Flying squirrel under visible light and UV light

A museum specimen of Humboldt’s flying squirrel looks brown under white light but fluoresces bubble-gum pink under ultraviolet light. Credit: A. M. Kohler et al./J. Mammal.

Ecology

Flying squirrels are secretly pink

Forest ecologist stumbles across a New World gliding rodent that glows rosé in ultraviolet light.

Nature is more colourful than most of us realize. Many plants and animals have been found to sport dazzling fluorescent patterns that are visible only under ultraviolet light.

Paula Spaeth Anich and her colleagues at Northland College in Ashland, Wisconsin, have added another species to the list with the discovery that New World flying squirrels glow hot pink in UV light — a rare example of fluorescence in mammals. One of the researchers inadvertently revealed the hidden glamour of squirrels in the genus Glaucomys while using a UV light to study lichens in a Wisconsin forest. This chance observation of a shimmering squirrel was supported by an examination of 135 museum specimens across 3 squirrel genera. Only Glaucomys glowed pink under UV light.

The role of the hot pink fur is unknown, but the team say it could help the animals find — and perhaps impress — each other in low light. The pink fur pattern could also mimic the plumage of owls, which possess a similar secret glow, to confuse avian predators.