Animal crossings

Animal crossings

An article written by Catarina Gisby/redakta.

Nordic Road & Transport Research (2004) 16 (1): 10-11.

Animals have their own points where they cross roads and railways. They are called animal crossings and their number is increasing.
– We are learning more about these, says Lennart Folkeson, ecologist and director of research at the VTI unit Transport and Environment.

Our nature is fragmented into smaller and smaller pieces. The reason is that new roads/railways are built or because towns expand. So far, this development has not been quite so obvious in Sweden, but in Central Europe – especially in the Netherlands – fragmentation of the landscape is evident.


The term animal crossing

This term first appeared about ten years ago. An animal crossing is an installation constructed so as to make it possible for animals to pass over or under roads, railway lines and canals.

– As early as the 1960s ”wildlife bridges” were built in France, Luxembourg and the Netherlands, says Lennart Folkeson.
However, the purpose of these wildlife bridges was not to protect animals and nature; they were built to look after the interests of hunters. There was a fear that roads would prevent deer from moving from one area to another, and that this would make large tracts of land uninteresting to hunters.

– The early wildlife bridges were often too narrow and they were in the wrong places. They were also made of the wrong materials, mostly concrete. They echoed when the deer crossed, and wild animals are afraid of that type of noise. But the biologists noticed these wildlife bridges, and in turn this gave the idea for animal crossings.


Animals and the infrastructure

– When new roads and railways are constructed, what must first and foremost be borne in mind is that they must be located in areas where nature is not sensitive, says Lennart Folkeson. – If it is nevertheless necessary to locate the road or railway in such nature, the infrastructure must be adapted to the surroundings. Make sure you do not cut off known animal trails, but build the road/railway low down in the landscape so that noise from traffic does not spread very far.

Make use of the vegetation. Embed the infrastructure in the landscape. If these measures are impracticable – or do not yield the desired results – then it may be necessary to provide animal crossings.


Where and how are important

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.


More common on the Continent

Down on the Continent, there are many animal crossings at present. The Netherlands and Switzerland have been very forward looking, but in Germany, France, Hungary, Austria and Spain also the number of crossings for animals is on the increase.

In Sweden there are several animal crossings of small size, but thus far no ecoducts. There are however game-friendly bridges in Uddevalla over the E6, and at Burlöv in Skåne over the E6/E20.

– And on the ring road outside Malmö that leads to Copenhagen, a large and wide animal and recreational route has been built underneath the infrastructure, continues Lennart Folkeson.


A European project – COST 341

How much do we know about the importance of animal crossings for wild animals? Have any evaluations been made?

– Unfortunately, there were very few follow-up reviews before the latest five year period, answers Lennart Folkeson. Evaluations were a neglected area. But today we take much more care in locating the animal crossings, and we also know more as to what this type of crossing must look like to be attractive for animals.

A five-year European project on this subject, COST 341 – Habitat Fragmentation due to Linear Transportation Infrastructure – ended with a large conference in Brussels last November. Sixteen countries have collaborated in writing a European state of the art report on the basis of national reports. A handbook addressed to designers, planners and decision makers all over Europe has also been produced in English.

– It is a matter of new knowledge, says Lennart Folkeson. It takes time to reach all levels. But, on the whole, I feel that there is a positive attitude to animal crossings. In Sweden, both the National Swedish Road Administration and the National Swedish Rail Administration are greatly committed to this issue.


http://www.biology-online.org/articles/animal-crossings.html