Estimating Population Sizes, Viability and Sensitivity of the Crested Newt (Triturus cristatus) at a Landscape Scale

Population sizes, viability and sensitivity of the threatened amphibian crested newt (Triturus cristatus) were estimated in an area of 144 km2 in southeastern Sweden. Eighteen ponds were monitored during spring and summer 2004 using drift fence with pitfall traps, funnel traps, visual observation and netting. Estimated adult population sizes ranged between 0 and 620 individuals, and the mean (±SD) in local populations was 297 ±233 individuals. Viability with and without management, and sensitivity of different parameters were simulated with a demographically and spatially structured stochastic model. Due to uncertain data, the model was simulated with parameter ranges to estimate upper and lower bounds of viability.