Predicted 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 wildlife densities within an area that is considerably larger than the actual road or railway corridor. For birds, an extensive meta-analysis has identified an average of 20% density reduction within 1 km from the infrastructure. I investigated to what extent this density reduction can be expected to compromise the habitat quality and conservation value of Swedish Natura 2000 areas designated for the protection of birds (Special Protection Areas; SPAs). The majority (63%) of Swedish SPAs are, to some extent, found within this 1 km road/railway effect zone (REZ). The total overlap between SPA and REZ is approximately 126,000 ha or 4.2% of the country’s SPA area. There are, however, large differences amongst bio-geographical regions. In the southern (continental) and coastal regions combined, 25.8% of the total SPA area fall within REZ, representing an estimated 4–7% reduction in bird abundance within SPAs. The probability of overlap with REZ 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 for maintenance and restoration of biodiversity within the EU. I recommend placing a stronger emphasis in the management of Natura 2000 sites on the threats to wildlife conservation caused by transport infrastructure and traffic. Special attention should be paid to sites with a large overlap with the REZ and sites hosting particularly vulnerable taxa or habitats. Infrastructure owners and managers should make their best efforts to minimise and compensate for the negative impacts of roads and railways and associated traffic in SPAs and other protected areas.