Advisor: Günter Gollmann

Master's Defensio - Tuesday, June 20th 2021, 14:00, UBB, Seminarraum 5.1

Abstract

The dynamics of two populations of the European fire-bellied toad, Bombina bombina, in the Danube River floodplains of Lobau, Austria, were studied over a period of eight years, from 2015 to 2022. The habitats of the two populations, Seeschlacht and Königshaufen, are characterized by contrasting environmental conditions: Seeschlacht is located behind the Danube flood dike and water levels are relatively stable, while Königshaufen is located on the river side of the dike, resulting in a more dynamic water regime, with strong intra- and interannual changes in water levels. Software supported image identification of photos of fire-bellied toads was used to establish a database and create the capture history of all animals that had been captured and released over the studied period. Capture-recapture models were applied to estimate capture probability, apparent survival, per capita recruitment, and the population size of each population separately. Apparent survival was higher in the more stable Seeschlacht area, while per capita recruitment of adults was higher in the more dynamic Königshaufen area. The population of Königshaufen has witnessed a large drop in 2019, most likely because of unsuccessful reproduction during the previous year, but has been increasing again since then. The population of Seeschlacht was relatively stable but has shown a downwards trend
between 2017 and 2022 which may be the result of unfavourable environmental conditions for reproduction in this area.