There have only been 59 documented attacks by otters of all species. (Photo by U.S. Fish and Wildlife Service)

The three women who were recently attacked by an otter while floating on the Jefferson River near Three Forks stood about a near-equal chance of being charged by an angry unicorn.

Otter attacks with injuries or fatalities are so rare that biologists have tracked a very specific number: There have only been 59 documented attacks by otters of all species.

Since 1875.


For comparison, it’s estimated that 25 people on average in America die each year after getting struck by lightning.

In Montana, where river otters are plentiful, the state’s Department of Fish, Wildlife and Parks reports only one other case of an otter attack recently: A 2021 occurrence on the Big Hole River.

While the attack attracted the attention of the public because such behavior isn’t normally associated with the lovable, furry creatures who lope on land and glide gracefully through water, the incidents haven’t raised hackles with state wildlife officials who say the behavior, while rare, isn’t out of character.

“Typically, we don’t try and track down animal attacks unless it’s behavior that’s abnormal. In the cases mentioned above, we didn’t try and find the otters as the behavior wasn’t seen as abnormal,” said Montana FWP spokesman Greg Lemon. “Otters can be aggressive when protecting a den or a food source.”

Otter behavior expert Heide Island, a professor at Pacific University in Oregon, agreed: While otter attacks are exceedingly uncommon, the aggressive nature of this mad mustelid can be explained.

She told the Daily Montanan that most of the time, wild river otters avoid interaction with humans. But they can become aggressive while defending their territory, their young or food sources. And just from the limited information she’s seen published on the most recent Montana attack, she believes several of the criteria could have been met.

Island said it’s helpful to understand a bit of otter biology: July and early August are key for female otters – it’s when they start weaning their pups, teaching them how to swim, hunt and survive. By mid-to-late summer, the pups are big enough and strong enough to begin venturing outside the den. Pups spend a year with their mother, Island said, and most give birth in March or April, depending on the season and the condition of the otter.

Otters are also crepuscular, meaning they’re most active during dawn and dusk hours.

Because of the timing and because the attack happened on the river near dusk – approximately 8:15 p.m. – Island said she is almost certain the ornery otter likely had young pups nearby and perceived the women as a threat.

River otter facts

“If you see an otter nearby and you’re on the water, the best advice I can give is – get out of the water,” Island said. “On land, you have the advantage. In water, they do.”

Island points to two articles that track dangerous or fatal otter attacks worldwide. They show that from 1875 through 2021 only 59 attacks occurred worldwide. Though 20 of those are since 2011, half of those incidents are from Florida, making angry encounters even less likely in places like Montana.

“If you look at these even more closely, almost all involve the water or were along river banks,” she said. “I am deeply sorry to those people who were hurt. It seemed to come out of nowhere. Sadly, that’s usually the experience.

“People need to be mindful, not afraid.”

As an animal behaviorist who got her doctorate from the University of Montana, she said that most of the time people don’t see otters until they’re very close; their heads and bodies, a dark brown, usually match the color of the river bed and they barely rise from the water. Unlike other animals, otters don’t roar or make other sounds, and few recognize an otter den.

“Usually, if there are beaver in the area, there are otters,” Island said. “They can actually look snake-like. They’re elusive anyway and tend to be very mindful of human behavior. My guess is that (the attacking otter) felt threatened and she had young nearby because this is the time she’s weaning.”

The other otter

By strange coincidence, the attack on the Jefferson River isn’t the only otter-related news making headlines.

California authorities are searching for an otter, named “Otter 841,” which has developed a habit of going after surfers near Santa Cruz, prompting U.S. Fish and Wildlife Officials to plea with the curious public not to disturb otters.

Island said she’s been called upon by the media to help explain that otter behavior, too. She told the Daily Montanan she doesn’t believe the otter in California is as interested in the people as it may be interested in the surfboard. Island has helped document otters’ innate curiosity, plus they’re known for using tools.

However, she also said that more people charging into otter habitat can not only lead to more human-otter encounters, increasing the chance of injury, it can also drive the animals away from their habitat.

“The best way to lose an animal is to encroach on its territory,” she said.

Daily Montanan and the Oregon Capital Chronicle are part of States Newsroom, a network of news bureaus supported by grants and a coalition of donors as a 501c(3) public charity. Daily Montanan maintains editorial independence. Contact Editor Darrell Ehrlick for questions: Follow Daily Montanan on Facebook and Twitter.

Darrell Ehrlick is the editor-in-chief of the Daily Montanan, after leading his native state’s largest paper, The Billings Gazette. He is an award-winning journalist, author, historian and teacher, whose career has taken him to North Dakota, Minnesota, Wisconsin, Utah, and Wyoming. With Darrell at the helm, the Gazette staff took Montana’s top newspaper award six times in seven years. Darrell's books include writing the historical chapters of “Billings Memories” Volumes I-III, and “It Happened in Minnesota.” He has taught journalism at Winona State University and Montana State University-Billings, and has served on the student publications board of the University of Wyoming.