In most circumstances, the flying squirrel has a brownish color, left. But ultraviolet light reveals them to glow hot-pink. Northland College

When we last linked to a story about flying squirrels we mentioned that we had neglected to write about them while in Kerala. However, that was not quite correct. We did frequently mention the Malabar giant squirrel, especially in guest sighting posts. Their other common name is the Malabar flying squirrel. In its own way this animal could make you gasp when you saw one, but it was competing for attention with elephants, tigers and bears. This story, thanks to Veronique Greenwood, points to other flying squirrels that might cause a completely different kind of gasp:

Flying Squirrels That Glow Pink in the Dark

While ultraviolet fluorescence is common in birds, butterflies and sea creatures, scientists haven’t often observed it in mammals.

Scientists suspect the flying squirrel may have evolved fluorescence to evade owls that hunt them. Alternately, the glow may have a mating function. Northland College

One spring night in Wisconsin, John Martin, a biologist, was in his backyard with an ultraviolet flashlight. Suddenly, a hot-pink squirrel flew by.

It was a southern flying squirrel, a small, furry creature most active at dawn and dusk. Under most circumstances, it has a warm brown color. But in the beam of Dr. Martin’s flashlight, it sported a gaudy Day-Glo hue closer to something you might see in a nightclub or a Jazzercise class circa 1988.

“He told his colleagues at Northland College, but of course, everyone was pretty skeptical,” said Allison Kohler, a graduate student at Texas A&M University.

Dr. Martin asked Ms. Kohler, then a student at Northland, to look into it. After examining more than 100 specimens of flying squirrels across two museum collections and spotting five more squirrels under UV light in the wild, the researchers and their colleagues reported surprising results last week in the Journal of Mammalogy: The pink is real.

Three different species of flying squirrel — southern, northern and Humboldt’s flying squirrel — turned that color under ultraviolet illumination.

What the flying squirrels get out of it is still a mystery. Confirming that the squirrels are even capable of seeing in ultraviolet wavelengths will require additional study, Ms. Kohler said.

While ultraviolet fluorescence in mammals has not been closely studied, it is not unheard-of in other parts of the animal kingdom.

Birds and butterflies have many brilliant markings that are usually invisible to humans, who can’t see ultraviolet wavelengths except under special lighting, but that are easily spotted by other members of their species. Fluorescence is common in the oceans, too…

Read the whole story here.