Reptile conservation in Giswil.
Bauen und Unterhalt21.07.2023Sidonie Gaillard
The planned renovation of the Zentralbahn route in Giswil includes extensive reptile conservation measures. The replacement habitats and resettlement projects are intended to ensure that the vulnerable sand lizard can continue to live along the railway line. With these measures, Zentralbahn is contributing significantly to the preservation of biodiversity in the canton of Obwalden.
Distribution of the “vulnerable” sand lizard.
Zentralbahn is planning comprehensive track renovations between Giswil and Kaiserstuhl. The sand lizard (Lacerta agilis) is known to inhabit a section of approximately 1.25 kilometres from Giswil train station to Ächerliwald. The sand lizard is classified as “vulnerable” on the IUCN Red List of Threatened Species. Its main habitation area is in the lowlands and its population is decreasing. The decline in numbers is associated with intensified agriculture. As a result, the animals are moving to other anthropogenic habitats that can still meet their needs (for now). It is not uncommon for the lizard to use railway embankments and adjacent tracks as habitats.
Sand lizards are highly sedentary. They remain in their habitats for years. Reptiles need to thermoregulate on a daily basis, requiring access to high temperature gradients within a small area. Underground structures provide night-time hiding places, offer protection from adverse weather conditions and are used as winter quarters. The habitats must provide all the resources the animals need if they are to be inhabited long-term.
Habitat of the sand lizard in Giswil.
In Giswil, the sand lizard primarily uses the immediate area around the tracks as its habitat. Wooden railway sleepers, old concrete curb walls backfilled with gappy material and extensive plant cover provide the sand lizards with ideal living conditions. But these ageing track elements are to be replaced in order to ensure continued safe rail traffic. Unfortunately, the sand lizards will lose part of their habitat. Zentralbahn is taking this into account by implementing extensive reptile conservation measures.
New replacement habitats.
The goal is to relocate the reptiles and keep them out of the renovation perimeter before the start of construction on 2 October 2023. Replacement habitats, which will remain in place permanently, were installed at 11 locations along the route in spring 2023. These small structures, a mixture of wood, stones and sand, are located near the route but outside the renovation perimeter. Due to the sloping terrain, it was necessary to stabilise the new structures with Ribbert eco-grids.
Temporary and permanent installations.
The next step was to install reptile fences. The fences help to keep the lizards are kept away from the renovation perimeter. From spring 2023, animals within the renovation perimeter will be captured and relocated to the new habitats. For this purpose, among other things, scraps of white fleece were spread out to serve as potential cover for the lizards. To help them get used to the new locations and stop them from heading straight back into the renovation perimeter, the replacement habitats are also fenced off and protected against predators with a net. The resettlement procedure described in the section above will be carried out in several stages and, if necessary, continued until shortly before construction begins.
If hibernating animals are discovered during the renovation work in autumn 2023, they will be taken to a safe location to hibernate.
To enable the sand lizards to recolonise the renovated route in Giswil, all reptile fences will be removed after the construction work is completed. In addition, small structures will then be created right next to the route, supplementing the available habitats. With these comprehensive reptile protection measures, Zentralbahn is ensuring that sand lizards can continue to live along the route in Giswil.