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)

ADVENTURING TO A NEWFOUNDLAND OUTPORT

Fishing stages and colorful homes in Francois during a snowstorm

The first leg of the journey was the drive to Burgeo, a fishing village accessed by Route 480 from the Trans-Canada Highway near Stephenville. The wild and beautiful landscape was covered with deep snow, and the conifers were magically encrusted with a thick layer of hard snow so that, in places, they looked like snow elves. We kept our eyes alert for Woodland Caribou, but didn’t see any on the drive. When we reached Burgeo, we stayed at a small motel that would be convenient for catching a ferry the next morning.

View of colorful houses across rocky bay from Sandbanks Provincial Park in Burgeo, Newfoundland

We packed what we would need for the trip in two suitcases and left the rest in the car, since we couldn’t take a car on the Marine Voyager ferry. These communities have no roads and no cars, so all that is needed is a foot ferry, albeit one that can carry enough cargo to meet a small community’s daily needs. We walked up the ramp on the ice-covered boat, then descended into a room for the passengers. Comfortable seats, round portholes, and a soap opera on the television – what more could we hope for? We paid our fee of $6 per passenger, which was clearly subsidized by the government, and settled in for our sailing along the coast.

Karen Rentz on ferry Marine Voyager, which takes foot passengers and cargo between Burgeo and the outports of Grey River and Francois, leaving the dock in Burgeo, Newfoundland, Canada

Captain steering Ferry Marine Voyager, which takes foot passengers and cargo between Burgeo and the outports of Grey River and Francois, leaving the dock in Burgeo

Passenger cabin interior on ferry Marine Voyager

There were only a couple of other passengers, and they lived in the villages of Grey River and Francois (a French name Newfoundlandized to “Fran-Sway.”) We were invited up to the bridge for a front-row seat and visit with the captain, who was a lifelong resident of Francois. One of the other passengers, a younger man named Cody who owned a fishing boat, introduced himself to us as well. He was also a lifelong resident of Francois and he told us about the community and what he liked about living there. 

Hesitantly we asked the captain if he thought the ferry would be running two days later when we wanted to make our return trip, which would give us enough time to drive back to St. John’s and catch our flight back to the USA. He said this was the first time the boat had sailed for a week because of storms but that the weather looked good for our return trip. We had two nights at Francois and could enjoy ourselves. We had been watching the marine forecast every day for the past two weeks of our trip, trying to find a three-day window of weather when the ferry would be running; there were high winds and high seas every day and then finally the forecast looked good.

Waterfront with floating pancake ice at the outport of Grey River, which is snuggled along a fjord, viewed from the ferry Marine Voyager

The south coast of Newfoundland has a series of fjords, which provide sheltered locations and harbors for fishing communities. The village of Grey River was the first village we came to, and was located partway up a fjord. We motored through pancake ice and past colorful houses to the dock, where about ten people were waiting for the boat. All these people helped unload bread and beer and Amazon boxes full of the stuff a small community needs. Snowmobiles and ATVs were the transportation in town.

Unloading and transporting cargo at the outport of Grey River, which is snuggled along a fjord, viewed from the ferry Marine Voyager

Transporting cargo from dock to store by ATV at the outport of Grey River

Waterfront with glaze of sea ice at the outport of Grey River

We soon set sail again, with no new passengers – after all, who would go from Grey River to Francois in the middle of winter? The sea was rough and it started to snow, and was just about dark when we carefully navigated the narrow fjord that ends at Francois. By this time the wind was howling and the driven snow stung our exposed faces. We didn’t know where our rental place was, but the captain and another man showed us the way and took our bags for us on a snowmobile. We settled into our place for two nights, and ventured outside briefly to get a feeling for the town.

