Validation of gum-line recession as a reliable technique to age tigers

Abstract

Like other members of the Panthera genus, tigers are threatened throughout their range. Given their conservation status research focused on their population dynamics in the wild is needed, including population growth, lifespan, and breeding success, which requires reliable estimates of age. Current techniques to estimate age in tigers are either not reliable and/or difficult to apply in the field. Gum-line recession accurately estimates age for mountain lions, but has never been tested for tigers. The goal of this study was to determine whether gum-line recession of the upper canine teeth is a reliable indicator of age in tigers and if so, to define the equation that enables age estimation. We measured gum-line recession in 12 individuals of known ages and performed linear regression analysis to investigate the validity of this technique for tigers. We found a strong relationship between gum-line recession and age, where the model provided reliable age estimates for animals within 1-year age classes in 10 out of 12 tigers measured, providing increased accuracy over current methods.