Cool Critters: Flying squirrels work the night shift with a glowing secret

They come out at night, have bulgy black eyes and glide through the dark. They also eat wild truffles and glow hot pink.

Northern flying squirrels are common throughout the Pacific Northwest, yet humans rarely see them. Their small size, nocturnal lifestyle and habit of soaring silently among tall trees make them nearly as elusive as Bigfoot.

But unlike the hairy cryptid, the existence of the northern flying squirrel is not in dispute. Nor is its tendency to glimmer in pink or feast on a mushroom-like fungus that is prized by humans but difficult for them to find.

Slightly larger than a chipmunk, the northern flying squirrel is found in wooded areas throughout much of Washington state, including neighborhoods and parks with lots of trees. Despite its name, it does not fly like a bird or bat. Instead, a flap of membrane known as a patagium stretches from its wrists to ankles, catching the air like a parachute and enabling the small critter to glide up to 150 feet.

“Flying squirrels can go at least 3 miles in four hours, soaring from tree to tree,” according to the Washington Department of Fish and Wildlife. Launching itself from a high branch, the squirrel controls where it glides by turning its legs and body and using its small tail like a rudder, the agency states.

Their gliding abilities are so proficient that scientists have designed a special wingsuit for base jumpers and skydivers that mimics the squirrel’s patagium, said WDFW wildlife biologist Nick Moore.

“Not only are they graceful and agile gliders, they’re also quick and quiet,” Moore explained.

As if moving through air like a brownish-gray ghost is not cool enough, flying squirrels also glow pink under ultraviolet light. The discovery was made by accident in 2019 when a Wisconsin forestry professor pointed his UV flashlight toward his backyard birdfeeder one evening, according to news accounts. Suddenly, a bright pink fur ball whizzed by.

“It was the first known observation of a flying squirrel fluorescing pink,” Moore said.

That observation led to a formal and highly publicized study of North America’s three flying squirrel species – the northern (which lives in our region), southern and Humboldt’s. Published in the Journal of Mammalogy, researchers discovered that all three species turn the same tell-tale pink under ultraviolet light. After comparing the flying species to ground squirrels, researchers found that only the flying squirrel turns pink.

Researchers know that organic compounds in the squirrels’ fur absorb UV light, which then emits it as visible light that happens to be flashy pink. Which begs the question: How come?

There’s no shortage of theories, Moore said.

It could be that the pink glow helps the squirrels see each other and communicate in darkness. Or, perhaps it evolved to confuse nocturnal predators such as owls. And yet another hypothesis is that lighting up like a glow stick helps them find and attract mates.

Then again, “maybe it’s not an adaptive trait at all,” Moore said. “We simply don’t know for sure.”

But we do know that flying squirrels – particularly our own northern flying squirrel – are adept at finding truffles beneath the forest floor and devouring them. As the truffle spores pass through their digestive systems, they are dispersed elsewhere, helping new fungi to grow.

Despite a bellyful of truffles and a Barbie-doll shimmer, the northern flying squirrel is one tough dude. Moore sometimes handles them as part of his field work tracking their populations and habitats in Washington.

“I would describe them as small, mean and feisty,” he said. “But considering the many talents they possess, I say that with utmost respect.”