Early Spring Egg Masses

Before the trees have leafed out and obscured the brown tangles of understory, the early months of spring reveal hidden features across the forest's barren landscape.  White and pink wildflowers start to poke up through the leaf litter, attracting the season's first insects.  The stillness in the air makes the absence of migratory birds conspicuous, as the quiet forest awaits their jubilant calls.  Large mammals, like deer and coyotes, tread the same well-worn paths winding in thin lines up and down the wooded slopes. They have managed to eke out a living on this sparse landscape for months.

It is easier to navigate the rolling hills and ravines this time of year.  Little things, left behind by the fall and winter, now stand out.  White, sun-bleached bones—the vertebrae of a deer or the empty shell of a box turtle—linger eerily in the leaf litter.  The signs of other humans—an old beer bottle or an abandoned glove—reveal that you are not the first to venture this way.

These transitional months also reveal larger structures: the rusted out hood of a truck, or the crumbling outline of bricks where a cabin once stood.  As Carl and I hiked, the huge maw of a long abandoned train tunnel loomed into view.  Decommissioned over a century ago in 1916, the route of the old Cincinnati, Hamilton & Dayton Railroad still snakes through the forested ravine bottoms.  The tunnel is lodged out of view of most hikers, sitting in a state of decay among the hillsides.  I was amazed to see this forgotten chunk of Ohio's history, still standing as a token to the past.

A Jefferson salamander egg mass.

The early March morning was between 39 and 40 degrees Fahrenheit—right on the cusp of frog calling weather.  The brisk air felt full of potential.  With a little luck on our side, I imagined we could find anything.  Spotting the year’s first surface active garter snake or the first batch of salamander eggs feels like stumbling upon a secret.  For that moment, just you and the frogs know that life is beginning to stir.  Herps are true harbingers of spring. Following the subtly rising temperatures, salamanders start moving, frogs start calling, and egg masses start popping up everywhere.  

Carl had picked out a series of small pools on his topographic map for us to survey.  This spring was turning out to be rather fickle.  Temperatures had briefly risen into the mid-seventies only to plummet back into snow and ice days later.  We weren't sure what would be active, if anything.

The first small pond we arrived at was nothing special.  Around 15 feet across and almost perfectly round, it was clearly an old man-made farm pond that had been reclaimed by the forest.  The sparse shoots of reeds and gasses that grew around its edges were still brown and bent.  Spring warmth felt a long way off.  

As I stood on the bank, I noticed dozens of speckled, floating blobs attached to the woody reeds.  Most of these blobs were about the size of my fist, but a few were even larger.  They sat singly or in aggregations, revealing that just nights before, countless mole salamanders had migrated here to breed.  I scanned the shallows in case any adult salamanders had been left behind, but the cloudiness of the water obscured everything below a few inches.  By now, most breeding adults would have already returned to the woodlands or buried themselves in the muddy banks.    

A large group of spotted salamander eggs. Note the white egg mass in the center.  Front left there is also a wood frog mass.

Carl leaned forward with his dip net and gently scooped up two of the gelatinous balls.  One was an opaque, milky white, like the glassy eyes of a dead frog.  The other was so clear I could see each of the tiny embryos developing within.  Carefully, so as not to drop the precious cargo, Carl placed the clearer of the two in my cupped hands.  

The egg mass didn't feel like anything I had ever held before.  There was nothing slimy or unsettling about it.  Instead of oozing through my fingers, it firmly retained its shape—splitting along seams between eggs rather than melting together.  Its weightiness reminded me of a water balloon threatening to slip out of my grasp with the slightest movement.  The circular embryos were evenly spaced, each with a little, glowing halo of protective jelly.  As sunlight defracted through its multiple layers, the egg mass seemed to radiate its own light and warmth.  It was really a beautiful object. 

A spotted salamander egg mass.

Composed of around 50-150 eggs, these large masses would develop into larval spotted salamanders (Ambystoma maculatum) in 4-7 weeks.  Why some spotted salamander eggs are opaque while others are clear isn’t fully understood.  This variation is determined by the presence or absence of a glycoprotein found in the outer jelly layer.  In Ohio, there doesn't seem to be any fitness advantage for clear versus opaque eggs.  Some research, however, suggests clear egg masses may contain fewer eggs with a higher hatching success rate.

Red-spotted newts feasting on developing spotted salamander larvae.

As we moved down the pond, Carl came across a cluster of eggs that had turned yellow with a type of symbiotic algae.  This algae helps speed up the embryo’s rate of development, improving the larvae’s chances of survival.  The protective jelly that surrounds each egg was starting to break down, revealing the more developed embryos within.  Two red-spotted newts (Notophthalamus viridescence) feasted happily away on the not-yet-motile larval salamanders (a Type I Functional Response for my ecology nerds out there).  For newts and other cannibalistic amphibians, salamander eggs are an all you can eat buffet.  Requiring no time or effort to catch, the number of eggs a newt can eat is only limited by stomach size and speed of digestion.

