Comparative demography of new world populations of thrushes (Turdus spp.): Comment

Survival and fecundity are fundamental to the study of evolutionary ecology, as they are two of the key variables influencing the constrained optimization process we call natural selection. Likewise, population managers require accurate estimates of these parameters; along with dispersal, they govern population dynamics (Lack 1954) and thus are essential for predicting population change and the effects of management actions. It can be frustrating, then, when survival is difficult to estimate for certain populations, as in some avian species that exhibit a substantial degree of dispersal.