The Campus Hibernaculum

I close my eyes and listen for their quiet rustling.  Long, tube-like bodies create a distinct sliding sound, as they franticly zip through the leaf litter in a frenzied search for love.  Nothing is quite like the sound of a garter snake navigating its way through the understory.  It’s softer than the robin ruffling for insects in the substrate.  It’s smoother than the scampering of a chipmunk dashing along a log.  It persists as the gentle breeze tappers away into near silence.  Silence, except for that deliberate sliding.  Few sounds let me know instantly who is nearby, but just hearing doesn't always mean I’ll find my garter.  They are clever, secretive, and quick.  Patience, however, is often rewarded with the face of a skinny, striped reptile periscoping up at me through the tangles of vegetation.

Spot the garter snake.

It amazes me what people will miss when they aren't paying attention.  I am often stunned how oblivious folks can be to the wildlife and nature right in front of them.  I admit, some creatures can be a real challenge to spot.  I’ve stared in vain at the tangles of vines and foliage where a dozen other birders claimed a saw-whet owl was roosting.  My friend Carl Brune often stops to check out amphibians that I had mistaken for a lump of dirt or a stick.  Many animals are small, inconspicuous, secretive, camouflaged, or nocturnal.  Wildlife searching is a challenge and an adventure for these very reasons.  Animals aren't usually easy to find, and that’s what makes looking for them so much fun.  

On special and unique occasions, however, wildlife isn't hard to find.  Obvious examples include local backyard birds, squirrels, and deer.  There is beauty in the abundance and resilience of these creatures, but even I stop looking at every gray squirrel or American robin that crosses my path.  It’s a shame, but few are going to get inspired about nature and conservation from the animals they see every day.  Backyard wildlife gets written off as a nuisance, closing the link to a world beyond our doorstep.  It takes the unexpected to ignite curiosity.  But there again, lies the crux of the issue.  Folks don't know to be looking, and so they don't see what is right in front of them.  

I have watched dumbfounded, as groups of hikers overlooked a massive female snapping turtle, never realizing that the oddly ridged stone they were hopping over wasn't a stone at all.  I have seen others look right through the intense gaze of the local barred owl—never distinguishing her silhouette from her hemlock perch.  When possible, I try to bridge the gap, bringing to light what others have missed.  It is a delight to see joy spread across their faces as some new creature materializes before them.  “I never would have noticed that on my own,” is the usual response.  It breaks my heart to think of all the lost opportunities, because I know how powerful a connection to a wild creature can be.  It only takes one introduction to the natural world to spark a passion that can change an entire world view.

The campus hibernaculum.

In our modern, developed society, these introductions have become few and far between.  Most folks imagine the wonders of nature as something only read about in books or filmed by the BBC.  This is an unfortunate misinterpretation.  More often than most people realize, unfamiliar and fascinating creatures turn up where no sane biologist would start their search.  Like the wildflower pushing up through a sidewalk crack, animals find a way to make a living right next door.  

Had I known about the campus hibernaculum before coming to Ohio University, I would have had no question in my mind what college was right for me.  Tucked away on a vegetated hillside, smack dab in the center of campus, sits a refuge for dozens of scaly serpents.  Eastern garter snakes (Thamnophis sirtalis) and northern water snakes (Nerodia sipedon) have taken up residence in the rock face.  Every spring, they emerge to bask in the shrubbery along a frequently-used footpath.  Hundreds of students and professors pass within inches of the snakes every day without ever realizing it.  To calm the ophidiophobes among you, these are harmless species, growing to only a few feet in length.

The term hibernaculum refers to a location where reptiles overwinter.  A well-drained cavity within the rocks provides a hiding place during the harshest months of the year.  Here, the animals can slow down their metabolisms, reducing their energy use and need to feed. These hibernacula are often found on southward facing slopes, providing suitable basking spots in late winter and early spring.  I have observed as many as ten snakes out basking in February, with snow still on the ground.  Their tan and yellow stripes make for excellent camouflage against the forest floor.  It's that tell-tail sliding that gives them away. 

