The raccoon (Procyon lotor) arrived in Europe from North America more than 50 years ago and is listed as an 'invasive exotic species'. For several years, there have been signs of population formation in Limburg with frequent reports of raccoons from the area near Sittard and Maastricht. Under the 'European Union Invasive Exotic Species List' (Regulation No 1143/2014), the Province of Limburg is obliged to remove raccoons from the wild if there are signs of population formation. The Province of Limburg asked the Mammal Society to coordinate the 'Raccoons in Limburg' project and to work closely with Bionet Natuuronderzoek, Water Board Limburg, AAP Foundation, FBE Limburg and RIVM for implementation of the project.
The project aimed to gain knowledge about raccoon trapping, set up an online notification portal and evaluate the effectiveness of trapping. Trapped raccoons were taken in by AAP Foundation in Almere. Shooting raccoons was possible under strict conditions, but no raccoons were shot during the project.
It appeared that raccoons (now) live throughout the province of Limburg. A genetic analysis using DNA samples from raccoons trapped or found dead in Limburg was carried out by RIVM in collaboration with the Natural History Museum of Luxembourg. A previous study with a limited set of samples showed that the population in the core area near Sittard is genetically different from other (European) populations and (thus) of regional origin. The population around Sittard forms one entity with the population of raccoons near Gangelt, Germany, located in the state of North Rhine-Westphalia. It is not yet known whether the raccoons caught in the Geul and Meuse valleys are genetically related to the population in the Ardennes (Wallonia) or genetically related to the population around Sittard/Gangelt. In Limburg, there is (yet) no immigration from the established raccoon population in central Germany, as its front lies halfway of North Rhine-Westphalia.
Trapping raccoons was successful in the core areas (Valley of the Roode Beek, Geleenbeek valley, Geul valley and around Maastricht). A total of 95 raccoons were trapped, but this did not result into the complete disappearance of the population in Limburg.
RIVM, in collaboration with AAP Foundation, investigated how many of the trapped raccoons were infected with raccoon roundworm (Baylisascaris procyonis). Of these raccoons, 52% of the animals were found to be infected with this roundworm.
Italian research shows that it is possible to completely eliminate a local population of raccoons, provided control is maintained for a longer period of time: at least several years. In Limburg, there are several cross-border populations. This makes it difficult to sustainably reduce the numbers of raccoons present in Limburg if intervention is only done in Limburg. Due to the continuous exchange with and/or immigration of raccoons from adjacent areas, coordinated cross-border control is needed to keep the population and densities at low levels. This requires intensive cooperation and consultation with neighboring countries. The Province of Limburg has been in contact with the relevant foreign authorities and asked for appropriate control to prevent migration to the Netherlands. This has not yet led to noticeably fewer catches in Limburg.
If raccoon trapping in Limburg is not continued, it is inevitable that raccoon numbers will increase sharply in the coming years. This is expected to result in much more perceived nuisance by citizens and many more complaints about the presence of raccoons. There is little or no way to prevent this nuisance, which requires much more than reinforcing hen houses or properly storing of rubbish. Raccoons are smart and strong animals that are difficult to keep out. The increase in raccoons will also lead to increasing damage and predation of vulnerable wildlife (including rare breeding birds, amphibians, small mammals
and hibernating bats).