strongest effects on the population growth rate at small population sizes (Leigh 1981; Lande 1993, 1998). Environmental stochasticity refers to stochastic variation that affects all individuals in a certain group similarly and is important both in small and large populations (May 1973; Leigh 1981; Lande 1993). Unfortunately, separating the relative contribution of demographic and environmental stochasticity requires a combination of individual-based data on fitness-variation and accurate long-term time-series on population fluctuations (Sæther & Engen 2002), which are rarely available. Finally, reliable population projections are also dependent on assessment of how uncertainties in the estimates of the parameters affect the accuracy of the population predictions (Ludwig 1996; Sæther et al. 2000; Ellner et al. 2002).