Treehuggers

I’ve been called a treehugger more than once in my life, and while I know the comments weren’t intended as such, I always take them as compliments. As a sobriquet it’s both true and false: true, because I do spontaneously hug exceptionally handsome or venerable trees; and false, because compared to the practiced professionals who scamper up and down tree boles every waking hour of their lives, my embraces are too amateurish to qualify as authentic hugging.

Sure, as a kid I would climb trees and hang from the larger limbs by my knees. We had several sturdy silver maples in our yard and I loved spending time in these leafy hideouts. But there’s more to being a treehugger than practice. I simply don’t have the body to become world-class, or even marginally proficient. To compete with the Eastern gray squirrels (Sciurus carolinensis) in my neighborhood, whose arboreal acrobatics would make a Cirque du Soleil gymnast green with envy, I would need a significantly different anatomy.

For example, I would need to lose enough weight (and height) to allow the friction created by the pressure of my paws gripping a small branch to overpower gravity’s bullying attempts to push me rudely onto the ground.

A better sense of balance would also be necessary if I were to have any success as a legitimate treehugger. I’m not saying I trip over myself on a daily basis but, as friends and family can attest, when I do fall it’s Charlie-Brown spectacular… and usually on my face.

Tree squirrels, in comparison, are masters at controlling their center of gravity. This can be attributed, at least in part, because they can hold on equally well with both hands and feet.  Here again I’m disadvantaged, and I place full blame on evolution, my DNA, and whichever hominid ancestors of mine, after climbing down from a tree on an African savannah, decided that standing upright and using feet almost exclusively for the precarious task of bipedal perambulation was a much better way to go than remaining quadrupedal.

My filed and brightly polished toenails would have to go, replaced by strong, sharp claws that could easily pierce porous bark or hook onto an uneven edge (completely impractical for someone who wears socks and sleeps under a blanket, though). Whereas humans, including me, need at least three points of attachment when climbing, this adaptation allows squirrels to secure their position with only two attachment points, and to grasp new surfaces at angles most animals would find impossible.

Most important of all, I would need feet that can pivot on a swivel joint, allowing my ankles to rotate backwards so I could hang from nearly vertical surfaces.

If I’d been born a flamboyantly fluffy-tailed rodent then maybe, just maybe, I could latch on to a wrinkle in the tree rind and hang by my toenails while enjoying a leisurely acorn snack. Alas, ’tis the fault in my stars to peer ever and enviously skyward, my feet with their simple-hinge ankles planted on the firmament at the base of the trunk, and looked down upon with curiosity and pity (I assume) from the higher-ups.

Life is better with a little Next-Door Nature—click the “subscribe”  link in the upper right-hand corner of this page and receive notifications of new posts!

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[Thanks to the photographers made their work available through the Creative Commons license: Mr.TinDC, Artful Magpie, JoeInQueens, and Jed Sheehan.  © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

R-E-S-P-E-C-T

An opossum in the snow

A Virginia opossum braves the snow to look for an early evening meal (iStock/twphotos, used with permission)

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[I’m on the road this week and looking forward to seeing some snow! With that in mind, I decided to reprint this piece from 2010. A new NDN post is in the works for next week.]

A dusting of snow always makes it easier to see who’s been out and about in the neighborhood. Bird tracks don’t provide much insight into genus and species, but opossum tracks are recognizable enough. Several of them—or maybe it was one very busy guy or gal—live along a favorite walking route of mine.

example of opossum paw printsOpossums are down with life in and around town, in part because they are the penultimate omnivorous opportunists. In addition to their “traditional” cuisine, which features insects, small vertebrate animals, wild fruits (including persimmons, a special treat), and carrion, ‘possums are known to take advantage of uncovered garbage bins (not without risk, as they often fall in and become trapped) and bird feeder spillage. They’re not shy about venturing through a pet door now and then either, especially if there’s a beckoning bowl of kibble on the other side. This can come as quite a shock—to both parties—when the homeowner wanders into the mudroom or kitchen expecting to say good morning to Garfield or Odie.

If ever there was a creature in need of a good spin-doctor, it’s North America’s only marsupial. The Aussie cousins—kangaroos, wallabies, koalas, sugar gliders, even wombats—have somehow garnered a higher charismatic ranking than poor old Didelphis virginiana.

