Between-individual variation in phenotypes within a population is the basis of evolution. However, evolutionary and behavioural ecologists have mainly focused on estimating between-individual variance in mean trait and neglected variation in within-individual variance, or predictability of a trait.

These data continue and expand upon data collected by Kenneth B. Armitage titled, " Social Behavior and Population Dynamics of Yellow-bellied Marmots", that goes from 1965 - 2001. A record includes the subject's age, sex, body mass, locality, and reproductive status. Starting in 2002, additional col