A survey of land molluscs of the South Haven Peninsula carried out by C. Di
ver and C. Oldham in the 1930s was used as a basis for resurveying in 1999,
albeit with different methodology. Significant changes have occurred, with
a net increase in species diversity and in distributions of many species.
Some of these changes are associated with parallel habitat changes both nat
ural lard anthropogenic. Only a few reflect national trends; others appear
to track local changes with some time lag. Some species have not yet reache
d new areas of apparently suitable habitat.