Introduction

The Netherlands is becoming warmer as a result of climate change, and because of this various plant and animal species are invading the country from warmer, more southerly areas. Most of the new arrivals in the last century are from the south ; few species have arrived from the north.

In various species groups there are good examples of southern species that are increasing : the wasp spider, the oak processionary moth, the crimped gill fungus, and various lichen species. Marine species from further south are also more frequent in Dutch coastal waters, such as the small hermit crab, the sea squirt Didemnum lahillei, the scaldfish and the lesser weever fish.

As well as changes in species distribution, there has also been a shift in the growing and flowering seasons for plants and in the breeding season for birds. This could impact on numbers of breeding birds, especially in the species that overwinter in Africa, such as the pied flycatcher.

Not all of the increases in southern species are attributable to climate change. Some of the newcomers prefer towns and industrial areas because these built-up habitats have a warmer climate than the surrounding countryside.

Lichens and climate change

As a result of climate change, lichen species from southern Europe that prefer warmer climates are becoming more common in the Netherlands.

Trends

Since 1989 there has been an increase in the lichen species that prefer warm climates, and a decrease in the lichen species associated with cool conditions. Climate change is thought to be responsible for this. No such changes were observed between 1979 and 1989.

Recent changes in species composition have been reinforced by ammonia pollution, because proportionally more of the northern species do not tolerate high levels of nitrogen and therefore decline faster.

Fish and climate change

The increase in the scaldfish and lesser weever fish along the Dutch coast is possibly a result of the warmer climate in the Netherlands.

Trends in the scaldfish

The scaldfish is found from the Mediterranean up to the south of Norway. Though scarce in Dutch coastal waters, catches of this species have increased considerably in the last 10 years. This could be a result of the warmer climate.

The scaldfish is a slow-growing flatfish. A fish 14 cm long could be 13 years old. The diet of this species consists primarily of crustaceans and worms, and also small fish such as black goby.

Trends in the lesser weever fish

Catches of the lesser weever fish in Dutch coastal waters have also increased considerably in the last 10 years. This species is found from the Mediterranean as far as the centre of Danish waters. Its increase could also be the result of a warmer climate.

The lesser weever fish is mostly found on sandy seabeds. Individual fish grow to about 18 cm long by their sixth year. The lesser weever fish buries itself in the sandy seabed, so that only its eyes protrude above the surface. Its diet consists mainly of black goby.

Migrants to Africa and climate change

Climate change can impact on the migratory birds that breed in the Netherlands and overwinter in Africa.

Trends in birds migrating to West Africa

The warmer Dutch springs can disrupt the breeding behaviour of migratory birds, such as the pied flycatcher. This can cause the species to decline.

On average, however, no decline has yet been observed in the group of birds that migrate to West Africa. In fact, more species in this group are increasing in number than are declining. Many species in the group (including the sedge warbler and whitethroat) have benefited from the higher rainfall experienced in West Africa south of the Sahara in the last fifteen years. The only species that have declined in numbers are the great reed warbler, black-tailed godwit and wheatear, but this is more to do with a deterioration of the breeding areas in the Netherlands than with the warmer springs.

Trends in birds migrating to elsewhere in Africa

The species that overwinter in east, central and southern Africa have declined as a group since 1990. Examples are the wood warbler, house martin, icterine warbler and turtle dove. The reason for their decline is unknown, but there are no indications that cimate change plays a role.

* West Africa : bluethroat (increase), pied flycatcher (stable), tree pipit (increase), marsh warbler (stable), marsh harrier (increase), whitethroat (increase), great reed warbler (decrease), Sandwich tern (increase), black-tailed godwit (decrease), reed warbler (increase), avocet (stable), spoonbill (increase), sand martin (increase), purple heron (increase), sedge warbler (increase), grasshopper warbler (increase), wheatear (decrease), garden warbler (stable), common tern (stable), honey buzzard (stable), garganey (stable) and black tern (stable). * East, central and southern Africa : swallow (decrease), hobby (stable), lesser whitethroat (increase), willow warbler (stable), wood warbler (decrease), redstart (stable), swift (no clear trend), red-backed shrike (stable), spotted flycatcher (decrease), house martin (decrease), cuckoo (decrease), nightingale (increase), whinchat (decrease), Savi’s warbler (increase), icterine warbler (decrease), golden oriole (stable) and turtle dove (decrease).