GLOWING PINK FLYING SQUIRRELS: Biofluorescence Revealed

Southern Flying Squirrels, Glaucomys volans, glowing hot pink on their underbellies when illuminated by a 365 nm UV flashlight, in a rare phenomenon known as biofluroescence

I awoke last night at midnight to flashes of light from a motion sensor floodlight on our deck. I wasn’t thinking of prowlers, because I suspected the flashes of light were triggered by Southern Flying Squirrels coming to visit for the sunflower seeds I had tossed out just before going to bed.

I crept downstairs and carefully opened the sliding door, letting in frigid February air. The deck light came on briefly, enough that I could see the tiny squirrels dashing up through an opening in the deck around a huge Northern Red Oak. Each squirrel would come up, grab a sunflower seed, then dash down the tree trunk out of sight. This happened so fast that I couldn’t see how many squirrels there were, though at one point I saw three. There may have been more. On this night they were nervous and did not stop long enough for any photos.

We’ve had Southern Flying Squirrels at our home in Michigan each winter, and I’ve photographed them at night several times using incandescent lights on the deck. They made for good photographs, with their gray-brown fur and a cuteness factor of huge bulging eyes and little pink lips, but their coloration was subtle to my eyes and essentially no different from most mammals, which are colored for camouflage rather than display.

Then scientific knowledge suddenly changed. About four years ago a Wisconsin forestry professor, Dr. Jonathan Martin at Northland College, was in the woods at night looking up toward the forest canopy with an ultraviolet flashlight for lichens and other fluorescing lifeforms, when a hot pink missile glided overhead. He identified this as a Northern Flying Squirrel, and its normally white belly lit up hot pink in ultraviolet light. He found this astounding, and asked a colleague to investigate flying squirrel skins in a couple of museum collections to see if the phenomenon could be confirmed. It turned out that in those collections, the bellies of all three species of North American flying squirrels–Southern, Northern, and Humboldt’s Flying Squirrels–glowed bright pink under UV light. Even specimens over 100 years old. Male and female, young and old, they nearly all glowed.

Since we have easy access to flying squirrels at our home in Central Michigan, I decided to observe this phenomenon for myself. I obtained a 365 nm UV flashlight that is powerful enough to look almost into the treetops and began looking at these squirrels on nights they chose to come to our feeding station. They don’t come every night, but when they do I often get up in the middle of the night to observe and try to photograph them. It isn’t easy to photograph little nervous squirrels by a relatively dim (to our eyes) UV light, but I’ve had some success represented by the pictures here.

Southern Flying Squirrel showing biofluorescence under UV light on the left, with the same species illuminated by tungsten light on the right. The belly fur changes from off-white to bubblegum pink when struck by UV light.

Why do flying squirrels glow? That is still unknown. What is known is that at dusk, dark, and dawn, the air is bathed in proportionately more ultraviolet light and far less light from the visible spectrum than in daytime. This UV light–when converted to visible light by fluorescence–makes the flying squirrels more visible to each other. This is even more true when snow blankets the forest, since snow reflects UV light. It also appears that flying squirrels’ eyes, unlike ours, can see into the UV spectrum, so this ability may also be involved.

Again: why do they use biofluorescence and UV light at night? There are a couple of possibilities that spring to mind. Based upon the three flying squirrels I observed on that recent February night, I think it’s possible that the squirrels use their bubblegum pink undersides to keep track of each other at night. These squirrels are highly social, with reports of 25 to 50 Southern Flying Squirrels roosting communally in a hollow tree. So why wouldn’t they follow each other to food sources? Some of my pictures show them sitting side by side, dining quietly together on the sunflower seeds I put out. They seem to enjoy a more peaceable kingdom among their kind than do the daytime Eastern Gray Squirrels and American Red Squirrels we also get in Central Michigan. Feeding together also means more big eyes to look for predators–much as goldfinches and other songbirds feed communally as a strategy to detect hawks.

