Giant river otters (Pteronura brasiliensis) are indigenous to South America and are the largest animal in the weasel family. They are social and like to defend their territory along bodies of water like riverbanks. One study explored their behavior in Brazil and found that they spent most of their time fishing and entered their dens around 4:00pm, mostly exiting the den at night to defecate or catch prey that is nearby.

Photo by Alycia Drwencke, Edited by Isabelle McDonald

Reference:

Leuchtenberger, C., Zucco, C. A., Ribas, C., Magnusson, W., & Mourão, G. (2014). Activity patterns of giant otters recorded by telemetry and camera traps. Ethology Ecology & Evolution, 26(1), 19-28.