While the number of captured muskrats is increasing again in many places in the Netherlands, a downward trend has been visible in West Brabant for years. Yet muskrat catchers like Jeroen van Heijst are no less alert. “As long as the muskrat is not at zero, we have not won the match.”
In Brabant, 17 percent more muskrats were caught last year than the year before, and nationally even 27 percent. The animals pose a threat to dikes and banks. They dig caves under water, make barriers porous and thus increase the risk of subsidence and breaches.
In the working area of the Brabantse Delta water board, between Bergen op Zoom and Tilburg, the picture is more positive. Catch figures have been declining there since 2020. “In West Brabant we have made approximately 400 catches, while in the whole of Brabant there are approximately 2,600,” says André Bosters of Brabantse Delta. South West TV.
“It is becoming increasingly difficult to filter out those last few rats.”
One of the people who stands in the ditch every day with his boots is muskrat catcher Jeroen van Heijst. In some places his catch has been at zero for two to three years. “But then you have to stay alert,” he emphasizes. “It is becoming increasingly difficult to filter out the latter in an area with only a few rats.”
How quickly things can go wrong is evident from a field trial in which muskrats were not controlled for three years. “We started with a small population of twenty to thirty animals. After three years there were more than a thousand. The growth is really explosive.”
The problem lies beneath the surface of the water. “Muskrats always dig their burrows under water,” says Van Heijst. “As a result, you do not immediately see the damage, but it does create a dangerous, porous spot in a dike.” This is not only a risk for water safety, but also for farmers and recreationists. “I have seen hikers completely sink into a muskrat hole. And you can also end up in such a hole with a horse or car.”
To ensure that areas are truly free of muskrats, the water board is increasingly using DNA testing. Water samples are examined in the lab for traces of muskrat DNA. “If we don’t find anything, we don’t have to check as intensively there,” says André Bosters.
Van Heijst calls it a valuable addition, but emphasizes that fieldwork remains necessary. “You can stand on the side of the ditch with ten laptops, but ultimately you have to do it in practice.”
“The protected beaver makes catching muskrats more complicated.”
Meanwhile, the work is not getting any easier. Due to higher water levels and adjusted mowing policy, traces of muskrats are more difficult to see. And the beaver doesn’t make the job any easier either.
“The beaver is beautiful, but makes enormous dens,” says Van Heijst about the animal, which weighs up to thirty kilos, compared to the one and a half kilos that a muskrat weighs. “Muskrats sometimes just live there. And because the beaver is protected, catching muskrats there becomes more complicated.”
