Otters in our Midst

Picking up Pier Poop

I had a wonderful day last week. I got to seek out and collect otter poop. What more could an urban naturalist want? I was with UW PhD student Yasmine Hentati, who is collecting the scat and using DNA sequencing to find out what the otters are eating. Apex predators, the otters studied so far primarily eat fish, as well as crustaceans, amphibians, birds, and small mammals, which is probably what they eat here, too. Yasmine also hopes to use the fecal samples to identify parasites and test for urban contaminants. (By the way, the correct term for said product of the otter is spraint. Who knew? Now you do, about doo-doo.)

Unlike many places, it appears that otter pelt collectors did not extirpate the Puget Sound population though they certainly decimated the sea otter population outside of the Sound. (Sea otters are not typically thought to occur south of Admiralty Inlet but apparently a lone male is living down in Carr Inlet.) The main reason for her study, which is partially funded by the Washington Department of Fish and Wildlife, is to provide basic information, such as population, diet, and home range (a male’s range tends to be larger than a females) for better management. Plus, she notes, knowing what the otters eat will help create a census of who else lives, and dies, around Seattle.

L: From Friends of Skagit Beaches R: From Woodland Park Zoo’s Carnivore Spotter, River otter sightings since 2019

In contrast to many animals, which cast their scats willy-nilly, river otters tend to tidyness, concentrating their deposits in a relatively small space called a latrine, used most likely by a family group—mom and her offspring. This could be for social reasons (river otters are rather social), says Yasmine, but no one knows for sure. In order to find the latrines, she walked many miles along the city’s salt and freshwater boundaries. (East coast river otters live up to their name sticking to freshwater habitat, whereas west coast ones inhabit both.) River otters seem to like features in a landscape, such as a peninsula or river bend, but Yasmine found her best success at marinas. “This does not endear them to people, especially when the otters poop on cleats or leave behind eviscerated birds.” Otters also produce what is known as anal jelly (don’t think too much about what it must look like), which Yasmine also collects because it contains additional DNA evidence not found in a spraint.

We collected at two marinas, Boat Street and Shilshole. In both locations, the otters chose the wood docks over cement ones. At Boat Street, where otters had made life unpleasant for one boat owner, the owner had tried to discourage them with streamers but still they pooped. “Ooh, looks like that otter had a bad day, its’a bit runny,” notes Yasmine, with the sanguinity of a seasoned researcher. At Shilshole, rain the previous night had partially disintegrated the spraints, which is not good because it leads to less available DNA. To collect the samples (#358 and #359), she picked them up with a Ziplock, placed the package in a second, more secure bag, and Sharpied them with location, date, and estimated age of deposit.

Typical spraint. Note the bits of crustacean.

Yasmine’s study is not the first in Seattle. In 2022, Michelle Wainstein and colleagues published a report of river otters based on spraints collected along the Duwamish River from its lower, Superfund stretch up into wilder areas (where it’s called the Green River). They found very high concentrations of PCBs, PAHs, PDBEs, and DDTs, exacerbated by bioaccumulation from the otters’ food source, primarily fish. Clearly, this study shows that our urban ecosystem is woefully polluted, says Michelle. But “I think perhaps of more interest is that river otters seem to be surprisingly resilient - surviving, persisting, and even reproducing despite having extremely high levels of toxic contaminants in their bodies. That’s hopeful, but ideally not cause for complacency.”

The urban environment is often overlooked as a place of wildness, where plants and animals live out their lives. Clearly, many do make their homes with us, for better and for worse, for them and for us. In doing so, they show us adaptation, tenacity, and resiliency, but, as Michelle, notes, we cannot simply sit back and watch when animals such as river otters, bald eagles, and coyotes thrive in our midst, we also need to be vigilant and continue to work to make the urban world a healthier place for these animals. Doing so is not only good for us and them, it’s simply a more equitable and fairer way to inhabit our home place.

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Word of the Week - Spraint - As noted above, it’s the word for otter poop. According to the OED, the word has been around since 1425, when none other than the Duke of York wrote about it in The Master of the Game. Spraint comes from the Old French espraintes, to squeeze out, and is cognate with our word express, and the Latin exprimere, also meaning to squeeze out. I did not make this up, one of the many reasons I love words. (And, despite what some say, espresso’s origins lay in making the drink on the spot, as opposed to it being squeezed, or pressed, out. Oh well.) What’s unclear is why otters merited this specific word for such a common thing.

The Duke’s words about otters, where you can learn other fine information, too.