ABSTRACT
Many definitions of sustainable population have been put forward. For a biologist, the simplest and most obvious one is a population of an organism that is within the carrying capacity of that organism's environment, that is, the maximum number of individuals of the organism in question that can be supported indefinitely without degrading the environment's capacity to support future populations. Carrying capacity thus is a function both of the characteristics of the environment—the resources it contains and its productivity—and of the organism—whether it is large or small and how much energy it expends to meet its needs. 1 Many more mice or grasshoppers ordinarily can be supported in a given area than elephants. And even animals of similar sizes may have very different energy needs because of different rates of metabolism; thus, more lizards than birds can be supported in the same area, other things being equal.
