Throughout their range, the North American River Otter (Lontra canadensis), Common Muskrat (Ondatra zibethicus) and North American Beaver (Castor canadensis), have been exploited for their fur for centuries, leading to local-scale extirpations. More recently, these species have begun to return to landscapes where they have been absent since the commercial fur trade. The reappearance of these species in human-dominated, heavily-altered landscapes merits attention both for conservation science and potential ecosystem services. In particular, these species have begun to reappear throughout urban waterways in some of the most densely populated cities in North America, particularly in Chicago, Illinois (USA). This review examines the ecology of these species, their historical interactions with humans, and synthesizes the available case study data that assesses their occurrence in urban areas. These urban landscape appearances also facilitate discussion on human conflict mitigation and potential conservation practices moving forward. We highlight the need for continual population surveys of these animals, to both better understand how semi-aquatic mammal populations cope in such human-altered landscapes and anticipate their activities when city planning. Additionally, this review emphasizes the benefit of urban green spaces and offers practical solutions, with examples like floating wetlands, which serve an ecological function both for humanity and wildlife. The occurrence of these species in our urban waterways may be an indication of their adaptability, or conversely, a sign of how little natural wetland and riparian habitat remains for them. Research is underway, and more is needed, to better answer this question.
Clark et al. (Mon,) studied this question.