Baby Seals Were Being Beheaded on Northern California Beaches. We Now Know the Culprit.

Researchers have uncovered the unsettling mystery behind a series of headless seals discovered on the beaches of MacKerricher State Park near Fort Bragg. The gruesome scenes date back to 2015, with dozens of decapitated seals found each year, sparking investigations into the unknown predator responsible.

Ph.D. student Frankie Gerraty from the University of California, Santa Cruz, decided to tackle this baffling phenomenon. Setting up motion-sensor cameras along the California coastline, he hoped to catch the culprit in action. On April 23 at 11 p.m., Gerraty’s camera captured the startling footage of a coyote dragging a seal pup onto the beach and beheading it before disappearing from view.

This discovery has led researchers to delve deeper into the behavior of coyotes, seeking to understand why this trend is occurring in certain NorCal locations and what consequences it might have for the local marine mammal population. While coyote predation alone may not significantly reduce harbor seal populations, it could lead to shifts in their choice of habitats for birthing and raising pups.

There are also concerns that seals’ tissues, laden with contaminants like mercury from the marine food web, might be transferred to land-dwelling animals through coyotes’ consumption habits.

Photo via A. Kopshever/National Park Service

The study is ongoing, with more data expected to be collected from camera traps in the spring. The full results are not anticipated until late 2024 or early 2025. Researchers believe this discovery highlights the intricate relationships between marine mammals and terrestrial animals and could represent a restoration of a historical ecological connection.

While researchers are still trying to comprehend this “seemingly new predator-prey relationship,” they have not yet released the video to the public. Coyotes have been appearing more frequently in the area after decades of being hunted and poisoned by farmers and ranchers.

While the mystery of why coyotes specifically target the heads of seals remains unsolved, researchers speculate it may relate to the nutritional content of seal brains or the ease of accessing this part of the animal’s body. The decapitated seals are harbor seals, and ongoing research will delve into the hunting patterns and the impact of these predations on the marine animal population. Annual closures are currently in place at Point Reyes National Seashore until March 31, 2024, to protect elephant seal pups during their pupping season.

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