Garter snakes and water snakes exhibit a fascinating strategy of reproduction.  Males begin to patrol the leaf litter as soon as the weather peaks into the 50s.  Once a female emerges from the hibernaculum, males quickly swarm her, competing to be her mate.  Like a scene straight out of Indiana Jones, these "mating balls" usually consists of one female and up to several dozen males.  Once the males have locked onto the female's chemical cues, nothing can persuade them to leave her side.  They entwine themselves with her body and use their chins to caress her head.  The excitement may even frighten off the much larger female (up to three times the size of a male), in which case the frantic serpentine suitors will dart quickly after her.  

A garter snake mating ball.  Here two males (left) compete to mate with a large female (back right).

When breeding finally takes place, the female will develop the eggs inside her body for one hundred days. Garter snakes are ovoviviparous, meaning they give birth to live young.  Around twenty babies are born in late summer and fall, to which no maternal care is given. The neonate garters can fend for themselves from birth.  

While focused solely on reproduction, garter snakes can be exceedingly docile towards humans.  The males become so fixated on the task at hand, that they won't protest being plucked from the ground by a curious hand.  They may musk, but will rarely bite during this season of love-making.  Early spring, just after the snakes have emerged from the hibernaculum, can be the best time of year to admire these legless reptiles.  It is wonderful to see other folks taking stock of the nature right outside.  I have seen families with little kids exploring the shrubbery for snakes.  Professors with cameras in hand often peruse the earth as they pass by.  I have even come across other students interpreting to a huddled group of peers, watersnake in hand.  It's amazing what you will see when you take the time to look.  

Tigers by the Tail

“That’s no spotted salamander” I thought as I looked down at the large, blotched amphibian clambering its way over the paved road.  For one thing, the salamander’s head was enormous with drooping jowls that turned its expression into a grimace.  It looked so top-heavy, that I was surprised the animal didn't tumble over itself with each step.  Its sleek body was a deep purplish-brown with rich caramel spots that extended from its snout down the length of its huge, rudder-shaped tail.  As I gingerly picked the salamander up off the road, the tip’s of its fingers gripped my hand with what felt like tiny claws (not true claws of course, just hardened keratin on the finger tips)—a tiger of a salamander indeed.  

I was back home in northeastern Ohio for the 2018 Ohio Biological Survey Conference held at the Cleveland Museum of Natural History.  It was nostalgic to walk the halls lined with the same taxidermied dioramas and fossil bones that I first fell in love with as a young boy.  Growing up, my grandparents would take my brothers and I to the "Dinosaur Museum" every chance we got.  It’s only a short 30 minute drive from where we lived, but to us, a trip to the natural history museum felt like a week long excursion.  We spent hours staring at the displays, imagining worlds long past.  We traveled to space, to the rainforest, to the Cretaceous extinction—admiring everything from trilobites to terror birds.  

After presenting our box turtle poster and listening to a day of talks, I was eager to get out into the rain and do some herping.  As I considered searching a nearby spot for unisexual ambystomids, I overheard some folks talking about eastern tiger salamanders (Ambystoma tigrinum). Of course I joined the conversation. Tiger salamanders are one of those species that first sparked my interest in Ohio's amphibians. I had dreamed of finding one for years, but I never knew where to look.  My fellow natural history enthusiasts were kind enough to share some possible locations.  The perks of building connections.

Later that night, my dad and I donned our rain gear and headlamps, and set out for northwestern Ohio. Back when I was just a kid, we saw our very first salamander migration together.  It feels like a lifetime ago now.  From humble beginnings, we eventually traveled all over northern Ohio in search of different herps and birds.  My dad is more of a hiker than a wildlife watcher, but he is always interested to see what new slimy or scaly creature I've pulled out of the muck.  It had been some time since the two of us went herping together; it was nice to get back out in the field with him.  

As we arrived at our destination, I was glad to see the temperature had jumped up to the mid-40s.  Still chilly, but plenty warm enough for amphibians to start moving.  As we hiked towards the vernal pools, the rain turned the boardwalk's already slick surface into a slip n' slide.  Shuffling carefully along, I heard the first frog of the night.  Like fingers scrapping across a comb, the caller was unmistakable: a western chorus frog (Pseudacris triseriata).  I had only seen one western chorus frog before and was hopeful the night would produce a second.  