Snowstorm at night when the ferry Marine Voyager reached the outport village of Francois

Snowstorm when ferry Marine Voyager reached the public dock in the outport village of Francois, transportation of cargo by snowmobile and ATV

Karen Rentz in snowstorm at night when the ferry Marine Voyager reached Francois

Snowstorm when ferry Marine Voyager reached the public dock in Francois

We spent the next day wandering the village along its boardwalks and pathways – remember, there are no roads needed in a town with no cars or trucks. All the houses are connected by these paths. The town is small, but has Sharon’s Place, a grocery and liquor store that is open morning, afternoon, and evening, with breaks for lunch and supper. There is a church that sits above the rest of town, and a large school that currently has six students and one-and-a-half teachers. This must be one of the smallest schools in the world in terms of the number of students! But education also arrives by computer, with courses available to older students online. There is a medical clinic, but no permanent doctor in town. There is a helipad used during emergencies.

Colorful houses and fishing stages in Francois

Wooden community sidewalk in Francois, a place with no roads

Colorful houses are a feature of the town, with red and purple and turquoise tones mixed together in a delightful jumble. In winter some are occupied and some are not, with some people leaving for part of the year for jobs. There are stages along the waterfront: small buildings on stilts where fishermen stored gear and later processed the catch. These are a distinctive and wonderful feature of all the Newfoundland coastal towns.

Colorful houses and fishing stages in Francois

Colorful houses and stages along the fjord containing Francois

Public outhouse in Francois, with the slogan “I take crap from everyone!”

Shed with Moose and Caribou antlers in Francois

Fishing stage window with fishing ropes coiled inside along waterfront in Francois

Cleat and rope for docking in Francois

We walked past one house just as a lady in perhaps her late 70s was leaving the house on this snowy morning to meet for morning coffee with two other ladies who were 84 and 85 years old. We spoke with her briefly, and she told us she had lived her entire life in Francois. There were 89 people living in this little town in 2016, and we met perhaps eight of them – all of whom had lived here nearly their entire lives, except for time spent in the military or going to school. This lady was really concerned about the dwindling population of Francois.

As the snow continued to fall, we met up again with Cody from yesterday’s boat ride when he drove up on his Ski-Doo (the Newfoundland name for all snow machines) and chatted with him about the town. After graduating from the town’s school, the St. Simon & St. Jude Academy, he went to work on his father’s fishing boat. Later, he bought his own boat and now fishes for crabs, lobster, scallops, and sea cucumbers with his wife and up to five crew members.

Cody, a fisherman who has lived his whole life in Francois, and now owns his own boat harvesting scallops, lobster, crabs, and sea cucumbers

Fishing boat along colorful waterfront in Francois

Fishing gear on a boat in Francois

Fishing boat along colorful waterfront in Francois

Red building with firewood, crab traps, and a high birdhouse

Colorful houses and fishing stages in Francois

Colorful houses and fishing stages in Francois during a heavy snowstorm

Ski-Doo operator transporting stuff on a trailer on the wooden sidewalk in Francois

Fishing stages in Francois

Old fishing stage in Francois, where gear is kept, bait prepared, and fish cleaned

 Cody’s diverse fishing activity is a big change from the past, when the fishery was based upon the seemingly never-ending cod supplies. Alas, every time people think that a natural resource is unlimited, they use it up, and Newfoundland’s fishery was no exception. It was devastated by overfishing of the once common cod, a harvest made possible by technological advances utilized by both Canadian and foreign companies. In July 1992, with cod stocks down to less than 1% of historic levels, the Canadian government abruptly shut down the 500-year old cod fishery in order to try and save the fish. This instantly put 30,000 Newfoundlanders out of work and devastated local communities. In the years since some, like Cody, were able to diversify and found a path to the future. Others found a future in tourism, which is starting to take off in Newfoundland. The cod has since rebounded but the fishery is extremely small and limited compared to the good old days. Just try to get fresh cod in Newfoundland most of the year! 

A bit later we ran into another man on the boardwalk who was driving his Ski-Doo. He stopped to talk and told us that he was also a lifelong resident, but he didn’t make his living on the open ocean. He was a helicopter pilot who had worked for the Canadian Coast Guard, but now owns his own company and ferries a lot of people on remote hunting trips, mostly for Moose.

