River Otters With a New Taste for Pelican Are Changing a California Park’s Ecology

“It’s got it! It’s got it! Oh my goodness, it’s got the pelican!”

When Sheelagh Halsey of Cheshire, England joined me for a wildlife safari in Point Reyes National Seashore in the fall of 2022, she and her brother were hoping to see bobcats and badgers. Instead, they ended up being among a handful of people on the planet to witness a river otter killing a Brown Pelican.

As a full-time wildlife photographer and cinematographer, I’ve also spent the past decade as a nature guide at Point Reyes. In one area of the park that I have visited hundreds of times, I’ve observed and documented river otters engaging in all manners of behavior: mating, raising their young, even fending off coyotes. But the first time I witnessed an otter attack and kill a pelican in 2019, I was truly shocked. Since then, I have seen it happen at least a dozen times, with each grisly encounter being equally remarkable.

As the Halseys and I walked the shoreline that day following a family of river otters feeding in the water, the animals suddenly turned their attention from fish to a floating flock of pelicans bathing in the middle of the lagoon. From my past observations, I instantly knew what was about to happen: moments later one of the otters torpedoed out of the water, grabbed a pelican by its gular pouch, and held the bird’s head underwater until it drowned.

The Halseys were as astonished as I was that first time. “I couldn’t believe my eyes,” Sheelegh told me recounting the attack. “It was truly unbelievable.”

River otters have a varied diet, including fish, reptiles, amphibians, crayfish, and shrimp. They are also known to hunt smaller birds such as coots and gulls—something I have personally witnessed. But watching them add a bird as large as a pelican to their meals has been fascinating. Though the behavior has been documented once before in Golden Gate National Recreation Area in 2006, by all accounts it is new for the otters of Point Reyes and has far surpassed what was observed at Golden Gate. Watching and documenting this behavior evolve over the past few years has been a remarkable experience for me and a few other lucky photographers, including my good friend Sarah Killingsworth, whose images are also included in this piece. 

While this shift in dietary preference might be surprising, there could be a simple explanation, according to Megan Isadore, executive director of River Otter Ecology Project. “River otters are opportunistic hunters,” she says. “Point Reyes National Seashore otters have discovered that pelicans here are a large and relatively easily caught source of sustenance.”

They are also plentiful. Once listed under the Endangered Species Act largely due to the impacts of DDT, Brown Pelicans have had a remarkable recovery since the banning of the insecticide in 1972. The birds officially shed their endangered label in 2009, and the current global breeding population is estimated at 370,000. In Point Reyes, numbers have followed the same trajectory, according to data from the annual Audubon Christmas Bird Count. During the 1970s, this count averaged fewer than 150 Brown Pelicans annually, but tallies in some recent years have topped 900.

The birds are most abundant here in the fall and winter, when they return or pass through from their breeding grounds in California’s Channel Islands and south along the Pacific coast to Mexico. Jutting 10 miles out into the ocean, the Point Reyes peninsula offers diverse habitat for the pelicans to rest and feed with its coastline, bays, and freshwater lagoons. This is also when the otter predation peaks.

The birds congregate in large numbers in the freshwater lagoons, where they are as equally vulnerable floating on the water’s surface as they are standing on the shoreline. When the birds are in the water, the otters swim directly into a pod to attack. Typically, the front pelicans notice the predators just in time and take to the sky, leaving the others vulnerable. On land, I have often seen the otters hunt in groups, with one charging onto the bank to flush the pod into the water for the other otters to pursue. Once they have a pelican, they grab its head or gular and hold the bird underwater until it drowns. The entire otter family begins feeding on the pelican immediately. This year, I’ve noticed that the otters are taking multiple pelicans during a single hunt more often than they ever have before.

Despite the previously recorded otter predation at Golden Gate, this behavior is largely unknown in the bird world, and what is happening at Point Reyes has also amazed others when they learn about the attacks. “The behavior is significant and fascinating,” said Kenn Kaufman, bird expert and Audubon magazine field editor, after seeing the photographs in this piece. “It seems remarkable that a river otter would attack something as large as a Brown Pelican. Of course, birds are not very heavy for their size—a Brown Pelican usually weighs less than 10 pounds, while a full-grown river otter can weigh more than 20 pounds.”

Some people have wondered whether this behavioral change is a sign of a more serious ecosystem issue affecting the otters’ typical food sources. This is certainly a possibility. Cows graze the lands immediately adjacent to the lagoon. The National Park Service website warns that streams from surrounding agricultural areas flow into this lagoon and potentially carry harmful bacteria. A 2021 media release by In Defense of Animals states water quality testing at this location exceeded water quality criteria for E.coli and enterococci. Meanwhile, the author of the paper focused on the Golden Gate otter predation posited that eutrophication of the water could be responsible for killing larger fish, fueling the dietary shift. But that was just a theory, and until more rigorous research is performed at Point Reyes, any links between habitat health and this food shift is speculation.

Interestingly, what we do know is that this addition to the river otter diet is changing the ecology of the area itself. Last year, during one walk along the shoreline where the predation is taking place, I counted more than 25 pelican carcasses. This fall there were significantly more as the pelicans have become a more prominent food source for the otters. These carcasses provide an easy meal for scavengers.

Ornithologist and naturalist David Wimpfheimer has been observing wildlife in Point Reyes for decades, and he is very familiar with the area where the otter attacks are occurring. “There has been a noticeable increase in the number of coyote sightings in this area with the recent increase in pelican predation by river otters,” he says.

River otters often stash smaller birds such as gulls among the rocks and crevices on the lagoon floor, making them more difficult for coyotes to locate and eat. (The coyotes can and will dive to find the carcasses.) But the otters don’t do this with the pelicans. They abandon them when done feeding. Coyotes with their keen sense of smell can detect the corpses and are constantly patrolling the shoreline looking for an opportunistic meal.

Several species of birds have also been observed eating the carcasses, including Turkey Vultures, Common Ravens, and Northern Harriers. Though there is no evidence yet, the bobcats the Halseys had hoped to see might also benefit. “This opens up an entirely new food source for many animals in the area.” Wimpfheimer says.

As I’ve followed this astonishing development over the past few years, I’ve often wondered if the pelicans recognize the carcasses of their species that litter the lagoon’s edge. Do they see them and not understand? Do they know and simply accept the risk? How they will adapt to this new predator remains to be seen. So far, they have shown no signs of adjusting their behavior. But one thing is clear: The river otters of Point Reyes have found a new source of food—and it doesn’t look to be coming off the menu anytime soon.

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Watch: Daniel Dietrich created a short documentary, titled A Taste For Birds, that captures instances of otter predation on pelicans. Warning: Some graphic scenes included.