The grass snake in Hollands Noorderkwartier
The grass snake lives in various places in our water-rich management area. As a predator of mice, fish, amphibians, and insects, and also as prey for herons, foxes, polecats, and hedgehogs, the grass snake plays an important role in our ecosystem and food chain. The grass snake is shy and non-venomous, so it is certainly harmless to humans.
Fragile hose
Nationally, the grass snake is a fairly rare species and is therefore included on the Red List – Vulnerable. This cold-blooded animal needs warmth to become active and likes to bask in the sun on the asphalt in the morning. This is a dangerous habit; many grass snakes meet their end as roadkill. But their vulnerability is also a consequence of the fragmentation of their habitat.
Strengthening populations
As the map shows, there are several populations living in the Zaan region, near Marken, and in the vicinity of Etersheim that are no longer able to interact with each other. This increases the risk of inbreeding, making grass snakes more susceptible to diseases and disorders. Initiatives by grass snake working groups and nature conservation organizations are attempting to strengthen and bring together these populations.
Working together for protection
Because grass snakes live in water-rich areas, and dykes make up a significant part of their habitat, HHNK also sees a role for itself in protecting grass snakes. We work together with nature conservationists to bring populations together, limit damage to the habitat and communities during dyke work as much as possible, and contribute to the construction of breeding piles and winter shelters.
Winter lodgings on the embankment
The Markermeer dikes are being reinforced over a length of tens of kilometers to protect the hinterland from flooding. The implementation of this project goes hand in hand with strengthening biodiversity. This is also the case in Hoorn, where winter shelters have been built on the sand that now forms the flood barrier. Together with archaeologists from the municipality of Hoorn, we have created winter shelters for grass snakes and breeding sites for sand martins on the embankment.
Reuse of archaeological finds
A unique feature of this project is the reuse of old retaining stones from the 16th century. These stones were once part of the Westerpoort gate and the fortifications on the sea side of the city. On the embankment, they are being given a new purpose as building blocks for winter shelters for grass snakes. The core consists of small stones that have been sifted from the newly applied soil. The grass snakes slide through the cracks and find their way to the safest spot. The outer layer consists of larger stones, including the old stones from the city wall. This creates a frost-free winter shelter for grass snakes.
Read also the article about the origin of the stones in archaeology West Friesland.
Grass snake habitats in the dike
In other places, when reinforcing the Markermeer dikes, shelters for grass snakes were built into the dike itself, such as in the Uitdammerdike. New shelters were built using the stones that had previously formed the winter shelters.
