Advisor: Günter Gollmann
Master's Defensio - Friday, June 28th 2024, 9:00
Seminar Room 1.2, UBB, Djerassiplatz 1, 1030 Vienna
Abstract
Amphibians are the worlds most threatened animal group. Loss of habitat is one of the main reasons for the decline. In Austria, the European Green Toad (Bufotes viridis) well-known in urban areas, is one of these endangered species. The study area Donaufeld is big and open with fields, but a big urban expansion with residential buildings is planned there. The transformation of their habitat Donaufeld in Vienna poses a potential threat to the Green Toad population there.
The present study is a capture-recapture study on the current Green Toad population in the Donaufeld. Data were collected during the breeding season (March until July) of 2023 and include sex, body mass, snout-vent-length of captured toads. The toads were captured, measured, photographed and released again after data collection. For population analysis the Jolly-Seber-Schwarz-Arnason (JSSA) model for open populations was used.
96 individual toads (66 males, 30 females) were captured during this study The males were in average lighter and smaller than females but the SMI suggests no difference in body condition of the sexes. Overall B. viridis in the Donaufeld show a comparably high body condition in comparison to toads of other Viennese populations. The calculated population size of 2023 in the Donaufeld with 172 individuals (CI: 128 – 232) is smaller than calculations of 2021 and 2022, suggesting a decline. The apparent survival rate Phi was lowest from 2022 to 2023.
The high SMI and recapture rate also indicate a well-established population with mature, healthy toads. The Donaufeld apparently provides an optimal habitat for the European Green Toad, resulting in good body condition when compared to other Viennese populations. Nevertheless, the population size is likely decreasing, probably partly due to the ongoing construction work. As the habitat Donaufeld is changing, the question remains if this population of Green Toads will be able to adapt.
In conclusion, this study underscores the importance of continued monitoring and conservation efforts on the Donaufeld Green Toad population to ensure its long-term survival.
Key words: urban habitat, Bufonidae, population monitoring, demographic analysis
