On a trip to the forests of southern India, amateur photographer Kaushik Vijayan was stunned to see massive, maroon-colored rodents leaping from treetop to treetop.

Vijayan uploaded the images of the four-pound rodents to Instagram—and the internet promptly went crazy. Some had a difficult time believing that the squirrels, photographed in the Pathanamthitta District of Kerala, actually exist, thanks to the animals’ vibrant splotches of black, cream, and burnt fuchsia.

But the Indian giant squirrel (Ratufa indica), also known as the Malabar giant squirrel, is the real deal.

"This is exactly how they look. Brilliant!” says John Koprowski, a wildlife conservation biologist at the University of Arizona and co-author of the book Squirrels of the World.

It’s “as close to purple as one gets in a mammal,” he says.

That said, evolutionary biologist Dana Krempels suspects that some of the really bright Instagram photos may have been enhanced.

"It's very possible that someone took a bit of Photoshop license to these pics," Krempels, senior lecturer at the University of Miami, says by email. "There's a setting called 'vibrance' that enhances color intensity. That's what it looks like to me."

Getting to know the giant squirrels

Believe it or not, R. indica is not alone. There are three other giants in the squirrel family, Sciuridae—each of which weighs in at two to three times the size of the gray squirrels native to the eastern United States. (Read more about squirrels.)

“The four species that make up this group are fascinating in their large size, brilliant coloration, and penchant for feeding on some of the massive tropical fruits in the tree canopy,” says Koprowski.

The pale giant squirrel (Ratufa affinis) is native to Thailand, Malaysia, Singapore, and Indonesia, and is generally brown or tan in coloration. The black giant squirrel, which is mostly black and white, (Ratufa bicolor) can be found in similar locales as well as China.

And the Sri Lankan giant squirrel (Ratufa macroura) inhabits its namesake island in addition to southern India, and is generally various shades of black and gray.

“All four species are believed to be declining, although [they are] still common enough to be frequently spotted by people,” says Koprowski.

Aside from being large and violet, Indian giant squirrels differ from almost all other squirrels in another way, notes John Wible, curator of mammals at the Carnegie Museum of Natural History.

Deciphering the Strange Behavior of Squirrels WATCH: Squirrels balance caution and curiosity as they seek and cache their food.

Instead of storing nuts and seeds in larders underground, Indian giant squirrels create caches of food high up in the treetops.

Why is the Indian giant squirrel purple?

Even among its relatives, the Indian giant squirrel stands out with its vibrant colors, which makes one wonder why evolution would select for pelage, or fur, that would call so much attention to itself.

After all, these forests are also home to predators such as lion-tailed macaques, leopards, and crested serpent eagles—all of which have been known to hunt tree-dwelling rodents. (Learn about quirky squirrel behaviors.)

No one knows for sure, says Koprowski, but the squirrel’s purple patterns likely play some sort of role as camouflage. This is because the broadleaf forests these squirrels inhabit create a “mosaic of sun flecks and dark, shaded areas"—not unlike the rodents’ markings.