Publications

Two inventories of amphibian breeding sites from the years 1978/79 and 1991/92 have provided a rich source of data on spadai distribution and population sizes. Several endangered amphibian species in the canton of Aargau show an alarming decline. It is evident that efforts to protect the breeding sites or to create new sites have been insufficient to compensate for the loss of habitats.

In the canton of Aargau (Northern Switzerland) an inventory of amphibian breeding sites, covering the whole territory, has been made in 1978/79. Altogether 918 waters were entered on a map, amongst them 94 brooks. The same inventory was repeated In 1991192 by much more collaborators who ascertained the amphibian stocks of 2267 waters, 919 of them being brooks. A comparison of the two inventories shows that in the time between 111 sites were destroyed and 141 spoilt, while 656 grounds remained unchanged and 331 new sites were created.

Amphibians often cross roads when migrating in the course of a year. In the canton of Aargau 86 such migrating sites are known. Between 1989 and 1998 twelve of them have been watched, whereby altogether about 187 000 Rana temporaria, 90 000 Bufo bufo and 19 000 newts (mostly Triturus alpestris) have been registered and the data evaluated. It was between February 24 and April 12 that 90 % of all the amphibians watched migrated to their breeding grounds.