River Otters Use Latrines As Social Hubs

Jan 17, 2017

A still image captured at an otter latrine site.
Credit Adi Barocas

When it comes to picking a good place to socialize, the bathroom probably isn’t high on your list. For coastal river otters in southcentral Alaska, however, the bathroom is a major social hub.

Researchers are now working to understand how otters use these latrine sites to communicate and build social groups.

Coastal river otters have a somewhat unusual social system. The females spend most of their time alone and the males hang out in groups.

It’s basically the animal world’s version of a “guys night out.”

“They will play with each other, swim together and wash themselves and gently gnaw at each other’s fur and groom each other,” said University of Wyoming doctoral student Adi Barocas.

The most popular spots for male otters to gather are latrine sites – in other words, spots where they defecate and urinate.

For you or I, using the bathroom is just a basic and sometimes inconvenient part of being alive. For otters, it’s like a language. A single sniff of feces can tell an otter a lot about another individual: their sex, dominance status, even what they’ve been eating.

To help understand how latrines affect otter behavior, Barocas set up cameras along coastline in Kenai Fjords National Park and Prince William Sound. When the otters visited a latrine site, the movement triggered the camera to start recording.

The cameras recorded the otters doing something strange, right before they defecate. Barocas calls it the “poop dance.”

“The otters raise their tails at a really high angle in the air, then they’ll give a few stomps with their feet,” said Barocas.

It’s not clear why the otters do the poop dance, but it seems to have a domino effect. When one otter does a poop dance, it triggers other otters to do it.

Barocas also noticed that otters tended to congregate at centralized latrine sites, where multiple trails cross over.

“Because we’ve seen more large groups at the crossovers, the crossovers may be a station where small social units come and hang out together, gather information and get more information in their decision that’ll afterwards help them decide who to hang out with,” said Barocas.

At these centralized latrines, otters performed signaling behaviors, like the poop dance, more than social behaviors.

Barocas says these latrine sites might help otters pick which social group to join.

In other words, latrines might be the otter’s version of a high school dance – a place where lots of individuals come together, judge each other and pick which group to join.

It’s too soon to say how exactly these latrine sites affect otter social behavior. Barocas and his colleagues plan to continue monitoring the otters, hoping to unravel that mystery.

The study was published in October in the journal Animal Behaviour.