Aspects of the Ecology of Helix pomatia L.

Abstract

(1) Information on the distribution of Helix pomatia shows that while it occupies several different habitat types it is, in most of its range in England, largely restricted to aspects facing approximately south. (2) Intensive studies on a single population show the dependence of activity, mating and egg-laying on rainfall. The breeding biology is described. The growth rate of immature snails is very variable. (3) An earlier classification of adult snails into growth classes is shown to be into age classes. Older snails hide themselves amongst vegetation less than younger snails but are less mobile. (4) The adult snails in one site showed a regular seasonal pattern of movement, away from, and later back to, hibernation areas. The particular pattern of movement of individual snails seems to be repeated from year to year. The known `homing' ability is believed to be related to the existence of permanent hibernation areas. In a linear hedgerow individual snails returned to hibernation sites but there was no overall directional pattern of movement affecting the whole population in the hedge. The difference between the two sites was believed to be related to the availability of sites suitable for egg-laying. (5) Observations in the field showed a strong preference for feeding on two species of Centaurea. (6) Known predators of young and adult snails are listed and a possible disease briefly discussed.