Taking the high road: treetop bridges for arboreal animals (formerly titled, Walking at height)
The major impact of habitat fragmentation results from the barrier effect caused by the construction and use of linear infrastructure of transportation systems. Habitat fragmentation can be described as the splitting of natural habitats and ecosystems into smaller and more isolated patches. Habitat fragmentation is recognized as one of the most important global threats to the conservation of biological diversity. Fauna passages are constructed to minimize the negative effects of habitat fragmentation. However, there are only some vague ideas about measures for tree-living mammals (excluding bats). Some anecdotal stories, collected by this author from the international network and from discussion with interested people, helped to develop some thoughts for the design and construction of tree-bridges. There is some information about measures for squirrels, dormice, monkeys, possums, and pine marten. These species, for which such measures could be fruitful, are sometimes very common and well known by the public: e.g., squirrels; and sometimes rare and only known by specialists and biologists: e.g., several obscure possums. This presentation offered some current examples and results of tree-bridges and sought input from the broader audience on ideas for additional measures. Biographical Sketch: Hans Bekker is engineer of the Agricultural University of Wageningen and is working at the Road and Hydraulic Engineering Institute (DWW), an inside advisory unit of the Ministry of Transport, Public Works and Water Management. He works as program leader mainly with wildlife, roads, and traffic and functions as a liaison between civil engineers and ecologists. He was chair of the European project COST 341: Habitat Fragmentation due to Transport Infrastructure. He is program leader for the Dutch Long Term De-fragmentation Program. He is member of the Steering Committee of the International Conferences on Ecology & Transport (ICOET), as representative of the Infra Eco Network Europe (IENE).