Uinta ground squirrel demography: is body mass a better categorical variable than age?

Abstract

Compared the relative impact of age and body mass on fecundity and survival in a population of Spermophilus armatus and modeled the population using body mass classes as stage categories in Lefkovitch stage transition matrices. Body mass was a better predictor of survival than age, and was nearly as good a predictor of litter size. Larger and subsequently more fecund young were a consequence of a population reduction.-from Authors