Chorus frogs and tiger salamanders breed in the temporary vernal pools associated with most early breeding amphibians.  Tigers, however, prefer deeper, more permanent bodies of water compared to most mole salamanders, and will even breed in fish-free ponds.  We scanned the shallows of the flooded woodland, trying to pick out eyeshine or a swimming silhouette.  No frogs, no salamanders, no egg masses.  The pools appeared to be devoid of breeding amphibians.  I decided to switch tactics and try our luck road cruising.

Immediately, we started to see amphibians.  As I stopped to move wood frogs and spring peepers off the road, one little, tan frog stood out.  It was slightly smaller than the average peeper, with three distinct vertical stripes running down its back.  Our chorus frog, what luck!  Western chorus frogs are some of the earliest breeders in Ohio, and can be found across much of the state and the US as a whole.  They are usually less abundant than spring peepers, and are more often heard than seen.  We found only one the entire night.

Like the western chorus frog, eastern tiger salamanders are a widely distributed species. They occur across western Ohio (and on Kelley's island) and their range extends from the east coast to the edge of the great plains.  Close relatives of the eastern tiger salamander (like the barred and the California tiger salamander) can be found throughout the west. During the non-breeding season, adults secret away in underground burrows in forest and prairie habitats. They are the largest terrestrial salamander species in the state, and in some cases, exceed 10 inches in total length.  As larvae, tigers are notoriously cannibalistic, readily consuming their smaller siblings.  

After snapping some shots of the chorus frog, we cruised up our first tiger of the evening. My shout of delight was the signal to pull over.  "It's huge!" my dad commented, as we knelt down to photograph our find.  Crouching on my hands and knees in the pouring rain, he scoffed at my indifference to the cold and wet whenever amphibians are involved.  The rain didn't bother me for good reason.  This tiger salamander was easily the largest mole salamander I had ever seen, probably 6 or 7 inches in length. It froze in the light of my headlamp, blinking its round, golden eyes in bewilderment.  After realizing we weren't about to eat him, the salamander resumed its trek towards the vernal pools.

I was glad to get some decent pictures on the road, because the tiger refused to cooperate when I placed it on natural substrate.  Despite my best efforts, I couldn't convince the stubborn salamander to lift its enormous head.  Splaying its legs out awkwardly to the sides, it squirmed and buried its snout under pine needless and other woody debris.  I tried for ages to get a good angle in the pouring rain, risking my camera for a photo I never got.  Ah well.  That's the way it goes sometimes.  We found three adult tigers by the end of the night, none of which allowed for my glamor shot.  

Note the split lip on this female.

The second tiger salamander we discovered was even larger than the first.  Its tail alone must have exceeded 5 inches in length.  Examining each tiger closely, I noticed how beat up they looked.  Old scars and battle wounds covered their spotted bodies—a chunk out of the tail here or a split lip there.  Contending with shrews and voles is the price these amphibians pay for living inside mammal burrows.  Rodents and shrews can be quite the adversaries, even for a salamander so large.  Noxious skin secretions make mole salamanders unpalatable to most mammalian predators, but predation rates can still be high.

I moved each of the tiger salamanders across the road in the direction they had been heading.  Traffic was light, but we still saw one crushed salamander and several dead peepers and wood frogs.  These slow-moving amphibians are completely defenseless when it comes to roadways and vehicles.  Helping a few to safely make it across the road was the best we could do.  As the rains dwindled, we headed for home.  With luck, the nearby vernal pools would soon be full of calling frogs, courting salamanders, and egg masses.  I hoped to return soon to witness their breeding first hand.

Tale of Two Salamanders

I held tight to my camera as the truck lurched forward, front tires plunging into several inches of mucky water.  Carl and I had chuckled at the prominent yellow signs, declaring “road may flood,” on the way in.  With each pass around the forested wetland, the water had risen by several inches, sinking our tires further and further into the oily blackness.  With the road now well under a foot of water, I was beginning to question our bravado.  “What is that!?” Carl exclaimed as something furry and brown half scurried, half swam out from under our advancing vehicle.  It was a muskrat, swimming over the two lanes like this was just another stream.  As the aquatic rodent dove under the surface, its body undulated, revealing a long, flattened rat-like tail.  

