Corridors for small animals

Corridors for small animals
While building streets one has to think of amphibians and small animals. © Conseil Général Isère

Involved sectors

Forestry, Hunting, Nature protection, Transport, Local population/citizens

Affected habitats

Areas for settlements and transport


Underpasses for small animals are pipes made from concrete or steel which are incorporated into the road-body crossways or at angles as crossing aids for small mammals, amphibians, reptiles and invertebrates. Conduits obstruct animals’ free access to the road and lead them to the underpasses. An uninterrupted link between the conduits and the underpasses is essential. The conduits should run parallel to the road, and should if possible be supplemented with guide structures placed at right-angles to the tunnel openings. These crossing aids for amphibians and small animals should be incorporated at an early stage during road-building and should be ready for operation before traffic is permitted to use the road. Retrofitting of these systems is rarely possible due to the high costs involved. The advantage of these permanent protection systems is that they work all year round and require very little management.


Impact in particular on Small mammals, Reptiles, Amphibians, Insects
Ecological impact  
Reduction of fragmentation or creation of new valuable habitats If properly planned and implemented, underpasses for small animals can greatly reduce the fragmentation effects of linear infrastructure systems.
Other The installations can greatly reduce the number of animals killed on the roads, especially during seasonal amphibian migrations, and thus have positive impacts on populations.
Time of realisation for measure Immediate: As soon as the system is installed on the affected section of road, guide structures lead the animals to the underpasses.
Impact scope Local (municipality): As most of the target species have relatively small ranges, the impact is generally fairly localised.


Implementation period Weeks: Particularly sensitive sections of existing roads are generally well-known. When installing new systems, studies are required. Installation can take place fairly rapidly.
Frequency Non-recurring: Installation a single activity, but regular care and checks are essential.

Economic and legal aspects

Costs Medium (10'000-100'000 EUR): Relatively low costs if installed during road-building; retrofitting is very complex and expensive.
Socio-economic impacts No direct impact
Sources of financing Public: local, Public: regional, Public: European

Further information

Evaluation Thanks to the conduits and guide structures, the underpasses are generally very effective and are used by a wide variety of animal species.
Information Other: Nature conservation associations, especially those working with amphibians and involved in the seasonal amphibian migrations.
Contact Other: e.g. NABU, WWF, Pro Natura.

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