Age characteristics of a deer herd

White-tails have an average life span of 8 years, but most do not live beyond 4 to 5 years of age. Captive animals have lived nearly 20 years.

Reproduction adds animals to a population while mortality removes them. If these elements are out of balance, the total number of deer increases or decreases as a result. Even when mortality and reproduction are approximately in balance the composition of deer population changes as animals grow old and are replaced by younger ones.

Three types of measurements are used to describe population changes-population size, sex ratio and age distribution. The relative size of age groups, by sex, can give some insight into the impact of hunting on a herd of deer.