Getting stuck on some back country road an hour south of Athens wasn't on my to-do list for the night. Thankfully, Carl's trusty four-wheel drive pickup rumbled heartily through the deepest stretches of water. I hadn't anticipated how quickly the surrounding wetlands would overflow, turning the entire landscape into one big vernal pool.  As the rains picked up, the light traffic dropped to about zero.  This was good for migrating amphibians and other water-logged wildlife, but I wondered how long it would be before anyone noticed us if we did get stranded out here.

Cambarus bartonii cavatus an undescribed species.  Note the dozens of babies under its tail.

Reaching higher ground, we spotted something small and shiny crawling lamely over the asphalt.  Expecting an injured amphibian, I was instead met with the largest crayfish I had ever seen.  This land-dwelling crustacean (Cambarus bartonii cavatus, evidently an undescribed species) was a good sign for the mole salamanders we were looking for.  Crayfish dig extensive burrows in the surrounding woodlands, lawns, and agricultural fields, providing fossorial amphibians with a refuge during the summer and winter months.  Rain floods these burrows and forces their occupants to find new hiding places.  Whether it be invertebrates, amphibians, reptiles, or even mammals, rain makes wildlife move.  As we drove along, the eyeshine of an opossum was illuminated by our headlights; the two eery points of green light faded back into the darkness as the gray, shaggy marsupial moved away.

Spring peepers and wood frogs hopped across the road every few feet.  Their high pitched whistles and guttural whines resonated from the nearby pools and streams.  Carl hadn't visited these routes for a few years (save for a brief trip we made in late autumn).  I was impressed that he retained a mental map of the area.  When I road cruise (the term herpers use for driving around and looking for amphibians and reptiles), I usually creep along at 15-20 miles per hour.  Any faster and I worry I’ll miss or hit something.  Carl, on the other hand, does something more like speed cruising.  Rocketing down the backroads, he straddles anything that could be alive, then rapidly backs up for a better look.  It’s efficient and effective, but for someone like myself who can get motion-sickness sitting in a parked car, it’s a bit of a challenge.  I tried to focus on scanning the pavement for movement as we zipped along.  It was a good distraction, but no replacement for getting out into the fresh air.  

The streamside salamander (Ambystoma barbouri)

After a few stops to inspect peepers, wood frogs, and spotted salamanders, there, stretched across the pavement—a salamander I had never seen before.  Upon closer inspection, nothing was particularly striking about this unassuming salamander.  Its body was chunky, though smaller proportioned than a spotted or a jefferson.  It displayed no bright colors or distinct markings; two shades of light gray frosted its back and sides.  The head was held high, peering up at us—an unusual behavior for this stubborn species.  Its head was also disproportionately small and snub-nosed, at least for a member of the “logger-headed” mole salamanders.  A thin, yellow line stretched across its rounded face—giving the salamander a content smile.  

“That’s our barbouri,” Carl commented as he looked down at our find.  Ambystoma barbouri, the streamside salamander.  Streamsides are unique among mole salamanders—not for their appearance, but for their behavior.  They don't breed in the temporary vernal pools that other members of this group migrate to every spring or fall.  Instead, their courtship and egg laying takes place in shallow headwater streams.  They attach their eggs to the underside of flat stones, and after hatching, the larvae grow and develop in these streams.  A. Bourbori occupy a limited range in southwestern Ohio and other nearby states where they inhabit upland forested hillsides during the summer.  

Travel just a few counties north of the streamside’s range, and you might encounter a salamander that looks nearly identical.  Until as recently as 1989, the streamside salamander was thought to be a stream-dwelling form of Ambystoma texanum, or the small-mouthed salamander.  Small-mouthed salamanders differ in appearance from the streamside in a few unremarkable ways.  They have a slightly longer snout, unique dentition with two rows of teeth, and a more wedge-shaped tail.  The most important behavioral difference is that small-moutheds breed in vernal pool habitat like the rest of the mole salamanders.  It is thought that about 4 million years ago, these two species split when A. barbouri began utilizing stream habitats.  However, breeding behavior is not a sure-fire way to tell these species apart, as both texanum and barbouri have been reported utilizing both streams and pools.

