Lutz Dalbeck1, Beatrice Lüscher2, Dagmar Ohlhoff3
12Biologische Station im Kreis Düren e.V., Zerkaller Str. 5, D-52385 Nideggen, Germany;, Email: [email protected] 2-KARCH, Swiss amphibian and reptile conservation pro-gramme, Natural History Museum of Berne, Berna-strasse 15, CH-3005, Berne, Switzerland
33Biologische Station im Kreis Düren e.V., Zerkaller Str. 5, D-52385 Nideggen, Germany
Tóm tắt
Abstract
The Eurasian beaver Castor fiber, formerly occurred across the Palaearctic,
but was nearly eradicated in the 19th century. Due to reintroductions in the
20th century, beaver populations are increasing and now extend into highland
areas. Natural still waters are scarce in highlands of Central Europe.
Therefore the question arises, “Are beaver ponds essential habitats for
amphibians?”, especially since fishes, predators of amphibian larval stages,
also inhabit beaver ponds. We investigated the amphibian fauna of one
typical valley in the Eifel, that was colonized by beavers in 1981, and
compared areas with and without beaver ponds. All anuran species of the
region occupied beaver ponds, including species that were absent (Alytes
obstetricans, Bufo bufo and Rana kl. esculenta) or rare (Rana temporaria) in
natural waters. Alytes obstetricans obviously benefited from pond
construction and the removal of trees by beavers which leads to sunny plots
along the slopes of the valley, crucial habitat for this species. The
urodelans Salamandra salamandra, Triturus alpestris and Triturus helveticus
were widely distributed in beaver ponds. Our results show clearly, that
beaver altered landscapes offer high quality habitats for amphibians in our
study area. Due to a considerable increase of habitat heterogeneity in
impounded streams, the predator Salmo trutta was not able to extirpate the
amphibian fauna. We conclude that the historic effects of beavers need to be
considered for a proper understanding of patterns of amphibian distribution
and habitat requirements in Central European Highlands. Furthermore,
beaver-created landscapes will be of future relevance for conservation of
endangered species, like Alytes obstetricans.
