While similar to their more mundane brethren, blue otters were larger and had flattened tails with sharp crests on each edge. They generally traveled in small groups during the day, feeding on fish, eggs, smaller aquatic mammals, and birds. Using tree roots as structural supports, they resided in dens cut into larger, stabler sandbars or riverbanks. Here they produced litters of only one or two young each year. Their breeding pattern, coupled with their large profile and valuable pelts, made them ideal targets for extinction. It was not surprising then, that blue otters were endangered. In many areas of northwestern Middle-earth (notably Gondor), however, they were protected by hunting bans.