Shift in the distribution of insects and molluscs

Climate change is making the Netherlands more suitable for southern species. The repercussions of this are already visible in some groups of insects and in molluscs.

Trends in southern species

Southern species are those species whose area of distribution extends as far north as the Netherlands or lies further south. Most southern species are extending their area of distribution northwards, presumably because the climate is becoming warmer. They include ground beetles, dragonflies, hoverflies and molluscs. The species that appear to be expanding northwards are those that develop fast, spread easily and do not demand much from their habitat.

Far fewer southern species are shifting their area of distribution southwards. The main southern species that are shifting south rather than north are bees. They seem to be doing so because suitable biotopes are disappearing. Most of them are species that occur in natural, stable biotopes, and in the Netherlands these biotopes are dwindling rapidly.

Trends in northern and eastern species

The table under "additional information" also shows changes in the distributions of northern and eastern species. Northern species are species whose area of distribution extends southwards into the Netherlands. Although it seems feasible that climate change would cause their area of distribution to contract northwards, there are too few species to be able to discern a trend.

Eastern species are those whose western boundary runs through the Netherlands. They can be expected to expand further westwards in response to the warmer summers. In this species group the number of shifts westwards is almost as large as the number of shifts eastwards.

Trends in other invertebrates

Other species groups displaying a shift in their area of distribution include the wasp spider and the oak processionary moth.