video: Three North American river otters are seen frolicking in the snow on the docks at the Smithsonian Environmental Research Center, caught on video using the center’s night-vision wildlife cameras. Courtesy: Karen McDonald, Smithsonian Environmental Research Center North American river otters aren't known for cleanliness—often eating, playing, and relieving themselves in the same areas. However, this less-than-ideal hygiene has a silver lining. Researchers say these habits can offer