Analyse de la dynamique des populations de ratons laveurs (Procyon lotor) en Wallonie et estimation des densités de population dans deux massifs forestiers par pièges photographiques

Abstract

As an invasive species, raccoons (Procyon lotor) present explosive population dynamics on a European scale, which worries scientists and natural areas managers with regard to the potential dangers they represent for native biodiversity and the "man-wildlife" conflicts they can provoke. In Wallonia, their presence has been proven since the early 2000s and observations have been increasing since 2010, but their population level remains unknown. This work first seeks to establish the population dynamics of the species in southern Wallonia (Belgium) by analyzing nocturnal abundance indices (INA) between 2010 and 2018. Its second objective is to estimate the population densities in two forested areas using camera traps, by applying the "Random Encounter Model (REM)". The INA, multiplied by 5 between 2010 and 2018, increases significantly over time at the scale of the 19 hunting councils in which raccoons have been observed. However, the method lacks precision due to the low detectability of the species during night counts and, even if the increasing trend is confirmed, the rate of expansion remains uncertain. This is especially true if data are analyzed individually by council as the number of observations is often too small and the biases too large. The REM, applied for the first time to this species, gives estimates of population densities of 2.26 - 4.22 individuals/100ha in Gaume and 2.12 - 3.39 in the Saint-Michel Freyr massif. Although subject to numerous biases, the REM is proving to be an interesting tool and allows plausible densities to be obtained, but points of comparison are currently lacking for evaluating its reliability.