If you see a furry head with whiskers pop up in a local creek or wetland, it may be an otter. Or it may be a beaver.River otters were re-introduced to Western New York in the late 1990s after they ...

To add to Alaina Mencinger’s excellent article (“Beavers, acequias and New Mexico’s watersheds,” June 6): Beaver dams don’t just recharge groundwater and create habitat for birds — they also help ...

North American river otters eat, play and defecate in the same place. And their unhealthy habits make them ideal for detecting future health threats in the environment. Kristen Goodhue A North ...

A North American river otter (Lontra canadensis) wanders through a forest at the Smithsonian Environmental Research Center. Credit: Calli Wise, Smithsonian Environmental Research Center YouTube video: ...