Depending on which animals they are intended for, animal crossings look different. If it is small amphibians whose movement is to be enabled, tunnels under the road are recommended. If large game are to be able to move from one area to another, perhaps an ecoduct will be needed.
– An ecoduct is a structure that is built over a road/railway to provide a connection between areas of nature on each side. The surface is covered with soil so that vegetation can be established. In principle, all animals – and also plants – can move across an ecoduct, says Lennart Folkeson.
Animal crossings may have several aims.
Daily foraging is perhaps the most obvious of these.
– Many animals use different biotopes to search for food and to rest, and therefore they daily move between different parts of the landscape, says Lennart Folkeson.
But it is at least as important for animals to be able to look for a mate over larger areas, so that inbreeding may be prevented. And if there are too many animals of the same species in a certain area, it must also be possible for them to spread into other areas.
Other animal species are ”programmed” to undertake long migrations at a certain part of the year.
– When an animal crossing is planned, it is essential to decide what is the principal purpose of the crossing, emphasises Lennart Folkeson.
The location of the crossing must then be chosen with great care.
– An animal crossing must be located at a point where animals are known to cross, not a kilometre further away where they will never go.
What the junctions between the crossings and the surrounding landscape look like is very important. It must be natural for the animals to move up into an eco-duct, and the nature in the ecoduct must not abruptly differ from that on each side. The ecoduct must be perceived as part of the ecosystem.
Fences are another detail of great importance.
On the ecoduct there must be fences to prevent animals falling down into the road/railway, and the road/railway itself must be fenced so that the animals are guided to the crossing. The base of the crossing must be soil or vegetation. And it is best if the animals can see from one side to the other.
– Good visibility is also important for tunnels, adds Lennart Folkeson. Foxes and badgers will enter narrow passages, but most large animals are frightened when the passage is narrow and they feel trapped. Most animals want to be able to see the other end.