Estimating the demographics of an ocellated lizard (Timon lepidus Daudin, 1802) population through photo identification capture-recapture

Abstract

This study used photo identification “ capturerecapture” to monitor a population of ocellated lizards (Timon lepidus Daudin, 1802), providing the first data on the demography of this species in the wild. The monitoring was conducted over a period of six years in a valley of the Var River in southeast France, with an average rate of 25 visits per year. This resulted in 1870 exploitable photographs that allowed the identification of 138 different individuals along a 1,600m linear path. For the 114 lizards that were over the age of one, the life history data was analysed with MARK software using the Cormack-Jolly-Seber (CJS) model. This analysis enabled survival estimates – both annual and seasonal (mid-May to end of September versus October to mid-May) – for both sexes. Annual survival appears to be higher in males than in females (0.65 versus 0.48), with a life expectancy of 2.3 years for adult/ subadult males and 1.4 years for adult/ subadult females. During the winter period, monthly survival is close to 1 for both sexes. It is lower during the summer period : 0.92 in males and 0.87 in females. These survival and longevity rates are surprisingly low for a species of this size. However, they can be considered reliable given the high “ recapture” (via photo identification) rates (between 0.465 ± 0.053 and 0.986 ± 0.014 in spring, lower in autumn) and the isolation of the study site.