Their long snout, gray fur, and naked tail cause many city and suburb folks to mistake them for rodents, and this may be the root of their public relations problems. I remember a wildlife center phone conversation with a woman surprised and frightened by an opossum who wandered through the pet door into her laundry room.  Eventually, I was able to calm her down a bit by convincing her she was not dealing with a freak-of-nature rat, but my attempts to help her appreciate the natural beauty standing in front of her dryer fell on deaf ears.

Startled Woman: I’m sorry, but I can’t even stand to look at him… he’s just so UGLY!

Indignant Wildlife Biologist (that would be me): Well, ma’am, he’s probably thinking the same thing about you!

Not one of my finest Wildlife Hot-Line moments, I know, but the words were tumbling off of my tongue before I had a chance to bite it. I happen to find opossums quite handsome. Still, there’s no denying that rodent resemblance. If you are mouse-and-rat adverse you’ll probably never come to think of ‘possums as pretty.

There’s another problem—it’s a common misconception that ‘possums are clumsy, dirty, and not all that bright, with poor vision and hearing to boot.

Don’t believe it.

Personally, I think any species that’s managed to survive relatively unchanged since the Cretaceous deserves a little more credit. Modern humans arrived on the scene nearly 90 million years later, so perhaps we should be a little more respectful of our elders.

Opossums are actually quite clean. They carefully groom themselves during and after eating—even the babies. When it comes to the acuity of their senses, common knowledge has it all wrong. These marsupials have excellent hearing and can easily detect the rustling of prey hidden under dry leaves or tree bark. A wildlife rehabilitator friend who works extensively with opossums tells me they evolved with a focus on olfactory sensitivity and, as a result, have an extraordinary sense of smell. Their sight is about average for mammals, but because they are primarily nocturnal, their eyes are adapted to working under low-light conditions. Our daytime is their night and, as a result, they can appear rather dazed and confused in sunlight.

Kind of like me when I’m up past my bedtime.

Life is better with a little Next-Door Nature—click the “subscribe”  link in the upper right-hand corner of this page and receive notifications of new posts!

 

© 2010 Next-Door Nature — no reprints without written permission from the author.

Scary-smart

Halloween raven

Ravens populate the mythology of many cultures throughout the northern hemisphere  (Photo: John North/iStockphoto, Used with permission).

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[I’ve been frighteningly busy throughout the month of October, so I’m reprinting this post from October 2011 in honor of Halloween, and ravens.]

Fright-night is lurking just around the corner. Frankensteins, mummies, zombies, ghosts, and golems will soon leave their lairs to roam freely through our cities and suburbs, searching for something to eat. Butterfingers, Baby Ruths, and brains—oh my!

poe's ravenReanimated but mindless creatures? HA! They don’t scare me. It’s the ones I’m not so sure I could outsmart that give me nightmares. You know… Hannibal Lecter. Patrick Bateman. Brilliant but mad scientists. Shape-shifters, tricksters, and ravens.

That’s right—it’s Poe’s gently rapping, tap-tap-tapping apparition, the common raven (Corvus corax), that keeps me up at night. Similar in appearance to the American crow (Corvus brachyrhynchos), but larger and more slender with a wedge-shaped tail and a heavy, arched beak—a santoku blade to the crow’s steak knife.

Now, understand that I’m not implying they’re evil. It’s just that there’s definitely something spooky about a massive, inky bird with a genius IQ and an inclination towards… exploiting opportunities, shall we say.  Humans have long considered these birds both charismatic and ominous, fascinating and frightening. Spread across much of the northern hemisphere, ravens have stained the mythologies of native people Valkyries by Emil Doeplerthroughout their range. In Scandinavian cultures, this feathered carrion-eater was associated with war, blood, and corpses and their Valkyries—goddesses who decide which warriors will die in battle and who will be granted an afterlife in Valhalla—often were accompanied by ravens. The Celts made a connection between ravens, war, and death as well; true to their inherent interest in metaphysics, though, they also credited these birds with the ability to see the future, to move freely between worlds and, oddly enough, to play chess (rook is the common name for Corvus frugilegus, a European member of the raven-crow clan).

