7 - Estimating the Rate of Population Change

Abstract

An array of methods is available to investigators to estimate the finite and instantaneous rates of population change. Different statistical approaches may need to be used to estimate intrinsic and realized rates of population change. Some methods are better suited for estimating one parameter or the other. Similarly, some analytical approaches are better for estimating the annual or finite rate of population change, other methods are better suited for estimating the instantaneous rate of change. These methods are generally based on geometric or exponential growth assumptions. The intrinsic rates of change are estimated by these exponential-based growth models when a population is indeed in the exponential growth phase. Alternatively, when a population is experiencing density-dependent growth, the exponential-based methods can only be used to estimate the realized rate of change over short periods of time. Nevertheless, the assumption of exponential growth will eventually be violated. In situations in which a series of abundance surveys exist during density-dependent growth, the ratio method can be expected to provide a better measure of average performance than exponential regression-based methods.