Potential impacts of transport infrastructure and traffic on bird conservation in Swedish Special Protection Areas

Abstract

The ecological impacts of roads and railways extend into the surrounding landscape, leading to habitat degradation and reduced animal densities within an area that is considerably larger than the actual road or railway corridor. For birds, an extensive meta-analysis has pointed at an average of 20% density reduction within 1 km from the infrastructure. I investigated to what extent this density reduction could potentially compromise the habitat quality and conservation value of Swedish Natura 2000 areas designated for the protection of birds (Special Protection Areas; SPAs). A majority (63%) of Swedish SPAs are at least to some extent found within this 1 km potential effect zone. The total overlap between SPA and effect zone is 126,000 ha, or 4.2% of the countrys SPA area. There are however large differences among biogeographical regions. In the southern (continental) and coastal regions combined, 25.8% of the total SPA area fall within the effect zone, representing an estimated 4-7% reduction in bird abundance within SPAs. The probability of overlap with effect zone is higher for larger SPAs. However, the proportion of overlap is higher for smaller SPAs, and accordingly smaller sites can be assumed to experience a greater impact from transport infrastructure and traffic. The impacts on Natura 2000 sites are particularly concerning as this network of protected areas is a cornerstone to maintain and restore biodiversity within EU. I recommend putting a stronger emphasis in the management of Natura 2000 sites on the potential threats to wildlife conservation caused by transport infrastructure and traffic. Special attention should be paid in sites with a large overlap with the effect zone, and in sites hosting particularly vulnerable taxa or habitats. Infrastructure owners and managers should do their best to minimize and compensate for the negative impacts of roads and railways and related traffic in SPAs and other protected areas.