The following night, Carl and I traveled an hour north of Athens.  On a short stretch of road that cut through a patch of forest between a cornfield and tiny town, Carl spotted a single small-mouthed salamander.  Another lifer for me.  Small-moutheds inhabit lowland forests, floodplains, and fields.  If I hadn't known differently, I never would have made the distinction between this individual and the salamander from the night before. 

The small-mouthed salamander (Ambystoma Texanum)

This classic case of a cryptic species is made even more confusing by the genetic netherworld that these salamanders emerge from.  The more widespread and abundant Small-mouthed salamander (found from Ohio to Texas) is commonly parasitized by the ambystoma unisexual complex.  This group of all-female salamanders actually steals genetic information from other salamander species and incorporates it into their polyploid (more than two sets of chromosomes) genome.  This can result in animals that look quite like small-mouthed salamanders but who don't belong to the species and who might also contain the genetic information of blue-spotted salamanders and even tiger salamanders.  

In areas where A. texanum and A. barbouri overlap, some interbreeding, either historically or on going, is thought to occur.  This can blur the line between these two species and endanger the unique genetic identities of each (particularly A. barbouri due to its much smaller population).  To determine range maps where different species live, genetic testing is often helpful when dealing with cryptic species.  

When it comes to barbouri and texanum, however, genetics is another hurdle herpetologists must overcome.  The interbreeding that has taken place between these two species has left its signature in the genes of some A. texanum.  This phenomenon is called mtDNA introgression.  Mitochondrial (mt) DNA is inherited from the mother, and doesn't change much from generation to generation.  This makes it important for determining unique species lineages.  What's so difficult for this species in particular, is that entire populations of small-mouthed salamanders possess the mtDNA of streamside salamanders left over from interbreeding events.  Individuals with this condition can still be told apart by their anatomy, but this often requires collection or dissection, something most herpers aren't prepared or willing to do.  

The small-mouthed salamander we found on the second night was from a population that possess the mtDNA of the streamside salamander.  While this lends some question as to the true identity of these salamanders, the population is continuous with the known small-mouthed range.  For this reason, as well as anatomical features, we are comfortable calling them true small-moutheds.  This really shouldn't be the stopping point, however. Countless more questions need to be asked in order to expand our knowledge and better our understanding of these unique and unusual creatures. 

Even when they seem dull or indistinguishable, herps often hide some baffling secrets.  Salamanders are funny that way.  These slimy puzzles force us to think outside of what's familiar and comfortable.  I think that's why they fascinate me so much.

At the Mercy of the Rain and Weather

We crept down the dark backroad, flashlights waving over the slick pavement.  Mist pooled where the road’s winding surface bowed and dipped before arching back up like the spine of some strange sea serpent.  It was unseasonably warm for a late January night—approaching 45 degrees Fahrenheit.  The rain was a light drizzle, a fact that worried me much more than the eery isolation we found ourselves in.  It was remarkably early in the year to be looking for herps, but I couldn't pass up the opportunity.  After checking the forecast for the umpteenth time, I convinced my friend Amanda Szinte to come along on my herping escapade.  As the night wore on, we found little in the way of our amphibious quarry; perhaps it was just too early.  As we got in my car to drive the short distance back to Athens, something in my headlights caught my attention.  A Jefferson salamander (Ambystoma jeffersonianum) was wriggling off the road.

I used to think that December through February was the herping off season—at least for Ohio.  Three months to catch up on editing photos, to daydream of long past adventures, and to make plans for the next field season.  While freezing temperatures and layers of snow are sure to make the stubborn herper quite cold and disappointed, winter still offers a glimmer of potential if you know where to look. 

A young spotted salamander.

