This is Scientific Americans 60 Second Science. I'm Jason Goldman. Got a minute?

River otters, like other social animals, have to carefully weigh the costs and benefits of hanging out in large groups.

A big group makes it easier to catch fish, which seems like a good deal,

but there's a downside to social life too.

More otters means more chances for disease. But there's a downside to social life too.

More otters means more chances for disease transmission,

for example, or for aggressive conflict.

So they balance these pressures by living

in what researchers call a fission fusion society.

So there's this constant dynamic of splitting and sort of joining into larger groups.

University of Wyoming Ecologist Ade Barocus.

To understand the factors that drive these social dynamics, Barocus's team, from the University

of Wyoming and the Alaska Department of Fish and Game has spent decades spying on the coastal river otters of Alaska near Prince William Sound.

To do it, they use motion-activated camera traps as well as implanted radio trackers.

The trains, what we call a train which are pretty much communal toilets that the river others use.

They seem to be, seem to have an important function in the life of rigor otters.

That's right, river otter society is organized around the bathroom.

It makes good sense.

By investigating a latrine, an otter can sniff out just how many otters there are in the area and who they might be.

The researchers found the otters performed more signaling behaviors like sniffing, body rubbing, or urinating,

than social behaviors like grooming or play at what they called crossover latrines, which were

located at the junctions of water bodies.

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