Stability and annual return rates in amphibian populations

Amphibians are declining worldwide and different ecological traits, such as population growth rate and demographic stochasticity have been associated with their risk of extinction. However the population annual return rate, a parameter that gives information on the rapidity at which a population returns to equilibrium after an external perturbation, has never been analysed. In this study the annual return rates of 21 amphibian time series, belonging to 16 species, were estimated through non-linear (theta) logistic modelling. Annual return rates of salamanders (0.73) did not differ from those of frogs (0.79) and all return rate values were below the threshold for chaos. These results show that, in general, amphibian populations are regulated and do not differ in their dynamics from other vertebrate taxa.