Abstract (eng)
This thesis targets the characterization of favourable larval habitats for the southern festoon (Zerynthia polyxena) in the metropolitan area of Vienna. Starting from a mapping of the larval host plant Aristolochia clematitis (European birthwort) in 2019, possible habitat patches were surveyed in 2020 for the presence of larvae. Habitat requirements of Z. polyxena are dominated strongly by larval needs and are generally well known, however respective quantitative studies from Austria are missing so far. The research design incorporated detection of larvae by standardized scanning of host plant habitats and surveying biotic as well as abiotic site parameters on several spatial scales.
At 53 of 95 locations pre-imaginal states could be verified. Results show that the number of food-plant shoots as well as patch size had a significant positive effect on the occupation of habitats by larvae. These were the most meaningful factors besides connectivity of sites. Especially the distance to the nearest occupied site was important for occurrence of larvae. Occupied larval habitats showed less distance among each other than unoccupied habitats. Further, site occupancy was not related to distances between study sites to the nearest forest edge or water body. Analysis of surrounding landscape structure (50 m radius) showed that canopy cover had a negative effect on larval occurrences. Concerning microhabitat attributes, shading, the number of host-plant leaves and plant height were not related to presence of larvae, whereas the factor flowering shoots had a positive effect. Z. polyxena is protected according to EU nature conservation law in Annex IV. For documentation, a regularly monitoring should take place, and if necessary, intervened by appropriate management and protection measurements.