Of the give or take 50 egg masses in the pond, most had been laid by spotted salamanders. Carl identified a few smaller masses, composed of only two dozen embryos, as the eggs of Jefferson Salamanders (Ambystoma jeffersonianum).  Despite adult Jeffs growing to similar dimensions as spotted salamanders, their egg masses are consistently smaller and hatch within a month’s time.

A raft of wood frog eggs.

While mole salamanders typically breed in fish free ponds and vernal pools, many of Ohio’s amphibians aren't picky when it comes to shallow, temporary water.  Road side ditches and tire ruts can provide breeding habitat for many salamander species and their froggy relatives.  

As we hiked back towards the vehicle, we stopped to examine a flooded patch of trail filled to the brim with egg masses.  Female wood frogs (Rana sylvatica) breed earlier than any other ranid frog in Ohio.  Eggs are laid in a communal raft that can span several meters (each female produces well over a thousand eggs).  These large aggregations can be distinguished from spotted salamander egg masses by the lack of a gelatinous sheath around the eggs.  Tadpoles become free swimming in as little as 1-2 weeks.

Three mountain chorus frog egg masses.

Having developed my search image for eggs, I realized we had overlooked a few tiny masses in the cloudy tire ruts next to the truck.  Similar in size to the egg masses of Jefferson salamanders, these eggs belonged to a specialist of tiny, shallow pools and roadside ruts: the mountain chorus frog (Pseudacris brachyphona).  These chorus frog eggs were covered in a thin layer of sediment and would take only a week to ten days to hatch. We scanned the pool, hopeful that a lingering adult might be within grasp.  These small treefrogs are a real challenge to spot, and often stop calling at the first sign of inquire. 

Carl dip netting for mountain chorus frogs.

On our way to the next pond, I thought I heard the deep, throaty croak of a mountain chorus frog coming from a series of roadside ditches.  We immediately pulled over to investigate.  While Carl sampled the water-filled ruts with his dip net, I scanned the shallow pools for eggs and amphibians.  I was met with a surprise floating just centimeters below the surface: an egg mass made up of a single strand, tightly coiled into a series of corkscrews.  I knew immediately these eggs belonged to an American toad (Anaxyrus americanus).  What was so surprising about this find was the fact that American toads don't typically start breeding until late March or early April.  These eggs were nearly a month early!  This spring was turning out to be very peculiar indeed.

American toad eggs.

The second pond we arrived at was more picturesque than the first.  Green shoots were beginning to push up through its murky water.  We found more floating spotted salamander egg masses as well as adult frogs.  Several spring peepers were beginning to call as the day warmed.  One frog made a more distinct gck-gck-gck call.  To my amusement, Carl imitated the call in hopes of locating the chorus frog, but his dip net only managed to snag a few peepers, tadpoles, and a red-spotted newt.  The mountain chorus frogs remained illusive.

We hiked along the old railway, following the calls of chorusing frogs.  Just as we reached a series of vernal pools, a large four-wheeler plowed its way through the mud and water towards us.  We watched from the sidelines, grimacing as our frogs fell silent as their habitat was torn to shreds.  Thankfully, the four-wheeler avoided the largest and most prominent of the vernal pools (sparing at least some animals, although we did find several egg masses that had been flung into the woodland).

As I got ready to dip net one of the pools, a frog leapt from the bank.  Frantically, I plunged my net under the spot where the amphibian's ripples had disappeared.  The net came up empty, but the disturbance coaxed the frog back up to the surface.  As it hung in the water, I could tell it wasn't a spring peeper.  In fact, it wasn't just one frog, but an amplexing pair of mountain chorus frogs.  I scooped the floating pair up easily.

With frogs in hand, I was able to examine my catch more closely.  I was immediately impressed by the size of these chorus frogs.  They were certainly on the larger end of the spring peeper scale, and well over twice the size of a western chorus frog.  Still only an inch or so in length, their bumpy, gray skin reminded me more of a small gray treefrog than their closer peeper relatives. Their two deep orange eyes were lightly masked and their legs and back were marked with subtle, dark striations.  Mountain chorus frogs are found only in the southern portion of the state, where they are extremely scarce during most of the year.  They emerge during the spring breeding season to call and breed, before disappearing again by early summer.

Soon, the egg masses we had discovered would start hatching, and the still pools and roadside ruts would be transformed into a bustling ecosystem of baby amphibians.  Carl and I had plans to return to some of these pools in the future to monitor their progress.  I always enjoy documenting the various life stages of Ohio's reptiles and amphibians.  Observing an organism during all parts of its life cycle is key to understanding its natural history.  There is no substitute for getting out into the woods and studying the real thing.

Until next time and keep living the field life,
Ryan B. Wagner

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.