Mythology aside, ravens have been judged by humans to be among the smartest of all birds. That may be damning them with too-faint praise. Various studies in and out of the lab have tested researchers intelligence and creativity while they attempt to test the raven’s problem-solving skills. The jury’s still out on which party finds these efforts more enlightening. Ravens have been observed applying an understanding of cause-and-effect to the problem of filling an empty stomach—they learn to associate the sound of a rifle being fired during hunting season with the presence of a carcass (similarly loud sounds are ignored). Not content to simply wait for a scavenging opportunity, ravens will work in pairs or even larger teams, using a distraction strategy to separate adult birds and mammals from their vulnerable children, to gang up on prey too large for a single bird to overwhelm, or to defend resources and territory against neighboring gangs. Nature, it has been said, is red in tooth and claw, and ravens are definitely a part of that gruesome heritage.

There’s more to the story, of course—isn’t there always? Ravens are a threat to any number of wild youngsters, but they are devoted parents to their own offspring, who remain dependent for longer than many other bird babies. Both male and female are involved in parenting and are thought to mate for life.

Ravens aren’t as social as crows—they would prefer to go trick-or-treating alone or in pairs than in a mob—but they aren’t loners in the stereotypical serial-killer sense. During winter months they will form a flock, a.k.a. an unkindness (who comes up with these names?!), to find food during daylight hours and stay warm at night.

raven playing with the windOne very appealing characteristic is their sense of fun. Ravens are audacious, acrobatic flyers who take obvious pleasure in practicing dives, rolls, and loops, or even flying upside-down. I’ve personally watched ravens play with the wind blasting up the face of a cliff or a tall building, a sight that never fails to make me long for wings of my own. A favorite game, particularly among young ravens, involves climbing high in the sky holding some object, dropping it, and then racing gravity to catch it midair.

I also learned that here in North America, ravens have been assigned a very different mythological role than in Europe. Pacific Northwest legend has it they take a kind of noblesse oblige attitude toward the human race. Grandfather Raven is portrayed as a devilish philanthrope, a Robin Hood figure who stole the Sun, Moon, Stars, Fire, Water, and even Salmon from various deities and gave them to the people. How would you like to find those treats in your goody bag on Halloween?

Perhaps ravens, like so many scapegoats before them, have been unfairly vilified.  We should never forget that the job of predators and scavengers is thankless, but a crucial component of healthy ecosystems. French author Andre Gide may have said it best, “There are very few monsters who warrant the fear we have of them.” I think it’s time to change my thinking.  From this point forward, I’m going to dream of playful, benevolent ravens and be frightened nevermore.

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© 2011 Next-Door Nature— no reprints without written permission from the author. Thanks to Ian Burt (Poe’s raven) and Ingrid Taylar (raven playing on the wind) for making their photographs available via a Creative Commons license. Walkyrien by Emil Doepler is in the public domain.

Wingsuit

Southern flying squirrel (Glaucomys volans), © 2014 Peter Harrill, used with permission

Is there any non-human skill people covet more passionately than the ability to fly?

Understandably, early aviation experiments centered around mimicry of birds, complete with flapping arms that were usually covered in feathers. The Greek legend of Daedalus and Icarus is a familiar example, but plumage continued to be part of the trial-and-error approach through the first years of the 19th century, when a tailor named Albrecht Berblinger constructed an ornithopter and then took an ill-fated plunge into the Danube. Those daring young men with their dreams of flying machines… they just didn’t understand the concepts of thrust, lift, and drag, and they couldn’t let go of the idea that soaring requires feathers.

I guess Saturday mornings with Rocky and Bullwinkle were not a part of their childhood.

Skip ahead in the history books about two hundred years, during which heavier-than-air flight went from foolish fantasy to fleetingly airborne, to semi-reliably aloft, to acrobatic enough to decide the outcome of a World War, to commonplace as ~30,000 commercial flights per day in the U.S. in 2017.

And yet…

Aviation advancements and inventions during the greater part of the industrial age were about balloons and dirigibles and planes, i.e., aircraft; human beings remained firmly planted on terra firma unless they could climb inside or hang from some kind of apparatus.

It’s hard to point to a specific aeronautic adventurer as the first to see a flying squirrel, recognized the similarities with their fellow mammal, connected the dots, and think, “Eureka! A wingsuit!” But no one lucky enough to have seen one of these big-eyed nocturnal windsurfers could fail to notice the resemblance to the modern flying suits that have finally allowed human beings to fly free as a bird squirrel, unencumbered by gondola, scaffolding, or fuselage.