Ski-Doo operators meeting on the wooden sidewalk in Francois

Sharon’s Place, a general store, liquor store, and gathering place, with snowmobiles in Francois

Sign on St. Simon-St. Jude Academy, the public school, saying “A Clean Town is a Happy Town”

As I mentioned, the houses are scattered all around town seemingly randomly, with no clear lot boundaries. We asked one man about this, and he said that all the houses are built on Crown land, which is government land. People own their houses, but not the land under them.

We met another man driving his Ski-Doo who we had seen shoveling snow off a boat, which turned out to be his uncle’s boat. He works fishing for herring, crabs, lobster, and sea cucumbers. He was also a lifelong resident … are we beginning to see a pattern here? People are born here and live their whole lives here, though with a strong tether by ferry and by the internet and television to the larger world. When we asked Cody about his fellow citizens, he said that most everyone gets along well in town, but over time some people are moving away and the population is getting smaller.

Fishing stages in Francois during a heavy snowstorm

Fishing stage and colorful homes in Francois during a snowstorm

Fishing stages and colorful homes in Francois

Fishing stage, where gear is kept and equipment maintained and bait prepared

Fishing boat in Francois during a snowstorm

Crab pots and boat on a dock in Francois

The province of Newfoundland and Labrador has had a decades-long effort to move people away from the outports, which require huge government subsidies for ferry and helicopter transportation and education and medical care. By now, most Newfoundland outports have been abandoned, with the people voting to disband their towns and move elsewhere, but Grey River and Francois have been exceptions. In Francois, the question has come up for a vote twice over the years, but both times it was defeated (the latest in 2013) and the people remained. I understood that if the people voted to move out, the government would pay each homeowner $250,000 to compensate for the abandoned homes. It still could happen, but it is wonderful to see a few of the outports still hanging on against the tide of modernization.

I continued to photograph the buildings and waterfront and falling snow to my heart’s content on this wonderful day, when we talked to more strangers than we usually talk to in a week. Newfoundlanders are like that … they go out of their way to make visitors feel welcome, and we did.

Francois at blue hour twilight

Francois at blue hour twilight along a fjord with mountain towering above

Francois, at blue hour twilight with lights reflecting off the fjord

Colorful homes in Francois

There is even a good story that might be mostly true or wholly true about a German submarine that entered the fjord containing Francois during World War II. It came to quietly get fresh water for its tanks at a waterfall entering the sea. It was on a Saturday night and there was a dance at the community center in town; some handsome but unknown young men showed up who knew little English and who danced the night away with the local girls. The young women apparently thought that these might be Basque fishermen who often fished nearby, and didn’t realize that the men were German sailors.

Francois Bay in early morning from the ferry Marine Voyager, after leaving the quaint outport of Francois in Newfoundland

Francois Bay in morning light

West Point Light Tower at mouth of Francois Bay viewed in winter morning light from the ferry Marine Voyager

Ferry Marine Voyager smashing into waves on the open ocean between the outports of Francois and Grey River in Newfoundland

Ferry Marine Voyager smashing into waves on the open ocean between the outports of Francois and Grey River in Newfoundland

Waves from ferry Marine Voyager distorting mountain reflections in the fjord leading to the outport of Grey River

Ferry Marine Voyager passing the colorful houses and sea ice at the outport of Grey River

Ferry Marine Voyager passing mouth of the fjord leading to the outport of Grey River

Bridge and wheel on Ferry Marine Voyager near Burgeo

The next morning we prepared to leave Francois for the voyage back, and the ferry Captain came to retrieve us. The morning showed a bit of sun and good weather for an ocean trip, so we went down to the dock and prepared to leave. The trip back was stunningly beautiful, with morning sun kissing the snow-covered headlands. And we got back in time to make the long drive to St. John’s to catch our flight.

Arriving in Burgeo from Francois and Grey River outports in Newfoundland, Canada

To view more of the photographic work by Lee Rentz, go to leerentz.com, where you can see thousands of photographs and purchase a special one for your walls.