Monitoring of the presence of Emys orbicularis and of the exotic invasive Trachemys sp. for a conservation biology approach

The European pond turtle, Emys orbicularis (Linnaeus, 1758) is a threatened species throughout Italy, including in the San Rossore estate where I conducted my thesis. One of the main threats to the species is the invasive species Trachemys scripta. In the San Rossore estate, the documented presence of Trachemys has been steadily increasing, as observed in previous thesis works and unpublished data in recent years. One of the goals of this study is to get an updated overview of the presence of Trachemys scripta in the San Rossore estate area. The study was first conducted by repeated counts carried out with binoculars in various areas within the estate. Of these areas we then selected two sites to collect data on the population density of Emys orbicularis in an area with presence of Trachemys scripta (Buca delle Ghiande) compared to one without it (Carbonaie) through capture-marking-recapture method; these data were then used in conjunction with data from previous thesis work to examine how the population density of Emys orbicularis is impacted by the presence of Trachemys. In both areas we placed 10 funnel traps at a fixed distance, without the use of bait; three sessions of three days each were carried out for each site. The captured animals were measured, weighted and marked following standardized procedures and the animals were subsequently released at the same place and day of their capture. The data collected were entered into the software IBM SPSS Statistics 20 and analyzed through a series of statistical tests, like the independent samples t-test. The goals of these analyses were to examine any variation in the data collected between males and females and between the two areas. The estimation of population size in the “Carbonaie” site was calculated using the Lincoln-Petersen method.