During the winter months, many dormant salamanders are poised for a burst of action.  One rainy night that peaks above 40 degrees Fahrenheit will likely convince at least a few individuals to venture above ground.  Mole salamanders (the ambystomids) are one group that can be surface active even when conditions are well below optimal.  These large, chunky salamanders spend most of their lives entrenched in mammal burrows and other subterranean hideaways.  Ambystomids are famous for their large migrations to temporary breeding pools on cold, stormy nights in late winter and early spring; the kind of nights that would make more sensible people curl up by the fireplace with a good book.  For salamanders and salamander seekers alike, these are the nights we have anticipated all year. 

It can a bit counterintuitive heading out into the dark, cold, and pouring rain, but these are the conditions salamanders require for their journey.  A good rule of thumb for most amphibians: wetter is better.  They move under the cover of night, protected from desiccation by the rain.  As ectotherms, salamanders conform to the temperature of their environment.  They require a specific range in order to become active, not too hot and not too cold (as summer heats up, salamanders become harder and harder to find).  After weeks trapped below snow and ice, a 40 degree day must feel like a trip to Daytona beach.  

A steady rain on a warm evening gets my blood pumping—tonight could be the night.  Often referred to as “the big one” by salamander seekers, just one or two nights out of the year can facilitate the movement of hundreds of amphibians.  To see one of these mass migrations requires luck and constant attention to the weather.  Misjudge the forecast and you’ll miss it.  I admit, I have never seen one of these large scale movements.  Over the years, I have enjoyed my fair share of salamander migrations and seen healthy numbers moving to and from the breeding pools.  Last year, for reasons unknown, the large migrations never came.  No one I have talked to—researchers and hobbyists alike—had the numbers that are usually expected with the rains.  Perhaps this year will be different. 

A few weeks after Amanda and I discovered that one lone Jefferson salamander, I had another good night at the same spot in early February.  I road cruised eight salamanders in total—two spotteds and six Jeffs.  I would expect these common species of Ambystomids to start migrating by the month's end, but even this is relatively early.  The warm, rainy weather seems to have affected their internal clock, making them move before it’s time.  An early spring freeze isn't normally deadly to the adult salamanders that have emerged, just a temporary setback.  Any attempted early breeding, however, could end in failure. Eggs can't handle freezing temperatures for very long.

The breeding habits of these ephemeral salamanders are fleeting.  Male Jefferson Salamanders are usually the first to arrive at the vernal pools in early to mid April.  Jeffs are lanky by mole salamander standards, with elongate bodies and long limbs.  Dark eyes bulge from their curious, rounded faces and their grayish skin is covered in light blue flecking.  By the time the Jeffs are returning to the forest, spotted salamanders (Ambystoma maculatum) have begun their immigration to the pools. Spotteds are slightly larger and more rotund.  True to their name, these salamanders are blotched with well defined yellow polkadots. Within a few weeks, both species will have returned to their underground haunts.  A handful may emerge again during fall rains, but they won't be seen in any numbers until the following spring.  

The amphibian migrations wouldn't be complete without two species of frogs.  Hundreds of spring peepers (Pseudacris crucifer) serenade the night with their deafening calls.  A chorus of their ascending peeps and wheeps can become painfully loud near breeding pools. Such a powerful voice should belong to a massive frog, but in reality, these treefrogs grow scarcely larger than a quarter.  Peepers are easily identified by the distinct X-shaped marking across their back.  Wood frogs (Lithobates sylvaticus) have a more unique call, something between a quack and a bleat.  These medium-sized frogs are the rich color of red autumn leaves.  They are some of the earliest breeding frogs in Ohio and are even capable of freezing solid in winter without any ill effects.

With this charming and boisterous cast of characters, the still woodland pools of runoff and rainwater are quickly transformed into a slurry of amorous activity.  Back country roads and empty woodlots all across Ohio briefly host this late winter spectacle.  At the mercy of the rain and weather, amphibians trek routes that generations before them have traveled.  Eyes wide, we watch from above as these single-minded creatures wriggle their way across the road and into our imaginations. For those of us that check the radar with flashlight in hand, don't forget a raincoat and a friend.  There is nothing quite like your first salamander migration.