Of course, strictly speaking flying squirrels don’t really fly, and neither do the people wearing a wingsuit.

They glide.

The wingsuit mimics a flying squirrel’s patagium—loose folds of skin that span the space between forelimb wrist and hindlimb ankle on either side of the body. Spreading those limbs into a jumping jack X, the furry membranes stretch into a rectangular shape that allows the tiny BASE* jumpers to propel themselves into the air and then slide down the sky at a 30-40 degree angle controlled fall.

© 2008 Steve Collins, used with permission

A long, flat tail is critical for controlling that fall. Serving as a rudder, it allowing 90 degree turns around mid-flight obstacles. The tail is used for landing, too; on the approach, the tail is raised to an upright position while, at the same time, all four limbs move forward to form a kind of patagium parachute. Together, these actions create enough drag to tip the animal’s head and body up as it prepares for impact with a tree trunk or branches, a bird feeder, or a building.

Northern flying squirrel (Glaucomys sabrinus) © 2015 Jukka Jantunen, used with permission

The New World is home to three species of rodent flyboys and flygirls: Northern (Glaucomys sabrinus); the recently differentiated and designated Humboldt’s (G oregonensis); and Southern (G volans). There’s some range overlap between Northerns and Southerns, but the two species are relatively easy to distinguish. Northerns are larger, but the belly of the beasts provides a much more notable difference; the underside of a Southern flying squirrel is creamy white, while Northern flying squirrels are beige below with darker roots.

Humboldt’s flying squirrel

There’s range overlap between Northerns (found from Alaska to Nova Scotia down to Utah and North Carolina) and Humboldts’ (whose limit their travels from British Columbia down into southern California) as well. However, the two are close enough in physical appearance and behavior that it took an examination of their DNA before scientists realized earlier this year (May 2017) that they were looking at not one species, but two. Humboldts’ have been described as smaller and darker than Northerns, but the fact that it took so long for the former to be recognized as distinctive (Southerns were first described in 1758, Northerns in 1801) suggests to me that one would have to do a mighty up-close-and-personal examination to make a positive ID.

All three varieties of Glaucomys have one important feature in common: they’re more risk-averse than you might have assumed. Riding the wind wearing a wingsuit is a dangerous activity for humans — one severe injury for every 500 jumps, according to one study, despite advances in materials, design, and training — but it’s just another day in the life of a flying squirrel. That’s not to imply they never miscalculate a distance, or botch a landing, or are immune from injury (or worse), but they do have concerns beyond thrust, lift, and drag, or changes in wind speed and direction.

Which is why, immediately after sticking the landing, a flying squirrel will scurry quickly to their nest hole, or the other side of the tree, or at least toward a deeper shadow. BASE jumpers and skydivers rarely have worry about avoiding predators waiting in the wings.

[Thanks to the photographers who granted permission to use their photos, and to those who made their work available through the Creative Commons license: Richard Schneider, and Barbogast. The painting of Icarus and Daedalus is by Charles Paul Landon, and the drawing of a New World flying squirrel is by Charles Henry Dessalines d’Orbigny, currently in the University of Washington’s Freshwater and Marine Image Bank; both images are in the public domain. © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

*BASE is the acronym that stands for the four categories of fixed objects from which one can jump: building, antenna, span (bridge), and Earth (cliffs).

Sentry duty

blue jay

Blue jays keep a close watch on their neighborhood (Photo: Rick Leche, CCL).

[This post was first published on Feb 12, 2011.]

JAY!  JAY!  JAY!

Uh oh. I’ve been spotted, and the guards have ratted me out.

HALT! Who goes there?

Thought you could slip past, did you? Not on my watch. Hey everybody—look!

LOOK! OVER THERE!

Steller's jay

Steller’s jay (Photo: Allan D. Wilson, CCL).

Every non-human ear in the neighborhood takes note. It feels a bit like being caught at an awkward moment by the paparazzi. But I don’t take it personally. I know everyone who wanders past is subject to the same protocol—people, cats and dogs, hawks, snakes, you name it. Jays take sentry duty seriously. Any real or imagined threat to the forest citizenry is duly noted and announced.

western scrub jay

Western scrub jay (Photo: Len Blumin, CCL).

