Estimating the transition of individuals between life stages

Over their lifetimes, individuals of a species transition from one stage of their life cycle to the next (for example, a nonreproductive juvenile will mature to a reproductive adult). Estimating the age at which these transitions occur can be complex for a variety of reasons. A fundamental, generalizable way to assess the mean age of transition along with a standard deviation of the distribution of the transition is developed. We propose and statistically develop a method that is easy to use, requires only one data collection period, and provides reliable estimates for the mean and the standard deviation of the transition point. Our results for the case studies for one species, Carnegiea gigantea , using eight independent real‐world datasets, are robust, confirming the validity and usefulness of the proposed technique. We develop an important ecological metric that quantifies the age at which a species transitions from one stage to another in its life cycle. This is a basic ecological metric that is often assumed, but that until now has been difficult to quantify practically for many species. This metric is easy to use (we provide a spreadsheet that does all the calculations) and essential for all life scientists, regardless of species, life form, or ecosystem of study. Copyright © 2015 John Wiley & Sons, Ltd.