Although a male and female may pair for several months during the breeding season, there is no strong pair bond between them and the male is dominant during their temporary associations. Play serves to reinforce social bonds, so important to social otters, but also helps young otters perfect their hunting and fighting techniques. Otters are very vocal, with a large repertoire of calls. Different vocalizations readily distinguish Lutra from Lutrogale and both of these from Aonyx. Differences in vocalization are to be found mainly in these contact , summons and greeting calls, but similarities, especially in threat and alarm calls, remain.
Scent marking is a common feature of otter behavior.
Only the exclusively marine Sea otter lacks the paired scent glands at the base of the tail which give otters their heavy, musky smell. Scent marking delineates territorial boundaries and communicates information concerning identity, sex, sexual state, receptivity and time elapsed between scenting visits. A pair or a group may clear and scent mark a site together during a bout of feverish activity which leaves an area denuded of vegetation, smelling of scent, feces and urine. The strong, dank odor can be detected near any site which has been visited within the previous several weeks. For a few days the smell is overpowering, but by a week later it is pleasant.