THE DYNAMICS OF AGE-STRUCTURED POPULATIONS WITH A GESTATION PERIOD - DENSITY-INDEPENDENT GROWTH AND EGG RATIO METHODS FOR ESTIMATING THE BIRTH-RATE

We pose and analyze a new demographic model which includes embryo abundance and a gestation period. All vital rates are fully age-dependent but do not depend on population density. We demonstrate convergence to a stable age configuration, characterize that configuration, and derive expressions for important population attributes such as the Malthusian parameter and net reproductive rate. We then use the model in two ways. First we examine effects of a gestation period on the population growth rate and the nature of population waves. Then we deduce a variety of simple birth rate estimators which can be applied to field populations. These include nearly all the existing egg ratio methods, and several new ones, as well. © 1991.