Stredohori highlands and hosting 2000 adults in 2006. We related adult activities observed prior to captures to visually assessed vegetation structures and land cover types obtained from aerial photographs. Additionally, we used land cover types to explore the adults’ home ranges and to compare capture points with randomly selected points. The butterflies displayed clearly structured diurnal activity with nectaring from morning to noon and courtship activities and egg-laying in the afternoons. Both sexes used short-sward patches (egg laying, patrolling), but also patches with taller, flower-rich vegetation (mating, nectaring). These results were corroborated using land cover types, however, with much lower explanatory power. Lifetime utilisation of land cover types (home ranges) differed between sexes, females utilised more shrubby and longer-sward areas than males. Randomly selected points within the sites significantly differed from capture points, the latter contained more open, either short or tall grassland patches. Management of inhabited sites must provide open, short-sward patches alternating with flower-rich taller sward and shrubby patches.