Since 2016, headless seal pups have been turning up along the California coastline – and scientists have finally found the culprit.
While they originally feared humans may have been to blame, the messy decapitations suggested another animal may have been behind the gruesome behaviour.
Now, thanks to some wildlife detective work and camera traps, a PhD student has revealed coyotes have been preying on the young pups.
A cousin of the pet dog, coyotes are more commonly thought of as scavengers that also hunt small animals and livestock, rather than skilled predators, but the new video footage upends that notion.
‘We set up camera traps and got one really solid video of a coyote dragging a harbour seal pup and beheading it,’ said University of California student Frankie Gerraty, who captured the footage. ‘We are pretty confident there has been predation at four sites along the Northern California coast.’
Mr Gerraty and the team were trying to determine whether coyotes commonly eat seafood, or if they were just opportunistic diners.
Speaking to the Mercury News, he added: ‘Not many people think of them as beach dwellers, but they definitely are.
‘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.’
The mystery was one that had baffled stranding coordinator Sarah Grimes for years after the carcasses began appearing.
‘It was so gruesome,’ said Ms Grimes, who works at the Noyo Center for Marine Science in Mendocino County, north of San Francisco. ‘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?”.’
But while the culprit has been solved, the motive behind only eating their heads is still under investigation.
Coyotes: the lowdown
The coyote, scientific name Canis latrans, is a member of the dog family.
However, they are more closely related to wolves than our pets.
Coyotes can be found across North America, from Alaska in the norther and stretching into Central America, proving how versatile and resourceful they are.
This also means they vary considerably in size and colour depending on where they live, although on average they are about 60cm tall, with a reddish/grey coat.
They’re also fast, reaching speeds of up to 40mph.
Their most famous trait however is a distinctive howl, often heard across the plains of North America at night.
‘My guess is that the brains are pretty nutritious compared to a lot of other seal parts,’ said Mr Gerraty, speaking to the LA Times. ‘Blubber can be pretty hard to get through.’
It is also unclear how this new behaviour will affect the seal population – or even if it is new. Coyotes could have been hunting seals for centuries without humans noticing, or may have returned to eating them in recent years after their population recovered following decades of decline.
Habitat destruction could also have driven the versatile coyotes to the coast.
On the other hand, coyote numbers are also growing thanks to conservation efforts following decades of poisoning and hunting by farmers trying to protect their livestock, meaning there are more around to venture into the waves.
‘It’s obviously gruesome, but at the same time… coyotes and harbour seals are native species,’ said Mr Gerraty in the LA Times. ‘In reality it could be the restoration of [a previous] relationship.
‘As these predators are recovering, it’s really interesting to think about how the ecological relationship may be coming back or not.
‘The coyote is not a villain. It’s part of the ecosystem that has been missing for some years.’
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