There is another tantalizing possibility for the pink color. Three large owls that also live in this region–Barred, Barn, and Great Horned Owls–also have bellies that fluoresce hot pink under UV light, though their coverings are feathers rather than fur. These owls are the chief predators of flying squirrels. Do the flying squirrels mimic the owls to fool the predacious birds into thinking they are seeing other owls when in the air? Maybe. I find this possible. The fluorescing fur is mostly on the belly and undertail of the squirrels, with just a minor hint of color change on the back and virtually none on the tail. Once a flying squirrel lands on a tree trunk, its back and tail make it almost invisible to predators because the glowing belly is nearly hidden.

Alternatively, perhaps the owls are mimicking the flying squirrels, fooling the little squirrels into thinking they are seeing others of their own kind. This would allow the owls to silently approach the flying squirrels and suddenly grab the little creatures.

Or perhaps all three of these mechanisms are in play: bubblegum pink signals the presence of flying squirrels to each other, but also both disguises them from owls and identifies them to owls, if any of that makes sense. Coevolution at work.

Biofluorescence also extends to the Virginia Opossum in this region, but is apparently unknown in other mammals here. It turns out the phenomenon is new enough that the chemical and physical mechanism is still unknown. I suspect this will be studied in coming years, with possible applications for industry. Or not. Knowledge is its own reward.

I will be watching these creatures over the coming weeks and years, both with and without the assistance of UV light. The mysteries of nature are an ingrained part of my life and I find observations and photography endlessly fascinating.

The photographs above are a good representation of the Southern Flying Squirrel in UV vs visible light. The final photograph shows the deck setting at night where all the pictures were taken, and includes one flying squirrel for scale. Click on the photographs to see them larger.

Here are some other sources that examine this discovery:

Ultraviolet fluorescence discovered in New World flying squirrels (Glaucomys) (Journal of Mammalogy)

Southern Flying Squirrel (Wikipedia)

Flying Squirrels Glow Fluorescent Pink Under Ultraviolet Light (Smithsonian)

SHADOWS

Moon shadows. Sun shadows. Street light shadows. All it takes is a point light source that reveals the world to our eyes, while casting into shade those places not illuminated. The light examines, while the shadows add mystery. And definition. And design.

I have worked extensively with shadows as a compositional tool during the last few years, and here I present some of my favorite photographs from this era of my life.

GINGERBREAD

On the end of a sunny day in March, the sun was shining warmly upon the land, with trees casting their organic shadows across the faces of buildings. I especially liked this old farmhouse, which had just a touch of gingerbread trim left from an earlier era.

LOCATION: Central Michigan, USA

SHADOW PLAY

Spring shadows crossing a snowy field, then gliding up the front and roof of a house. These are the kinds of compositions I notice, putting a subject in a whole new light.

LOCATION: Mormon Row, Grand Teton National Park, Wyoming, USA

SNOWSTORM IN A REMOTE VILLAGE

While visiting Newfoundland in midwinter, we stayed in a cozy home once used as a cod fisherman’s residence. I walked out at night during a heavy snowstorm and photographed homes and a church in the village. The falling snow leaves a slight texture in the sky, and the warmth of lights coming from inside the house lend a human touch. There is an air of mystery in this photograph that encourages repeated viewing.

LOCATION: Dunfield, Newfoundland, Canada

WINTER NIGHT BY THE SEA

On a February trip to Newfoundland we stayed at an old house right along the Atlantic shore in a tiny fishing village. It was magical. Then it started snowing. I took this picture with a very long exposure to blur the snowflakes, which adds an interesting texture to the dark background.

This picture is one of the rare pictures where I worked on the scene extensively using Photoshop. I modified the color that came from the sodium vapor street lamps and chose instead to bring the red colors and the snowy landscape back to what they look like in the daytime, and I think it looks painterly. It is my interpretation of the scene, and I like the feeling of it.

LOCATION: Dunfield, Newfoundland, Canada

DARKNESS ON THE EDGE OF TOWN

Returning late from a snowshoe trip to the Mount Baker area, we stopped in the small town of Maple Falls to get a sandwich and gas. It was quiet, and the darkness beyond the brightly lit gas station reminded me of the paintings of Edward Hopper–one of my favorite American artists. I carefully composed the photograph in several ways, and this turned out to be my favorite. The name for the photograph comes from a Bruce Springsteen album, which has some of the same thematic elements as this photograph: the power of darkness, the lure of the open road, and the magic and threat of night.

