Wildlife & Traffic

A European Handbook for Identifying Conflicts and Designing Solutions

1 Introduction
Original version (2003)
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The problem

The consequences for wildlife of constructing transport infrastructure include traffic mortality, habitat loss and degradation, pollution, altered microclimate and hydrological conditions and increased human activity in adjacent areas. All these cause considerable loss and disturbance of natural habitats. In addition, roads, railways and waterways impose movement barriers on many animals, barriers that can isolate populations and lead to longterm population decline.

Habitat fragmentation, the splitting of natural habitats and ecosystems into smaller and more isolated patches, is recognised globally as one of the biggest threats to the conservation of biological diversity. Habitat fragmentation is mainly the result of different forms of landuse change. The construction and use of transport infrastructure is one of the major agents causing this change as well as creating barriers between habitat fragments.

As transport systems have grown, their impact on fragmentation has become an increasing problem. The steady increase in animal casualties on roads and railways is a welldocumented indicator of this problem. On the other hand, barriers causing habitat fragmentation have a long-term effect that is not that easy to detect.

To obtain an ecologically sustainable transport infrastructure, mitigation of these adverse effects on wildlife needs a holistic approach that integrates both the social and ecological factors operating across the landscape. Hence, one of the challenges for ecologists, infrastructure planners and engineers is to develop adequate tools for the assessment, prevention and mitigation of the impacts of infrastructure. This has been the task of the COST 341 Action to address the issues associated with Habitat Fragmentation due to Transportation Infrastructure

Figure 1.1 - Transport infrastructure can fragment habitats, as with this example at the A36 interchange, Alsace, Forest of Hardt (HautRhin), France. (Photo by J. Carsignol)

Figure 1.2 - Habitat fragmentation can be mitigated by building fauna passages like this overpass on the A36 motorway, Alsace, France. (Photo by J.Carsignol)