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

One population of the land snail Arianta arbustorum styriaca(Frauenfeld, 1868), endemic in the Northeastern Alps in Austria,was investigated with regard to population size and density,spatial distribution and movement patterns of the individualsin order to obtain basic information on their population biology.The study was carried out at a site situated about 880 m abovesea level in Styria, in the Gesäuse mountains over twoyears, using the capture–recapture technique. Populationdensity based on the Jolly–Seber model showed variationranging from 0.12–4.03 individuals/m² over the whole studyperiod. The recapture rate after one year was generally high(up to 85% per sampling date). In most cases individuals wereaggregated. The snails showed a high site fidelity; average calculatedminimum areas were 0.115 m²/day. The sum vector of all individual dispersalobservations over the entire study period did not indicate asignificant preference for any direction. Only during winterwas a significant downhill displacement (possibly passive) detected. (Received 20 April 1998; accepted 12 September 1998)