Sociality and signaling activity influence river otter scent-marking behavior

We have recently published a paper in Behavioral Ecology describing our work in coastal Alaska. Using camera-trap footage, we analyzed the behavior of river otters when they visit latrines. I present and discuss here a few of the results.

Scent-marking animals communicate through smelly substances. This behavior is especially common in carnivores like badgers, otters and dogs. Scent-marking behavior usually happens in specific, known places. River otters in coastal Alaska and elsewhere use latrines to leave odorous messages for other otters that subsequently visit these latrines. The conditions that are ideal for otters to scent-mark are not well understood.

River otter groups are mostly composed by males. Males also cooperate in foraging for schooling fish. Previously, we found that smelly information left in latrines is related to events when otters join or separate from social groups.

https://www.nytimes.com/2016/09/20/science/river-otters-socialize-at-the-latrine.html

For this research, we used camera traps on latrines in coastal southcentral Alaska during summer to study the conditions under which river otters are more likely to scent mark. We worked from motorized boats, deploying cameras in recently used latrines. We documented all types of signaling and social behaviors.

Otters that were solitary and in small groups were more likely to scent-mark. This behavior was more frequent in highly visited latrines. Both the company (or lack there of) and the amount of information in the location mattered.

How come? We believe that river otters prefer scent marking by themselves or in smaller groups to avoid the dilution of their messages. On the other hand, otters favor busier, more recently visited latrines to spread their signals to the largest number of individuals. River otters in groups were more likely to scent-mark after one otter started scent marking.

Understanding when and where animals decide to scent-mark is important because such behavioral decisions can have consequences for the survival and reproductive success of otters and other species that associate and communicate in similar ways.

We thank the Alaska Department of Fish and Game for funding and supporting this research.