River Otter Poo-pori of Facts
North American river otter (Lontra Canadensis): Photo- Publicdomainpictures.net)
Things You Didn't Know You Wanted to Know About River Otter Poop
Working with kids and the public it's hard to stay away from topics that make people go "eww" and get grossed out, because it grabs their attention. Now that's not to say that all of my program include poop, but there's something about scat or poo that helps people draw comparisons to themselves and find connection (if not humor) in nature's potty-paws. I'm fortunate enough to live in an area with active population of river otters (Lontra canadensis). Most of you are probably familiar with the cute and fuzzy sea otters of the West Coast of the US, but the river otter of the Eastern seaboard and inland spaces is sleek and fun too. In this post I want to introduce you to ten facts about river otters and their poop, because poop plays a central role in a river otter's social life, and their social life centers around pooing.
A single otter poop is called a "spraint" like a "spraint" ankle. A place where there are multiple spraints is called a latrine.
Latrines are the social hubs for otters. When you're a medium sized mammal (3-4' long or smaller) then you have to weigh the cost/benefit of hanging around in big social groups. Sure, you could "chat more" with your friends, and get help fishing, but you'd also be competing for resources too (from female otters to food). This is why otters poo in latrines. The latrines act like the world-wide-web for otters, it's a communication in stinky that keeps them up to date on the neighbors and allows them to live alone (like most female river otters) or in small groups (like most male otters), while being in a larger community. There is some debate in the river otter world about whether or not otters are territorial, so spraints are really more communal than purely territorial.
This is an example of a bit older otter spraint, usually they are a touch darker grey but this one has been outside a week or so (Photo: K. McDonald)
Spraints contain a lot of information.
It is known that otters can differentiate their own poo smells, that of others, and the estrus state of females (if she's breeding or not). These poo-grams are also thought to convey information about who is in the "hood," and their health as well. Not only do otters spread fecal-facts but they also rub at the sites, leaving behind scent and smell as well. Green and Monick, Journal of Ethology, found that otters actually spend more time, standing, sniffing, and rubbing at spraint sites than just pooing.
Otter's don't just make spraints, they also make "anal jelly."
We're not talking about the canning kind of jelly here, we're talking full on stinky intestinal lining. Otter anal jelly is not the kind of jelly you're thinking of either. It's thought to be the shedding of the intestinal lining of the otter, along with some undigested bits of food, and anal secretions to add some aroma. Anal jelly is usually not the same color of spraints, and it has a jelly-like consistency. The anal jelly I've seen is usually white or tan, and makes a stinky puddle. these jelly filled poos are also found at latrines, and scientists use them to harvest DNA for studies of individual otters. It's easier to get DNA from stomach lining than from poop. Yes, scientists have studied this (for European otters mostly) and you can read all about it here.
Otter anal jelly (Photo: K. McDonald)
River otters sometimes dance when they poo.
One of the rituals that river otters are known for is something called the "otter poop dance." Yes, it's a real thing. I'll share a video below, you can also find several on Youtube. I've not found any good reason for this ritual, but it makes me laugh.
We can learn a lot about what an otter eats from its poo.
There is a world of information that otters can get from each other's poo, but scientists find it useful too. Here are just a few ways scientists can:
- Tell what a river otter eats and what is in season (from crayfish to crabs and fish to ducks)
- Age the fish that the otters eat by counting the rings on the fish scales (like tree rings), this gives an idea of the age of the populations of fish they are eating, and their health
- Estimate river otter populations by sampling DNA, looking at frequency of the spraints being laid down and how fresh they are
- Track the estrus cycles of female otters and when they are ready to breed
- Monitor fission-fusion events in otter populations, this is fancy science speak for when groups of otters come together to be social, and when they break up into smaller groups to hunt and forage. Fission-fusion events have implications on disease rates, information transfer, and the change in group dynamics (who goes to hang out with whom).
Yes, there is a protocol for cleaning otter spraints to get this information, it involves dish soap, shaking, sieving, and baking (to kill off parasites/bugs), but it's surprisingly not as smelly as you may think. In our region the spraints are mostly made up of fish scales and a few duck feathers, with crabs thrown in during the warmer months. These aren't so smelly with the flesh removed by the otter by its digestive system.
Fish bones and scales from a river otter spraint (Photo: K. McDonald)
Spraints can also tell us about the health of an otter.
Studies about European otters showed that in one project over 36% had Toxoplasma gondii, which comes from domestic cats. A study by researchers at UC Davis in California found the same issue, sea otters were also infected by the single celled parasite Toxoplasma (also called Toxoplasmosis), which comes from runoff from the land. Otters found near heavy freshwater flows from land are 3x more likely to be infected than those not near freshwater flows. This is thought to be a major contributing factor to the decline in sea otter populations in the region.
River otter spraints can also have other parasites too, ranging from different types of nematodes to trematodes (worms, don't worry about the names, just flat or round). Where I work we've found lots of long round-worms in the spraints, possibly trematodes, or worms that live in mollusks and whose life cycle requires mammal guts and later a snail for reproduction (nature is so weird and cool).
Nematodes or worms found in otter spraint (Photo: K. McDonald)
Otter latrines are geographically specific.
Otters, like people, like to hang out in conspicuous places (at least to them). After all, you want to leave your poo-pori laden stink at the place where there are the most otters. To find otter latrines scientists did a bit of work trying to figure out what makes a latrine site just about as desirable to otters as malls to teenagers. Typically otters like to mark in areas of high traffic, where either trails or water bodies intersect, and areas that are fairly undisturbed by people as well as easy to watch from for predators. These areas are different depending on if you're studying in inland Colorado or the Chesapeake Bay. For us it's floating docks and finger piers. Knowing where otters like to be social, and spraint can help researchers study them. There are whole papers on multivariate statistical analysis of potential otter latrine sites (if you're looking for some light bedtime reading).
Spraints could be used to track other local carnivores.
Let's face it, if you're a giant carnivore researcher tracking bears and pumas, wouldn't it be easier not to have to chase after them, trap them, tag them, etc.? Well, there may be an easier way, you got it, otter poop! Scientists in New Jersey used camera traps located at otter latrines to see if they could capture images of other carnivores that might be drawn to the spot by the smell. They found that all sorts of animals were drawn to the traps:
"....the overall carnivore detection frequency was 3.5 times greater at latrines, and the detection frequencies for red foxes (Vulpes vulpes), northern raccoons (Procyon lotor), river otters, mink (Neovison vison), long-tailed weasels (Mustela frenata), and Virginia opossums (Didelphis virginiana) were greater at latrines. American black bears (Ursus americanus) and eastern coyotes (Canis latrans) where detected more frequently at non-latrines. Our study provides evidence that placement of camera traps at otter latrines may serve as a new and novel approach for monitoring carnivore populations in riparian areas (Wagnon and Serfass, Ecology 2016)."
Can you spot the fox visiting this latrine? (Photo: K. McDonald)
Bet you didn't know there was a lot to learn from river otter scat. Regardless of whether or not you find poo to be too disgusting to deal with, or you find it funny to joke about, it's a real tool for researchers. When you're out and about, along rivers or lakes, keep an eye out for otter spraints, and see if you can tell what they have been eating, and who has been visiting.
Just because it's fun, here's another otter poop dance (4 minutes of otter poop dance fun).