LOCATION: Cascade Mountains, Washington State, USA

PASSAGE

Utah’s Nine Mile Canyon is known for the petroglyphs and pictographs along its some forty mile route. But on this autumn day, an old cabin captured my lens. The mind has to puzzle out what is going on here, and that is part of the mystique of this picture.

LOCATION: Nine Mile Canyon near Price, Utah, USA

CURVE IN SPACE AND TIME

At the end of a spectacular Great Plains sunset, I had just finished photographing a grain elevator with a wash of sunset warmth. Leaving, I immediately crossed these railroad tracks, which reflected the orange and magenta colors in the sunset. I quickly turned the vehicle around and returned to photograph this wonderful curve in the universe. Grace in steel and light and darkness.

LOCATION: Boise City, Oklahoma, USA

STREETLIGHT SHADOWS ON SNOW

It was the dead of winter with a fresh layer of snow upon the ground. I was tired from driving home at night, and stopped at a rest area for a few moments of respite. There I noticed the orange sodium vapor lights casting their eerie glow upon the snow, with tree shadows adding grace and lines to the scene. I spent a long time trying to get the perfect composition without disturbing the snow, and this was my favorite for its organic lines and rich color.

LOCATION: Central Michigan, USA

TULIPS IN SUNSET GLOW

On a spring visit to Alaska, where my brother and his wife have raised a family, I noticed the warm sunset light glowing on the walls. I picked up a camera and began photographing the shadows and patches of light all over the house. When my sister-in-law saw what I was doing, she held up a vase of tulips to create these shadows on the wall.

LOCATION: Chugiak, Alaska, USA

BLUE WINDOW AND ADOBE SHADOWS

I like visiting Taos in October, when the warm, low angle sun sets the adobe afire with color. In this photograph, I captured a classic blue-framed window at the end of a crystalline day, with delicate leaf shadows adorning the adobe, as if painted by an artist.

LOCATION: Taos, New Mexico, USA

OCTOBER IN SANTA FE

With the aroma of pinyon logs burning in fireplaces, the cottonwoods sifting golden light through autumn leaves, and the piercing blue sky, Santa Fe is a special place in October. While browsing the art galleries along Canyon Road in late afternoon, I came upon these flowers and their shadows at an adobe house. This photograph brings back fond memories of a wonderful place and time.

LOCATION: Santa Fe, New Mexico, USA

RAINIER AUTUMN

I was high on a ridge at sundown, when the sun was casting long autumn shadows on the colorful autumn meadow. The fir trees, with their pointed tops, create a strong graphic statement.

LOCATION: Paradise, Mount Rainier National Park, Washington State, USA

NIGHT SHADOWS ON AN ADOBE CHURCH

San Francisco de Asis Mission Church is one of the finest photographic subjects I have ever encountered. In the course of one October day, I returned three times to photograph the church under different lighting conditions. This photograph is among my favorites: taken at night, the adobe walls are graced with shadows cast by a streetlight shining through cottonwood leaves. It has an interesting juxtaposition of shadows and shape and the texture of adobe, and even has stars overhead.

LOCATION: Taos, New Mexico, USA

SHADOWFAX

Shadow of a car moving fast on a Michigan highway in the late light of an early autumn day.

LOCATION: Central Michigan, USA

DANDELION TWILIGHT

While camping in Hell’s Gate State Park, I noticed how the occasional vehicle passing by my tent illuminated the dandelion seedheads in the grass. I loved the backlit look of the dandelions and the shadows cast by the trees, so I employed my van as a photo prop and set up this picture at deep twilight.

LOCATION: Lewiston, Idaho, USA

AMISH BARN IN WINTER

This is a recently built Amish barn in Michigan. I love the simple lines of it, suitable for the people who built it, with functionality foremost and certainly no embellishment. Look at the lines of the walls and roof and shadows: how they intersect each other and how they define the blocks of red and blue colors. This is another in my series studying how light falls on buildings, inspired by Edward Hopper’s paintings that worked with this theme.

