The number of species recorded on Red Lists in Central European countries is high and includes several species that already have disappeared. This suggests that the total species number is declining in these countries. However, besides disappearing species there are species immigrating into new areas, either due to human help or due to natural area expansion, as well as formerly extinct species that are remigrating. Regional extinction of some species therefore does not necessarily lead to a decrease in total species number. The study analysed the influence of extincion and of immigration on total species number in Switzerland for the last 107 years and for several taxonomic groups (mammals without bats, breeding birds, reptiles, amphibians, fish, cyclostomes, butterflies, grashoppers and dragonflies). During this period total species number clearly increased (+ 19 species). This increase is mainly due to species that immigrated autonomously from other European countries. Most of them are wetland inhabitants.
Martinez, N., Küttel, M., & Weber, D. (2009). Deutliche Zunahme wildlebener Tierarten in der Schweiz seit 1900. Naturschutz und Landschaftsplanung 41(12): 375-381.
