Scientists ID mystery killer of decapitated seals found on California beaches since 2016
Pilar Arias
Thu, December 28, 2023 

Scientists have cracked the case of scores of decapitated seals found on northern California beaches since 2016.

Noyo Center for Marine Science's Sarah Grimes investigates marine mammal deaths, and told The Mercury News she suspected a responsible culprit, but needed proof.

"It was so gruesome," Grimes told the Bay Area newspaper. "I was like marine mammal CSI, seeing all the dead pups with their heads torn off, and I’m like, ‘What the heck did that?’"

The headless bodies were found in MacKerricher State Park, where a student at University of California Santa Cruz caught the guilty party in the act.

"We set up camera traps and got one really solid video of a coyote dragging a harbor seal pup and beheading it," Ph.D. student Frankie Gerraty said. "We are pretty confident there has been predation at four sites along the Northern California coast."

Researchers are not yet sharing the video while they continue trying to understand "the seemingly new predator-prey relationship," the Los Angeles Times reports.


Elephant seals lay on a beach near the Point Reyes National Seashore of Inverness in California on May 31, 2023.

Coyotes are appearing more often in the area after being poisoned and hunted by farmers and ranchers for decades.

"This really is nature’s balance," Grimes told the LA Times. "The coyote is not a villain. It’s part of the ecosystem that has been missing for some years."

Scientists are still working to understand why coyotes are only going for the seals' heads, leaving their bodies behind, but believe it could have to do with the nutrition content of seal brains compared to other body parts.

Point Reyes National Seashore in Inverness, California, on May 31, 2023.

Annual closures are currently in place at Point Reyes National Seashore until March 31, 2024, to protect elephant seal pups from disturbance during pupping season, the park's website says.

The seals found decapitated by coyotes are harbor seals, and research will continue into hunting patterns and the impact on the marine animal population.


Scientists solved the mystery of headless seals on California beaches

Katie Hawkinson
Thu, December 28, 2023 at 9:59 AM MST·2 min read

California coasts are teeming with marine life, so when locals encounter dead seals on their beaches, it may be a sad sight but it isn’t necessarily cause for alarm.

But since 2015, beachgoers have reported some disturbing sights: decapitated seal pups, particularly in Mackerricher State Park, around 150 miles north of San Francisco.

Experts were initially worried that a person was behind the deaths, and ecologist Frankie Gerraty told the Los Angeles Times the cuts looked too clean to be from an animal.

But now, Mr Gerraty told the Times that the mystery has been solved: coastal coyotes.

The scientist said that he captured footage of a coyote decapitating a freshly killed seal pup last year. Ecologists knew coastal coyotes scavenged the corpses of dead seal pups, but the footage provided new insight into the coyotes’ behavior.

“It’s obviously gruesome, but at the same time…coyotes and harbor seals are native species,” Gerraty told the Los Angeles Times.

“It could be the restoration of this relationship,” he added.

Mr Gerraty told the outlet that it’s still a mystery why coyotes eat the head and leave the rest of the body, but his theory is that their brains are particularly nutritious — and seal blubber is difficult to bite through.

While it may be a natural part of life, others say this spike could cause seals to change their behavior.

“I think the main challenge for the seals will be that if this becomes a bigger issue, if they start losing a lot of their pups to predation, that they might need to choose different places to have their babies,” biologist Rachel Reid told NBC Bay Area.

Researchers are calling on the public to contact the West Coast Marine Stranding Network, an organization run by the National Oceanic and Atmospheric Administration, to report any marine creatures — particularly seals — stranded on the coast, whether dead or alive.

“We learn so much about ocean health through those stranded animals,” Sarah Grimes, a marine mammal stranding coordinator and educator, told the Los Angeles Times.