Population size, density, spatial distribution and dispersal in an Austrian population of the land snail Arianta arbustorum styriaca (Gastropoda: Helicidae)

摘要

A population of the land snail Arianta arbustorum styriaca endemic in the Northeastern Alps in Austria was investigated with regard to population size and density, spatial distribution and movement patterns of the individuals in order to obtain basic information on their population biology. The study was carried out at a site situated about 880 m above sea level in Styria, in the Gesause mountains over two years, using the capture-recapture technique. Population density based on the Jolly-Seber model showed variation ranging from 0.12 to 4.03 individuals/m2 over the whole study period. The recapture rate after one year was generally high (up to 85% per sampling date). In most cases individuals were aggregated. The snails showed a high site fidelity; average calculated minimum areas were 0.115 m2/day. The sum vector of all individual dispersal observations over the entire study period did not indicate a significant preference for any direction. Only during winter was a significant downhill displacement (possibly passive) detected.