White-tailed deer may perceive forests in a way humans cannot: as landscapes subtly illuminated by glowing signals. Recent research reveals that deer markings—antler rubs on trees and scraped ground—emit a blue-green light detectable under the ultraviolet wavelengths present during dawn and dusk. This phenomenon adds a previously unseen layer to animal communication, blending scent-based signals with potential visual cues.
How Deer See the Glow
For decades, biologists have known that deer use scent marks to communicate. However, a new study from the University of Georgia investigated whether these marks also provide visual information. Researchers scanned 146 signposts in Whitehall Forest, Georgia, using ultraviolet lights. They found that while invisible to the naked eye, these markings re-emit light in the blue-green spectrum that deer can see.
The effect happens because stripping bark during antler rubs exposes lignin-rich inner wood, which re-emits light differently than the outer bark. The contrast intensifies as breeding season approaches, potentially because hardened antlers expose more inner wood and increased hormone activity leaves biological residues on the surfaces.
Why This Matters
This discovery challenges previous assumptions about animal communication. Traditionally, biofluorescence—like glowing fur in some mammals—has been studied as a property of the animal itself. This research suggests that biofluorescence can also be embedded within the environment, creating a subtle but detectable visual layer.
“If anyone’s seen a reflector on a tree, a rub is similar to that—although obviously not as stark,” says study co-author Daniel DeRose-Broeckert.
Deer eyes are particularly adapted to see these wavelengths under low-light conditions. The increased sensitivity to short- and middle-wavelength colors allows them to detect these subtle glows.
Skepticism and Future Research
Not all scientists are fully convinced. Almut Kelber, an ecologist at Lund University, argues that if humans cannot see the markings under natural light, deer likely cannot either. Demonstrating a visual role would require behavioral tests separating sight from smell.
The study serves as a first step, documenting the potential for contrast at wavelengths deer can see. Future experiments using natural lighting conditions are needed to confirm how deer perceive and react to these glowing signals.
This research suggests that animal communication may be far more complex than previously understood, with hidden visual cues playing a role alongside scent-based messages. Understanding these subtle interactions is essential for a complete picture of how animals navigate and communicate in their environment.