Jays are part of a large family. Their Corvidae cousins include gray jays, nutcrackers, crows, ravens, and magpies, as well as some species we’re not that familiar with in North America–choughs, treepies, and jackdaws. In the Americas alone there are over 30 different species christened with some variation of the “jay” brand. The five scrub jays (Aphelocoma spp.) and the pinyon jay (Gymnorhinus cyanocephalus) closely favor one another, but two members of the North American branch have made striking and unique sartorial choices. Once you’ve seen a Steller’s jay (Cyanocitta stelleri) or a blue jay (Cyanocitta cristata), you’ll never mistake them for any other bird.

Florida scrub jay

Florida scrub jay (Photo: B. Walker, CCL).

Of course, they’re not really blue. It’s just a trick of the light called a schemochrome. If you find a blue jay feather you can watch the color disappear and reappear as you roll the shaft between your fingers, changing it’s position relative to the sun. These forest defenders are high-tech.

When they’re not spying on everyone, jays pitch in to give the next generation of trees a head start. Okay, that’s probably an accidental community service. Jays bury acorns and then fail to use them all at snack time. The seeds germinate and—poof!—you’ve got a new oak tree. If society benefits from your actions, intentional or not, shouldn’t you still get some credit?

 

piñon jay

Pinyon jay (Photo: Tony Randell, CCL).

Despite their public service efforts, jays have a reputation as bad birds. Maybe it’s the black mask some of them wear. More likely, it’s the abuse of power so often attributed to their ranks. Eye-witnesses tell of raids on the nests of other birds for eggs and hatchlings, but one extensive study of blue jay feeding behavior found only 1% of these feathered neighbors had evidence of eggs or birds in their stomachs. You’ll also hear stories of jays who trick fellow backyard residents into leaving the feeder by mimicking hawk calls. Now, I can’t deny that some bullying does occur. Think of it as the price of protection, if you must. But judge not, lest ye be judged. Keep in mind that both Steller’s and blue jays have complex social systems and tight family bonds.

Birds, like people, are rarely all good or bad. Your perception of how the scale tips often depends on your point of view. Life isn’t always black and white, or even shades of gray. Sometimes, it’s not even blue.

© 2011 Next-Door Nature— no reprints without written permission from the author.

Long-stemmed

Daddy longlegs are the jazz cats of the arachnid world!

This realization came to me as I watched a single backlit note poised on a broken music staff bebop across the asphalt path in front of me. A soundtrack of jazz piano greats immediately began to play in my head — Willie “The Lion” Smith, Thomas “Fats” Waller, Art Tatum, Thelonious Monk, and Dave Brubeck, to name but a few. Chill dudes whose spider-like fingers strode, slid, bounced, and stomped across the keys.

Jazz has evolved and diverged from it’s start in the late 19th century as  ragtime and Dixieland into a genre so diverse it can be difficult to define, or even to list all the variations: Swing, Cool, West Coast, Modal, Free, Fusion, Funk, Cu-Bop, Post-Bop, etc.

The harvestmen, as daddy longlegs are also known (that even sounds like a 1950s jazz band, doesn’t it?) have an even longer and more impressive history. They’re a vast, improvisational set that spans millions of years and many taxonomic octaves, with over 6,500 named species worldwide (experts estimate there may actually be more than 10,000). And while not all the players in this big band have long legs, the ones who hangout in my neighborhood— eastern harvestmen (Leiobunum vittatum)— are definitely long-stemmed.

These invertebrate daddy-o’s are arachnids but they are NOT spiders; they’re more closely related to mites and scorpions.  Harvestmen don’t have a spider’s tiny waist… or venom… or silk (so no webs)… and they have only two eyes instead of eight.

Jazz musicians need to maintain their instruments to get the best sound; piano hammers need to be voiced, strings tuned, reeds moistened and valves lubricated.  Daddy longlegs are similarly serious about the tools of their trade, cleaning each leg after a meal by threading them through the pincers by their mouths.

Harvestmen are a gregarious lot who periodically congregate in the hundreds or even thousands. Scientists have suggested these spontaneous jam sessions might occur in response to climatic conditions or provide some protection against predators… but it’s pretty clear they aren’t making music (that can be detected by the human ear, anyway).

