Communication
Unlike other otter species, Aonyx cinereus are highly social animals. Although they are monogamous (see reproduction), they tend to live in groups of 15-20 otters, (figure 24). With a family so large, communication is very important to their species. They use three different forms of communication, which include vocalizations, scent, and tactile cues.
According to the Smithsonian (n.d.), these otters love to “talk,” and have at least 12 different vocalizations that they use for greetings, summons, alarms, and more. A study by Lemasson et al., (2014, 135) compared 4 different vocalizations for a captive family of small-clawed otters. One functioned as an
Fig. 24. “The National Zoo Welcomes a New Family of Otters,” 2012, May 22. Smithsonian’s National Zoo, 3:01, Retrieved December 4, 2021, from https://youtu.be/9B_4aI4KE1k
alarm, two of them were food-related (food request and possession), and the final one was a contact vocalization. The contact vocalization was the most frequently used throughout the day to maintain group cohesiveness and direction of travel/movements. Much like humans, it appears that individual A. cinereus also carry a uniqueness in their vocalizations. During their study, Lemasson et al., (2013, 277) found that when recorded vocalizations were played, females could discriminate between familiar and unfamiliar males. This distinction could also be made when the females smelled feces, (figure 25).
Fig. 25. Otter Spraint. (Photograph by Myers, P. “Otter Feces,” Animal Diversity Web [2003]. Retrieved December 4, 2021, from https://animaldiversity.org/collections/contributors/phil_myers/ADW_mammals/Carnivora/Mustelidae/otter_feces8929/
Fig. 26. Abscessed Feline Anal Gland. (Image by Unknown. “Feline Anal Gland Diagram,” Glandex [n.d.] Retrieved December 9, 2021, from https://www.glandex.com/pages/cat-anal-gland-info
Across all species of otter, scent is used as a form of communication. This can come in various ways, which include through the expression of the anal glands, or through ‘spraints,’ which are small dollops of feces (Kruuk, 2006). Anal sac gland expression is believed to produce a distinct chemical profile, containing a blend of scent molecules specific to the individual (Janssenswillen, 2021, 2). These glands are located at the base of the otter's tail, and are used to mark common territories, indicate sexual receptivity, communicate identity, and more (Sydney Zoo, n.d.) The glands are located on either side of the anal canal and are often expressed as feces pass through. In cats and dogs, these glands can often become impacted, or abscessed as indicated in figure 26, although it is unknown if this occurs in A. cinereus.
Fig. 27. Otters Wrestling. (Photograph by Ben124. “Otter Wrestling Match,” The Daily Otter [2021]. Retrieved November 28, 2021, https://dailyotter.org/2011/10/09/otter-wrestling-match-2/
Tactile communication, or communication through touch, is also common with A. cinereus. According to Otter Joy (n.d.) this, form of non-vocal communication occurs after even a short period of separation. Tactile communication occurs not only between monogamous pairs but extended family and new member contact. The otters enjoy nuzzling, grooming, and play-fighting, (figure 27), all in a non-aggressive way. Like human brothers wrestling around for a fun afternoon, this reinforces the bonds between groups and group members.