These Bay Area River Otters Have Developed A Taste for Pelicans: Report

POINT REYES, CA — Along the shores of Point Reyes' Abbotts Lagoon, a surprising predator is emerging against brown pelicans.

River otters in Point Reyes are pulling brown pelicans underwater and drowning them, according to an SF Gate report, which cites a 2024 study by the River Otter Ecology Project.

There's no single cause as to why river otters are preying on brown pelicans; however, the study suggests this is an extension of the otters' normal foraging behavior.

"It may be that larger groupings of pelicans resting on the lagoon include more isolated individuals around the periphery of the group, facilitating predation by river otters," according to the study. Brown pelicans, meanwhile, do not appear to respond to the predation by adjusting their patterns at the lagoon.

Megan Isadore, a co-author of the study, first saw this encounter in 2018 while observing wildlife at Abbotts Lagoon, according to SFGate.

Isadore saw a brown pelican flapping its wings in the water, which wasn't unusual, as it's a diving waterbird, according to the report.

But then she saw something unusual: a river otter popped out of the water, chewing on the bird, according to the report.

"This is behavior that’s different, new and not like anything we’ve seen before," Isadore told SFGate.

Despite their small stature and playful nature, experts say river otters can be violent.

In her study, Isadore refers to river otters as "opportunistic predators whose diet varies seasonally according to availability of prey species."

River otters are small and typically measure up to two-and-a-half feet to five feet long. They eat fish, crabs, birds, reptiles and frogs, according to the National Wildlife Federation.

Brown pelicans, meanwhile, can grow up to five feet in length, with a wingspan measuring anywhere from six-and-a-half feet to seven-and-a-half feet long,

The first instance of a river otter eating a brown pelican was at the Rodeo Lagoon in 2006, about 50 miles from Abbotts Lagoon, according to the study.

During one season at Abbotts Lagoon, Isadore and her co-author, Terrence Carroll, counted 73 pelican carcasses, according to the study.

Because the river otter can't finish the whole bird, they're also helping feed the surrounding ecosystem, including coyotes, according to the study.

The Bay Area isn't a stranger to mammals with strange diets. In 2024, scientists published a long-term study showing that California ground squirrels at Briones Regional Park in Contra Costa County were eating other rodents.

"In the face of human insults such as climate change and drought, these animals are resilient and have the potential to adapt to live in a changing world," lead study author Jennifer Smith told CNN at the time.

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