Members of Order Opiliones are exceptional even among arachnids. They can swallow small pieces of solid food, whereas their cousins are limited to a liquid diet. Conversely, daddy longlegs sip oxygen through their legs into a trachea, while other arachnids respirate through a gas exchange organ called a book lung. That’s probably just a warm-up, though. Like jazz, daddy longlegs are both familiar and mysterious. Little research has been done on these species… and who can say why? Maybe they’re a bit too avant garde to have a large fan base among researchers.

Or it could be the hours they keep and the dives they frequent. See, eastern harvestmen have more in common with jazz pianists than an impressive hand (or leg) span. Say what you will about the pleasures of sitting outside at a warm summer evening festival, lounging on a blanket in the grass while listening to a live performance — you’ll hear no argument from me. But to my mind, jazz is an urban art form, and the smokin’ hot licks happen in basement clubs. An intimate corner, low lights, insulated from street noise, maybe just a little damp…

Now that the kind of gig daddy longlegs’ dig.

 

[Thanks to the following photographers for making their work available through the Creative Commons license: Rob Swatski, Leslie Bliss, Rob SwatskiLuis Fernández Garcia, and schizoform.  © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

Still Life

Great blue heron

The great blue heron is a patient angler.

[I’m working on new essays this week so I hope you’ll enjoy this reposting from March 26, 2011]

Racing past a nearby pond, I mistook the bird for an art installation.

I realized my error quickly enough once I downshifted. Then again, there’s just something so painterly about a great blue heron (Ardea herodias). The graceful, sinuous lines; the aqueous blues and grays; the plumage, evocative as a brush stroke. The unhurried disposition that creates a pose of every posture. The stippled scene was realism and impressionism all at once.

Slow, prehistoric wing-beats call to mind the cave paintings of Lascaux and Altamira. The great blue is one of the more easily identified birds in flight, partly due to its size—a 6-foot wingspan is hard to miss—and partly because of its silhouette, reminiscent of a textbook pterodactyl: neck folded back on itself in a compressed S; a contrail of long, slender legs.

Statuesque as an adult, the stalk-and-strike hunter spends much of its life standing still as stone.  Balanced as bronze armature, this is a kinetic sculpture that moves imperceptibly, and yet, as you watch… you can feel the potential energy of that cocked, cursive neck building in your own musculature, grown taut with anticipation.

Patience personified…

waiting…

waiting…

waiting…

and THEN

…the spring detonates with blinding speed, blasting the javelin bill through the water’s surface and into the target!

The spear is dragged back from the depths as a squirming fish-kabob. Or, perhaps, a canapé of frog, salamander, crab, or crawdad… would you prefer a vole, garter snake, duckling, or a dragonfly. Heron menus include far more than seafood.

On occasion, large prey will be consumed bite by bite. A tedious process and, as every angler knows, if you want to increase your catch you need to keep your line in the water. So, more often, there’s a flip of feathered head and neck, then dinner is swallowed whole.

Or not. That narrow neck can accommodate a surprisingly wide load, but in the hurry to put the catch in the creel, herons have been known to choke on a too-big meal.

 

 

I know the feeling. I gobble down the items on my to-do list—even tasks like “take a walk.” I channel surf when I should take the time to savor the canvas before me. Taking a deep breath, I tried to quiet my mind, and settled down to watch… and wait.  Dining, fishing, or appreciating a living, breathing work of art—these are pastimes that can’t be rushed.

 

[Thanks to the following photographers for making their work available through the Creative Commons license: S Pisharam and Len Blumin. Blumin, who is responsible for the “catfish dinner” series, reports that in this particular heron’s eyes were NOT bigger than its stomach, or its throat, and it lived to fish another day. © 2011 Next-Door Nature. Reprints welcomed with written permission from the author.]

Vert-de-Gris

Cope’s gray treefrog on a pepper plant. Photo: Alan Howell © 2017, Star Path Images, Used with Permission.

It isn’t easy being green. Kermit the Frog said it, so you know it has to be true.

He’s always seemed a reluctant celebrity, so my guess is that being the most famous Muppet-amphibian on the planet isn’t always a picnic. I wonder whether life would be a little less stressful if, like some of his cousins, Kermit could change from green to another color when he’d rather not be so conspicuous.

