Over the past few years, headless seal pup carcasses have been turning up on beaches in the region, leaving experts puzzled. However, with the help of camera footage, researchers were able to capture the coyotes in the act, shedding light on their predatory behavior.

Sarah Codde, a marine ecologist with the National Park Service at Point Reyes National Seashore, described the predator-prey relationship between coyotes and seals as "exciting" and a natural occurrence. The attacks primarily targeted harbor seals at MacKerricher State Park in Mendocino County, leaving researchers baffled and the mystery unsolved for years.

Initially, experts speculated that the decapitations could be the result of human activities or a skin disease affecting the seals. It wasn't until Frankie Gerraty, a doctoral student at the University of California, Santa Cruz, set up cameras at Point Reyes and MacKerricher that the true culprits were caught on tape.

The footage revealed coyotes struggling to pull at the seal pups, with the marine mammals attempting to escape. The attacks appeared to be focused on the heads of the pups, while weaned elephant seal pups at Point Reyes National Seashore were found with chunks missing from their flippers. The reasons behind these specific attack patterns remain unknown.

"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," explained Frankie Gerraty, highlighting the significant role coyotes play in the natural ecosystem.

While the decapitations seemed to subside in 2020 and 2021, there has been a resurgence of flipper bites on weaned pups this year. Researchers are still unsure of the nutritional value or purpose behind these specific bite patterns. Tali Caspi, a doctoral student at the University of California, Davis, who studies coyotes, suggested that the coyotes may mistake the pups' flippers for carcasses and bite them before realizing they are not suitable prey.

The increasing presence of coyotes near the water has raised concerns among researchers. Seals and sea lions have become more comfortable giving birth on beaches rather than sandbars, as previous land-bound predators have been driven away by ranchers. However, with the encroachment of coyotes, the safety of these pup birthing sites is now in question.

The impact on harbor seal populations is already evident, with fewer pups being observed at MacKerricher Park. Researchers suspect that the more intelligent harbor seals may be choosing different sites to avoid the threat from coyotes. Further research is needed to understand the statewide population dynamics of harbor seals and identify potential new habitats they may be utilizing.

Sarah Codde emphasized the importance of protecting these new locations from human disturbance if harbor seals are indeed relocating due to coyote predation.

As researchers continue their study of coyote behavior and its impact on seal populations, it is becoming clear that human intervention may be necessary to ensure the long-term survival of these marine mammals in the face of changing predator-prey dynamics.