Coypus (Myocastor coypus) in Flanders: how urgent is their control?

In Flanders populations of the coypu (Myocastor coypus) are present in the Grensmaas valley and in the surroundings of Hasselt-Zonhoven. Incidental observations have been reported from other parts of Flanders. The number of coypus in Flanders and surrounding countries has increased over the last few years and, in response, a control campaign was conducted by trappers of the Flemish government and of the province of Limburg in March-April 2002. The aim of the campaign was to assess the feasibility of eradicating the coypu in Flanders. Two types of trap were employed: Conibear 160 traps and live trapping cages. The live trapping cages had a lower trapping success than Conibear 160 traps, due to the late start of the campaign. These cages also contained more unintended captures, but these animals could be released back to the wild, in contrast with the Conibear 160 traps, which kill the animals. There was no difference between the number of coypus entering the Conibear 160 traps from inside or outside their burrows. Hence closing the traps from the outside, which would reduce the risk of unintended captures, would also considerably decrease trapping probability. Coypus of all ages were captured, the oldest being 11 years. No sex or age differences were found between coypus caught in the two types of trap. Females were found to be reproductive 3-6 months after birth and males after 6-12 months. These data should be handled with caution, as they cover only a very short sampling period. In January 2003 the campaign was repeated. The ultimate aim of this control campaign is to fully eradicate the coypu in Flanders, so that in the future only control at the borders will be necessary.