LOCATION: Central Michigan, USA

BLUE SHADOWS

Amish homes near my Michigan winter home are austere, with white paint and no superficial adornment, including flower beds or foundation plantings (interestingly, many have bird feeders outside the windows to bring color and life into their lives). In this photograph, I saw the blue shadow at the end of the day crossing the simple white house and thought it added a gaudy and unexpected touch.

LOCATION: Central Michigan, USA

All of my photographs are available for sale as prints, either on cotton rag paper or on metal. Go to http://leerentz.com to see my entire catalog. If you would like one of the photographs shown here in the size I have listed below, you have the option of ordering it through PayPal.

SHADOWS PHOTOGRAPHS FOR SALE

The photograph shown to the left is simply an example; any of the above photographs are available for ordering. Please indicate which of the above photographs you would like to order. This is a 16 x 24″ metal print on aluminum with high gloss surface and incredibly rich and accurate color, ready to hang with no picture frame necessary (slightly rounded corners, stands about 3/4″ out from the wall for a floating, modern appearance). You can see a much larger selection of print sizes and types at my website: http://leerentz.com. Shipping is free; sales tax will be added for Washington State residents. I am glad to answer any questions at lee@leerentz.com

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SPOOKY REST AREAS LATE AT NIGHT

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After miles of drizzle and fog on an early December night, I needed to stop for a break. A blue rest area sign caught my headlights, and I decided to pull over two miles ahead. Rolling to a stop in front of the restroom building with only one other car visible, I scanned the grounds for potential trouble, then got out of the car, carefully locked it, and went inside. All was quiet, and nothing untoward happened.

Tree Shadows Crossing a Snowy Winter Landscape in MichiganI took the photographs in this weblog post in three different rest areas during the winter of 2014/2015.

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Plains Indian Tipi Motif in a South Dakota Rest Area

For me, visits to highway rest areas are often like that: a little spooky and unsettlling, especially late at night. When I leave the comfort zone of my vehicle I make myself more vulnerable, but usually the short stop is uneventful and barely registers in my memories. It is worth remembering, however, that danger can sometimes lurk in quiet and remote places.

Shortly after I drove through Minnesota on my way to Michigan, I read a news story about a young man from Washington State who had been murdered execution-style around midnight by another man from the same state–in Minnesota’s Elm Creek Safety Rest Area. Someone reported the murder, and a red SUV speeding away from the rest area. That led to a 115 mph chase in which the suspect was shot and killed by police after crashing his vehicle in the median and emerging with a gun. Since both men were dead, the circumstances and motives were unknown. Apparently my apprehension about stopping at night is justified …

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Tree Shadows Crossing a Snowy Winter Landscape in Michigan

While lying in bed this morning and thinking about writing this weblog post, I remembered a story from long ago. It seems that two guys I knew in grade school and junior high had moved to the Boston area and were working in a camera store. According to the news accounts, they forced a coworker to accompany them to a rest area, where they robbed him and stabbed him to death. I had repressed this memory for decades until I started writing this story, then it popped into my mind like a nightmare. The thing was, I could understand how one of the boys could end up as a killer, because he had always been a mean little snot, but the other kid was just a sweet, normal boy who apparently followed the other into a life of horror.

Plains Indian Tipi Motif in a South Dakota Rest Area

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Tree Shadows Crossing a Snowy Winter Landscape in Michigan

Those stories and others like them feed the fear factor in my brain, but they also gave me some of the inspiration for this series of photographs. These pictures can be seen as beautiful in their own right, but they also have an edge of spookiness that is appropriate for the subject.

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Signs and Parking Lot in Rest Area along Interstate 90 in South

Tree and Photographer Shadows Crossing a Snowy Winter LandscapeAnd if you see a photographer late at night in a rest area, please let him quietly go about his work. He really doesn’t want to talk to strangers at midnight.

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To see thousands of my photographs in large file sizes for use in magazines or other printed materials or electronic media, go to my NEW website at Lee Rentz Photography or go to my Flickr Photostream.