Estimating reproductive success of primates and other animals with long and incompletely known reproductive life spans.

Abstract

Lifetime reproductive success is difficult to obtain for adequate numbers of wild, long-lived animals because of incomplete knowledge of reproductive life histories and fates of offspring. A procedure is described that provides a standard estimate of lifetime reproductive success from either complete or incomplete reproductive life spans. For this procedure, reproductive success is defined as the following ratio: the number of offspring living to a criterion age in a given time period divided by the number expected for that age and period. The number expected is based upon the mean inter-birth interval of the population, the length of the time period, the age criterion of reproductive success chosen by the researcher (e.g., the average age of menarche), and the probability that an offspring will live to the criterion age. The effect of error upon the estimation of parameters is analyzed using the yellow baboons of Mikumi National Park as an example. The method can be used for both sexes, any litter (clutch) size, any mating system, any mean length of interbirth interval, any age criterion of reproductive success, and any study length that allows a reasonably sized sample of individuals for each of whom a substantial proportion of their reproductive life span is known. © 1992 Wiley-Liss, Inc.