engleski

Population size, survival and viability of the fire salamander (Salamandra salamandra) in Central Croatia

Population viability analysis (PVA) has become a commonly used tool to estimate extinction risk and to model population dynamics of stage-structured populations, such as amphibians. There have been no studies of long-term population dynamics in Croatia. In this study I combined capture-mark-recapture data collected over a 3 year period with population viability analysis. The aim of this study was to analyse data on population size and adult survival of the fire salamander (Salamandra salamandra) and use it to confirm the predictions of population model. Population sizes, annual survival and viability of the fire salamander were estimated in an area of 4, 25 ha in the temperate forest in central Croatia, where 4 permanent plots were installed. Drift fences and pitfall traps were used as sampling technique. Jolly-Seber mark-recapture model was used for the estimation of population density and survival. Data describing survival rates for distinct salamander population, complemented by a literature review on additional demographic parameters, were used to define population matrix and carry out simple viability analysis using a stage-structured model in the RAMAS GIS platform. Estimated population density ranged between 12, 5 and 90 ind. ha-1. The mark-recapture analysis of adult salamanders showed low rates of annual survival of 0, 393. These trends are consistent with simulations of the system, which predicted that studied population had high extinction risk. Estimated quasi-extinction risk within a 50 year period ranged from 88, 2% to 100%. Simulation predicted median time to extinction of 17 years. The PVA model simulation estimated also a negative trend in abundance for the Salamandra salamandra population. These data offers some insight into the likely viability of the study population and suggests a link between local adult survival and salamander population trend. Predictions of PVA can be used as a tool to better understand the demography of amphibian populations.

mark-recapture model; population viability analysis; RAMAS GIS; Salamandra salamandra

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