River management and habitat characteristics of three sympatric aquatic rodents: common muskrat, coypu and European beaver

The ecological environment of three aquatic rodents was studied in the French Ardennes region. Two species, the coypu ( Myocastor coypus ) and the common muskrat ( Ondatra zibethicus ), are invasive. By contrast the native European beaver ( Castor fiber ) was extirpated from the region, subsequently reintroduced, and currently is protected. The aim of this study was to compare the ecological requirements of these three species and predict their future range distributions. We studied the relationship between the species and describe the characteristics of waterways and riparian vegetation in 29 sampling sites. Coypus and muskrats were observed in a variety of riparian habitats and their probability of detection appeared to be independent of waterway width, bank height or bank slope. The availability of numerous herbaceous plants, known to be consumed by these species, may facilitate their settlement. Muskrats are widespread on the French Ardennes waterways, but coypus have not yet colonised the northern part of the region. On the other hand, the beaver was observed primarily in the widest waterways with high banks, where woody plant species, such as Betula , Carpinus and Fraxinus , are found in abundance. Potentially favourable sites for beaver and coypu settlement were analysed to suggest appropriate management according to each species’ status. However, the number of sample sites is weak, especially for sites with beaver, limiting our conclusion.