Study site and sampling
The study site is an area of coastal dunes in the southwest corner of Bold Park (3185700600S, 11584502100E), in City Beach, Perth. The site comprises areas Acacia I and Open I of Johnson (1980), with an abrupt (,5 m) transition between a dense thicket of Acacia rostellifera bushes and low, sparse dune vegetation. Snails were censused in autumn or winter (late March to early August) each year from 1977 to 2010, along a transect across the two habitats.