North American gray treefrogs know how to be seen and when to blend into their surrounding, shifting the spectrum from bright emerald to peridot, to gold, copper, platinum, silver, and even gunmetal. Since the places they hang out — trees and shrubs in woodlands, meadows, prairies, swamps, suburbs, and cities — tend toward palettes awash with green and gray hues, these arboreal amphibians can keep their sartorial choices simple. 

What looks like a costume change is actually a rather high-tech, cellular-level special effect created by chromatophores. These pigment-containing and light-reflecting cells, or groups of cells, are present in the skin of certain frogs, as well as some reptiles (including chameleons), cephalopods (such as octopi), fish, and crustaceans. Mammals and birds, on the other hand, have melanocytes, a different class of cells for coloration.

Chromatophores are classified based on their hue under white light:

  • melanophores (black/brown)
  • cyanophores (blue)
  • erythrophores (red)
  • xanthophores (yellow)
  • leucophores (white)
  • iridophores (reflective or iridescent)

The process, known as physiological color change, can be controlled by hormones, neurons, or both. Most studies have focused primarily on melanophores because they are the darkest and, therefore, the most visible. When pigment inside the chromatophores disperses throughout cell the skin appears to darken; when pigment aggregates in cells the skin appears to lighten. Either way, you’ve got an amazing makeover, or a convincing disguise, in no time flat! 

There’s even more to the gray treefrog’s ability to assume an alter-ego than meets the eye —what appears to be a single species is actually two very close relatives: Hyla versicolor, aka Eastern, although there’s a long list of pseudonyms from which to choose (there are more ways to hide than blending into the substrate); and Hyla chrysoscelis, aka Cope’s (which also has a couple of nicknames but not as many as H. versicolor).

Cope’s and Eastern are equally skilled at clinging to and climbing slick surfaces using large toe pads that secrete mucous, creating surface tension. It’s not uncommon to find one plastered against a window pane (allowing for an interesting view of their nether-regions). Both species prefer a diet of small insects, spiders, and snails. Both hibernate under leaves, bark, or rocks. Well, “hibernate” sounds a lot more cozy than the reality… which is that their bodies pretty much freeze and their lungs, heart, brain, and other organs stop working until they thaw out and reanimate in the spring. It’s a pretty nifty chemical trick, on par with being able to transform your complexion at will. 

Kermit has an unmistakable personal brand, but distinguishing H. versicolor from H. chrysocelis visually is just about impossible. Both Eastern and Cope’s are relatively small (1.5—2.0 in/3.5—5 cm), and the adults are often mistaken for younglings. Both wear a sweep of bright citrus-orange along the inseam of their hind legs (a signature shade is all the rage, you know).  Females of both species are usually (but not always) larger, with a ladylike white throat. During the breeding season, males have a macho (make that hipster, since it resembles a beard) black, gray, or brown throat. Guys sing. Gals swoon, but don’t sing along.

The ranges of these two species overlap, but Cope’s are more widely distributed. If you find a gray treefrog in North Carolina or Georgia, you can be reasonably certain it’s a Cope’s, but if you’re in Iowa or Pennsylvania, all bets are off. The only risk-free way to know for sure is to do a DNA test — Cope’s are a diploid species, meaning they have two sets of chromosomes, one from each parent (for a total of 24); Easterns are a tetraploid species, meaning they have four sets of chromosomes (for a total of 48).

Now, some frog call connoisseurs claim they can detect variations in breeding calls, and that Cope’s treefrogs have a faster and slightly higher-pitched trill than Easterns. But the call rates of both species change with ambient temperature… so color me skeptical.

[Postscript:  What kind of frog is Kermit? While I’ve never found a definitive answer to this question, I always assumed that because he was created/discovered by Jim Henson, he was probably Hyla muppetalis or Rana hensonii… something like that. However, in 2015 Brian Kubicki of the Costa Rican Amphibian Research Center discovered a frog who, if not the same species, must at least be a first cousin, or possibly Kermit’s doppleganger.]

Diane’s bare-hearted glass frog (Hyalinobatrachium dianae). Photo: © Brian Kubicki, Costa Rican Amphibian Research Center, Used with Permission

[Thanks to the photographers who granted permission to use their photos, and to those who made their work available through the Creative Commons license: Dave Huth(composite of color variations), , Chiswick Chap & CheChe, (melanophores schematic), Alan Wolf, Andrew Hoffman, and Douglas Mills© 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]