We used cohort analysis to evaluate temporal variation in the population density of white-tailed deer (Odocoileus virginianus) at the Canonto Study Area in southeastern Ontario. During continuous study between 1953 and 1986, the population underwent 2 major fluctuations in density, ranging between 1.3 and 7.0 deer/km2. Variation in instantaneous exploitation rates was related linearly to hunting effort, as predicted by the simple random search model used in cohort analysis. Temporal variation in the annual rate of increase of the deer population was largely accounted for by variations in hunting effort and the per capita rate of recruitment. Recruitment rates and growth rates of juveniles showed evidence of delayed, rather than immediate, response to changes in population density. Dynamic interactions between deer and their food supply probably caused similar time lags in both growth and recruitment rates. Such time lags are likely to predispose the population to oscillations, and this tendency was possibly exacerbated by temporal variation in exploitation effort.