Daniela Polic

Daniela Polic

daniela.polic@gmx.at

PDF im Hochschulschriften-Service der Universität Wien

Mobility of ringlet butterflies in high-elevation alpine grassland: Effects of habitat barriers, resources and age

Dispersal is a crucial feature for the preservation of butterfly metapopulations, which can be affected by habitat fragmentation. Each individual that leaves the habitat and enters the matrix takes a risk. Therefore, even winged organisms, like butterflies, are often extremely sedentary and spend their whole lifetime in a relatively small area. For such species, large roads may constitute a real obstacle for movement. I conducted a mark-release-recapture study on six alpine Erebia species in the Hohe Tauern National Park in order to investigate if the Großglockner Hochalpenstraße, a large and highly frequented road in an alpine environment, acts as a barrier to movement for these relatively sedentary butterflies. By studying six species which differ in body-size and ecological requirements I aimed at analysing which of the following variables predict movement probability: (a) species membership, (b) ecological specialization, (c) resource availability, (d) age or (e) patch isolation. I also estimated the population sizes of the six analysed Erebia species.
I captured a total of 429 individuals, of which 113 were recaptured. My data indicates that neither body-size nor ecological specialization significantly influenced mobility patterns in these Erebia butterflies. The road, however, seemed to be a barrier for dispersal. I found that butterflies that had to cross the road to get to another suitable habitat patch were less likely to leave the patch than butterflies that did not have to cross the road. Butterflies that were on a patch with a high nectar level were less likely to leave the patch. In addition age influenced mobility, with mid-aged butterflies being most likely to change between patches.