Kansen voor de ringslang langs het spoor in Noordwest-Nederland

Nesting opportunity for the Grass Snake on railway embankments In the intensively used Dutch landscape, suitable habitat for the reptiles is becoming more and more scarce. Most species are restricted to nature reserves, only the Grass snake (Natrix natrix) is able to maintain populations outside nature reserves and is known to have populations in (sub) urban areas. Railway embankments play an important role for these (sub)urban populations as they do provide some key-elements for the Grass snake: the drainage ditches provide good hunting ground, the rough vegetation offers shelter, food and basking spots and the embankment can serve as a hibernationsite. However, there is one drawback: a place where the snakes can deposit their eggs is often missing. Creating reproduction sites by constructing heaps of organic material for egg-laying, as in a compost heap, could improve this potentially promising habitat. In order to help in the conservation of this species, ProRail, the Dutch company responsible for the maintenance of the railways, commissioned a study into man-made egg-laying heaps along embankments in the north western part of the Netherlands. The aim was to discover old heaps as well as potential sites for new ones. Locating an egg-laying site on a railway embankment brings particular problems, such as no hinder to trains, and ensuring the safety of both snakes and the people concerned with constructing or maintaining the heaps. The volunteers who usually carry out such work would have no access. Land ownership also comes into play; some parts of the embankment are privately owned. Sites were selected from maps according to the presence of a railway within the distribution range of Natrix natrix and of a good hunting area for the snake. The sites were visited in the summer. An egg-laying heap needs to comply with a number of condition, such as size, composition and humidity; manure is not recommended in this case. It is also important that the heap is replenished with fresh material every other year so that it can continue to generate warmth and serve as an egg-laying site. This autumn several breeding heaps will be created on railway embankments. Creating such heaps in suitable habitat could also be useful for Grass snake populations in other parts of the Netherlands as the creation of such artificial egg-laying sites is regarded as an very effective conservation measure for the Grass snake.