Long-term studies are subject to stochastic forces as well as deterministic, ecological differences. We illustrate this by means of Polya’s urn scheme and two examples based on our long-term study of the behavioral ecology of the acorn woodpecker (Melanerpes formicivorus). In both cases, the years during which the study was conducted had a large, apparently stochastic influence on population dynamics. Despite such variability, long-term studies offer several notable benefits, including the opportunity to gain a more nuanced understanding of a particular system and the ability to incorporate technological and theoretical advances. Ultimately, it is with long-term data that we can hope to disentangle and understand the stochastic and deterministic factors that drive ecological systems.