Jan Gouwy

As a non-native species, the raccoon (Procyon lotor) has been present in the wild in Europe for about a century, and the expectation seemed justified that it would establish itself also in Belgium. A meticulous recording and interpretation of all possible raccoon sightings in Flanders (northern Belgium) over the past 30 years shows that this was not the case during the first two decades of this period. In contrast, a clear increase in the number of registrations has occurred in the last decade. Necropsy of collected roadkills also shows that reproduction in the wild is occurring throughout the region, a finding confirmed by the increasing use of camera traps. The raccoon has been included in the Union List of Non-Native Species of Concern since 2016 through the EU Regulation, and addressing its further population development in Europe is currently the subject of international consultations. This study aims to provide a documented baseline for Flanders on the raccoon population status, while also making some considerations regarding the need for systematic intervention.

Medium‐sized carnivores, including the synanthropic stone marten (Martes foina Erxleben, 1777), have shown remarkable adaptability to urbanised and fragmented landscapes, facilitating their spread across mainland Europe. This study investigates the recolonisation of a highly urbanised region by stone martens within two decades, examining spatial and temporal genome‐wide data (using genotyping by sequencing) to reveal colonisation dynamics, sources, and barriers influencing their expansion. Using genotypes from 5536 SNPs across 376 stone martens collected between 1995 and 2013, our findings indicate that stone martens successfully expanded through urban environments, yet dispersal was neither entirely random nor strictly distance‐dependent. The initial southeastern stronghold (E1) showed the lowest genetic diversity and limited spatial expansion, while other population sources contributed to recolonisation, highlighting a complex, multi‐source expansion. Gene flow in the early stages was largely confined to E1, progressing northward and eventually enabling exchange with a second eastern lineage (E2). Meanwhile, the western lineage displayed higher connectivity, occasionally crossing barriers like motorways. Motorways, however, significantly shaped recolonisation patterns, reducing gene flow, while other elements such as built‐up areas, secondary roads or waterways showed an additional though very small effect. Over the study period, genetic patch size increased, indicating longer dispersal distances. Gene flow strengthened within both eastern (E1 and E2) and western populations. Still, the western population diverged into two subclusters (W1 and W2) of which one became more differentiated. This suggests limited genetic homogenisation in the near future. This study provides insights into the genetic and ecological dynamics of carnivore recolonisation in highly fragmented landscapes.

Ecosystem services are the contributions that natural ecosystems make to people. Mammalian carnivores can provide both positive and negative ecosystem services by consuming pest or game species, respectively. In this study, we determined the consumption of certain game and pest species for a guild of sympatric small- and medium-sized carnivores (European badger, red fox, European polecat, stone marten, stoat and least weasel). We found that game and pest species comprise a notable proportion of the diet, ranging from 0.0% to 12.6% and from 2.7% to 46.3%, respectively. Furthermore, for all carnivores we found that the proportion of pest species such as rats and voles (i.e., positive ecosystem service) was higher than the proportion of game species such as pheasants, partridges and hares, i.e., negative ecosystem service). Moreover, stoat and weasel did not consume any game species. This study gives a first overview of the potential ecosystem services through consumption of pest and game species provided by small- and medium-sized carnivores.