Comparing life expectancy of three deer species between captive and wild populations

Life in zoological gardens provides a number of benefits to captive animals, resulting in an artificial reduction of the “struggle for life” compared to their free-ranging counterparts. These advantages should result in a higher chance of surviving from 1 year to the next, and thus in longer average life expectancies for captive animals, given that the biological requirements of the species are adequately met. Here, we compare the life expectancy of captive and free-ranging populations of three deer species (reindeer Rangifer tarandus, red deer Cervus elaphus, and roe deer Capreolus capreolus). Whereas captive reindeer and red deer had life expectancies equal to or longer than free-ranging individuals, the life expectancy of captive roe deer was shorter than that of free-ranging animals. These results support the impression that roe deer are difficult to keep in zoos, whereas reindeer and red deer perform well under human care. We suggest that the mean life expectancy of captive populations relative to that of corresponding free-ranging populations is a reliable indicator to evaluate the husbandry success of a species in captivity.