The Great Chinchilla Mystery

The fluffy rodents belong high on the mountains—so how are they thriving by the sea?

close up of a furry chinchilla and one of its tiny paws
ValaGrenier / Getty

This article was originally published by Hakai Magazine.

In 2020, on a rocky hillside overlooking the vast swell of the Pacific Ocean, near the Chilean port city of Antofagasta, a local man walking his dog stumbled upon the sun-bleached skull of a small mammal. Curious, he pocketed it and brought it to the attention of the researchers Alejandro Peñaloza-García and Jaime Jiménez. The scientists were shocked. The skull belonged to a long-tailed chinchilla, a species typically found deep within the Chilean Andes Mountains. As far as scientists knew, chinchillas had never inhabited the coast.

“I couldn’t believe it at first,” says Jiménez, a researcher at the University of North Texas who has studied chinchilla ecology for more than 30 years. “There were no past records of chinchillas in the area, and never on the coast, so it just didn’t make any sense.”

The excited researchers dug into the mystery. They quickly discovered a plethora of pint-size paw prints in the sand, and rodent scat strewn among the boulders—but what they really wanted was photographic evidence. The scientists baited camera traps with apple slices and, to their delight, captured dozens of images of the rodents. It was only when they checked the cameras that they realized just how close they’d come to seeing the chinchillas—one image was snapped only 11 minutes after they’d left.

The footage shows that the coastal chinchillas are strikingly different from their Andean counterparts. As the scientists detail in a recent report, whereas the mountain chinchillas are larger, with thick fur and rounded ears, the coastal chinchillas have smaller bodies, longer tails, and unusually elongated, rabbitlike ears. Aside from their peculiar looks, the coastal chinchillas were also captured moving about in the daytime—a behavior not normally seen in wild chinchillas.

“These animals are usually completely nocturnal, so it may be a sign of fewer predators or an adaptation to their environment,” Jiménez says.

The revelation that long-tailed chinchillas are inhabiting the coast is challenging scientists’ long-held assumptions about how these animals live. For one thing, says Fabian Jaksic, a member of the Chilean Academy of Sciences who was not directly involved in the research, the find “is significant because it’s the northernmost record of the long-tailed chinchilla in Chile ever, even historically speaking.”

The environment where the coastal chinchillas reside is also a world apart from the harsh and frigid deserts of the Andes. Sandwiched between the Atacama Desert and the Pacific Ocean, life flourishes along the coastal margin thanks to the proximity of the sea and its moderating effect on daily temperatures. A thick fog known as the camanchaca rolls in on many morning easterly winds and nourishes the region’s plants.

For researchers striving to learn more about these novel animals, however, even chinchillas’ palate is puzzling.

Andean chinchillas mainly eat grass, but scientists aren’t quite sure what the coastal chinchillas eat. The hillsides they inhabit are absent of grasses but rich in flora that is either highly toxic or studded with spines and thorns. “It could be that they are eating something completely new or nibbling on a bit of everything and somehow digesting and surviving the toxins,” Jiménez says. “But this is just a hypothesis.”

Considering these differences in appearance, behavior, and ecology, scientists aren’t quite sure what to make of the chinchillas. “The coastal chinchillas might be a subspecies or maybe even a new species,” Jiménez says. “We’ll only be able to answer these questions after we’ve understood these animals and their lives better.”

Beyond their enigmatic ecology, the coastal chinchillas are raising wider questions about the species’ future.

Whereas Andean long-tailed chinchillas are still recovering from centuries of overhunting and face ongoing threats from habitat destruction as a result of mining, the coastal chinchillas seem to be thriving. If they are the same species, the new population suggests that long-tailed chinchillas are more abundant than previously thought, offering hope for their survival in the wild.

“This is probably a population that escaped overhunting due to its isolation,” Peñaloza-García says. “So there may be lots more out there waiting to be found.”