Decapitated Baby Seals on NorCal Beaches Confound Biologists, But Now They Know the Culprits

Baby seals have been turning up with their heads ripped off on beaches from Santa Cruz to Mendocino County. Now researchers know who’s behind this curious phenomenon, and it’s predators with a newfound taste for seafood.

Starting in 2016, harbor seal pups with their heads ripped off suddenly started turning up on Northern California beaches from Santa Cruz, to Marin County, and as far north as Fort Bragg in Mendocino County. “It was so gruesome,” Noyo Center for Marine Science stranding coordinator Sarah Grimes told the Bay Area News Group. “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?’”

Thanks to motion-sensor camera traps, we now have the answer. UC Santa Cruz Ph.D. student Frankie Gerraty set up clandestine cameras and discovered what he calls a “Fun feature of our coastal coyote research.” But it’s not very fun for the baby harbor seals, as his team discovered that coyotes were chewing the heads off the seal pups.

“We set up camera traps and got one really solid video of a coyote dragging a harbor seal pup and beheading it,” Gerraty explained to the News Group. “We are pretty confident there has been predation at four sites along the Northern California coast.”

While marine biologists have only noticed this grisly feasting in recent years, it may be the recurrence of a situation that had been happening previously and is only reoccurring now that the populations of both species are rebounding.

Gerraty describes this relatively new phenomenon like a true Ph.D. candidate. “Coyotes are underappreciated predators in shoreline ecosystems, and marine mammals are the largest and most calorically rich nutrient parcels in the ocean, and really anywhere in the world,” he told the news group.

That said, marine biologists have no plans to interfere, and will simply let nature run its course. They figure the seals may eventually realize that the areas coyotes are beginning to feast on their pups’ heads are just not good places to raise their young.

In NBC Bay Area’s report on the coyotes eating the heads off baby seals, Virginia Tech research scientist Dr. Rachel Reid told that outlet, “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.”

If you must watch, NBC Bay Area has video of the coyotes feeding on the harbor seal pups’ heads.

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Image: Seal pup on the beach as part of the seal colony at Horsey, Norfolk, UK (Getty Images)