No abstract

Photo-identification is a non-invasive method used for recognising wild animals with distinctive and stable patterns over time. This method is now widely used for capture-recapture wildlife monitoring. However, in species exhibiting rapid colouration changes, the evolving body patterns can lead to errors in individual recognition. In this study, we assessed the effect of dorsal physiological colour change of the tiny threatened European leaf-toed gecko (Euleptes europaea) on the performance of Wild-ID and Hotspotter, the two most commonly used individual recognition software for wildlife monitoring. We exposed 30 European leaf-toed geckos to several semi-controlled parameters (substrate type, temperature and light from natural diurnal/nocturnal cycles) in order to characterise the extent of variation in dorsal colouration, by standardised reflectance measurements. The colour of the substrate had a significant effect on individual reflectance changes. Body temperature also seemed to significantly affect the reflectance but the experimental conditions did not allow us to clearly distinguish the effect of temperature and light. For each of the 30 geckos, four photographic databases (n = 4*280) were then analysed by both software packages, under two extreme reflectance conditions. Despite the large changes in individual reflectance, Wild-ID and Hotspotter proved to be extremely reliable with a 100% recognition rate. The analysis of similarity scores suggests that Hotspotter is less sensitive to chromatic variation than Wild-ID. We provide here the first evidence that physiological colour change is not a barrier to computer-assisted individual recognition. This study advocates the use of Hotspotter for monitoring populations of European leaf-toed geckos and other saurians that generate significant colouration change over a short time.

The knowledge of a species’ spatial ecology is essential for its conservation as it helps to implement targeted protection measures to suitable habitats. In 2011 and 2013, two French populations of ocellated lizards Timon lepidus were monitored through very high frequency (VHF) radio telemetry in two distinct Mediterranean habitats: a 77 ha scrubland (n = 8) and a 1590 ha semi-arid steppe (n = 11) corresponding to a heterogeneous and homogeneous habitat respectively. The variability in spatial estimates for the seasonal habitat use of the ocellated lizard was compared within the two sites using the Autocorrelated Kernel Density Estimation (AKDE). Recursive movement patterns and spatial repartition of shelters were further assessed to study the habitat influence on the species’ space use. No significant differences between sexes or sites were identified in the computed AKDE ranges. This inter-site approach demonstrated higher shelter revisits in core-areas than in the rest of estimated home ranges for both sites. A higher shelter density was observed in the core areas of the lizards than in the rest of their home-ranges for the Mediterranean scrubland but not for the semi-arid steppe. Such findings might attest to the species’ adaptive capabilities within two distinct Mediterranean ecosystems.