The grass snake predominantly occurs in three more or less separated core areas around the IJsselmeer (former Southern Sea). The most important populations are in the provinces of Noord-Holland, Utrecht, Gelderland, Overijssel, Drenthe and Friesland. Grass snakes have colonised the 40-year old province of Flevoland (reclaimed land in the former Southern Sea) which is playing an increasingly important role in connecting the three core areas. In the southern provinces no natural populations are present. A few years ago, however, grass snakes were discovered in the south-eastern part of the province of Limburg, which is most probably a result of colonisation from Germany. Introduced populations exist throughout the country.
The grass snake is listed on the Red List as vulnerable. It is strictly protected under Dutch legislation and listed on the Bern Convention (Annex iii). The coverage of the grass snake decreased by 37% since 1950. The decrease is caused by intensification of agricultural practices, habitat fragmentation, lowering of ground water levels and canalisation of rivers, streams and brooks. The disappearance of middens near farms has reduced egg laying opportunities, but it is not known to which extent this has contributed to the decline of the grass snake. The species will benefit from measures that counteract the effects of habitat fragmentation, increase the amount of suitable habitat and prey species (creation of ponds and marshes) and improve reproduction (provision of compost heaps).
Delft, J.J.C.W. van, Wijer, P. de, Zuiderwijk, A.
- Creemers, R.C.M. & J.J.C.W. van Delft 2009. De amfibieën en reptielen van Nederland. Nederlandse Fauna 9. Nationaal Natuurhistorisch Museum Naturalis, KNNV Uitgeverij & European Invertebrate Survey-Nederland, Leiden.