Aging cheetahs using gum-line recession and evaluation of expert-based aging techniques

Accurate aging is a useful tool in wildlife management, providing critical information for population dynamics research, age-specific limiting factors, and conservation efforts. Many methods used to age mammalian carnivores are either invasive, expensive, or inconvenient to use in the field. In felids, the gum-line recession has been found to accurately estimate the age of female mountain lions and tigers. In contrast, expert-based aging techniques used on cheetahs (Acinonyx jubatus) can only categorize adults into broad age classes. We assessed whether the gum-line recession of the upper canine teeth provides reliable information for aging cheetahs by using measurements on cheetahs of known age (n = 37) in sex-specific linear models. We found a significant positive relationship between gum-line recession and known age for both female (n = 21) and male cheetahs (n = 16), and we contribute herein sex-specific regression models that can be used to age the animals based on the gum-line measurements collected during handling. In addition, we compared expert-derived age categories assigned to cheetahs of unknown age (n = 23) to the ages estimated by the gum-line recession models. Expert-based aging produced similar results to gum-line recession for some individuals, but the ages of other individuals were underestimated by biologists, particularly for older cheetahs. Our data show that gum-line recession measurements provide biologists with a reliable, minimally invasive, and convenient technique to age cheetahs in the field, and we encourage validation of this technique in other field-intensive projects involving felid capture.