Oswald, P., L. Schulte, B. Tunnat & B. A. Caspers

Population monitoring of European fire salamanders (Salamandra salamandra) with a new photo-recognition software. pp. 179-197 plus Supplementary material.

Abstract. Population monitoring is a crucial method for conservation projects, especially for the highly endangered clade of amphibians which is threatened by habitat loss and emerging infectious diseases such as the chytrid fungus Batracho­chytrium salamandrivorans (Bsal). Bsal has led to massive population declines of European fire salamanders in Belgium, the Netherlands and parts of Germany and population trends are decreasing. Thus, regular population monitoring is essential to keep track of population dynamics and detect potential Bsal outbreaks, especially since valid population estimates for many species and/or populations are scarce. In recent years, photographic mark-recapture studies have gained importance enabling researchers to keep track of individuals without the use of harmful marking techniques that might influence behaviour or survival. We monitored a European fire salamander population over four years in the Kottenforst forest, Germany, by combining a mark-recapture approach with a new photo-recognition software, the Amphibian and Reptile Wildbook. We investigated potential differences of two ecotypes, i.e., larval populations bred in ponds and streams. Furthermore, we compared the observed number of larvae and the estimated population sizes between two consecutive years. There was a year effect on the observed number of larvae, the percentage of injured larva and estimated population size. The habitat type affected apparent survival rates. There was also a habitat effect on the percentage of injured larvae, but this was only existent in some years. The mean larval size, water temperature and the superpopulation size were not affected by any of the aforementioned factors. Although the population was free from Bsal, the high variation in the population estimates emphasize the need for a regular and standardised monitoring to assess the current population status and detect early population declines that might otherwise remain overlooked.

Key words. Amphibian and Reptile Wildbook, Caudata, conservation, individual growth rates, individual recognition, photographic mark-recapture.