Vestiges of Home

I first became a scientist in my backyard. This path to life-long inquiry began when I was four years old, as soon as my family moved to a larger house, and one with a larger yard. This small, outdoor patch of land with a few large trees, bushes, and grass soon became my field area, laboratory, classroom, and all-purpose place for conducting experiments in nature. Even better, my proclivity for observing this world outside of myself was encouraged – or at least tolerated – by my mother and father.

At the time, I had no idea just how important of a role this backyard and parental support would play in my scientific career. Yet now I look back on it with a mix of gratitude and wistfulness, especially as both of my parents have departed this earth I have studied for most of my life.

Backyard-Home-IndianaHere’s where I first learned science by going into the field. Back in the day, people – including my parents – called it a “backyard.” (Photograph by Anthony Martin.)

Indiana was an odd place for a natural scientist to develop in the 1960s. I recall how kids in public schools there and then were encouraged to study and pursue careers in science. However, this was mostly because of the “space race,” in which the U.S. was competing against the U.S.S.R. to see who could first land on the moon. I loved space, staring at the moon, planets, and stars, and I watched Star Trek (the original series, of course), dreaming of some day traveling in space. Science fiction stories became an outlet for me as well. Weekly trips to the public library meant checking out books by Arthur C. Clarke, Ray Bradbury, and other sci-fi writers who expanded my perspectives and kick-started my imagination with worlds far different from those I could experience in the Midwest.

Yet science fiction wasn’t the only subject that put me on a first-name basis with librarians as I checked out stacks of books. There were two other topics that supplemented my learning, namely dinosaurs and insects. Although the study of dinosaurs had not yet gone through its major scientific revolution of the 1970s, these animals still loomed large in my and other children’s inner worlds. “Tyrannosaurus rex! Stegosaurus! Brontosaurus!” we kids would shout gleefully at one another, or at bemused adults. Books with artistic recreations of dinosaurs and the occasional movie starring dinosaurian protagonists – such as The Beast from 20,000 Fathoms, The Valley of Gwangi – fed our fancy, too.

Charles-Knight-PaintingPhoto of the original mural of Charles Knight’s ‘Triceratops and Tyrannosaurus‘ (1927), which is in the Field Museum of Natural History in Chicago, Illinois. While growing up, I saw this image many times in books, and it inspired both my artistic and scientific leanings. (Photograph by Anthony Martin.)

Still, no matter how hard I imagined, I could not see a tyrannosaur in my backyard, let alone watch it stalk and devour its prey. In contrast, insects and other animals with jointed legs delivered Tennyson’s “nature red in tooth and claw,” and much more. For about nine months of any given year during my childhood, starting in the spring, I could step out the back door of my house and watch ants, bees, wasps, butterflies, moths, spiders, and praying mantises. Plant-insect interactions in particular – such as pollination, herbivory, and wound responses in plants – drew me in, teaching me those ecological principles long before I ever heard the words “pollination,” “herbivory,” and “wound response.”

Roses-Pollination-Bee-HomeRoses blooming in the front yard of my Indiana home in August 2014, attracting a pollen-gathering carpenter bee (probably Xylocopa virginica). Female carpenter bees leave exquisitely crafted traces in wood, boring into them to make brooding cells, which they provision with pollen balls. The rose bush was originally planted by my father in the late 1970s. (Photograph by Anthony Martin.)

Leave-Insect-Feeding-TracesInsect damage on the leaf of an apple tree in the backyard of my Indiana home in August 2014. The leaf mine (left) was probably caused by a different insect from the one that made the incision along the leaf margin just to its right. Notice the brown discoloration in the leaf, a trace of its response to these injuries and its healing. My father planted this apple tree, but I’m not sure when: maybe also in the late 1970s. (Photograph by Anthony Martin.)

Predation fascinated me, probably because death was such an inappropriate topic for children to discuss with their parents. This wasn’t the artificial, acted-out stuff of TV and movies, but was in your face, or rather, in front of your face. With mild shame now (and apologies to my Buddhist friends), I remember going into my backyard, picking up ants, and throwing them into wolf spiders’ ground webs. It was a repeatable experiment in which I could observe spider response-times to tactile stimuli, and it was real.

My backyard is also where I learned to sit still and wait. As soon as I spotted a praying mantis, it was only a matter of time before that magnificent, big-eyed head swiveled to lock onto a target, moved delicately toward it, and sprang its barbed arms forward to snatch and hold its squirming dinner, which it devoured alive. Who the hell needed TV, with sharks, lions, and polar bears, when you had this, and for free?

Ah, there’s that word, “free.” This connects to the main reason why my science leaned more toward field observations and less to indoor labs, a legacy that stuck. You see, my family was poor. I didn’t know this until other kids at school made fun of my shoes, which had holes in their soles, or my pants, which were too outgrown or ragged, or my haircuts, which looked odd because my mother cut it, and badly, but with good intentions, because haircuts done by barbers were just too expensive. Compounding this (and not coincidentally), my mother and father never went to college, and my parents struggled to maintain their traditional roles, for which they were ill suited to succeed.

My father was a veteran of World-War II, and late in his shortened life was diagnosed with PTSD (post-traumatic stress syndrome), which in the 1970s was labeled “shell shock.” This condition meshed all too well with his alcoholism, meaning he had trouble keeping down a job for more than a few years. His last paycheck came from working as a night-shift janitor at a Columbia Records distribution center in Terre Haute. This job ended once he began suffering from a series of serious illnesses that put him in and out of hospitals for the last 15 years of his life. Only 59 years old, he died in the summer of 1985, just a few months before I left for Ph.D. study at the University of Georgia.

Dad-Then-LaterMy father at six months old (in 1927) and near the end of his life (circa 1982). His mother was still alive when the photo at the left was taken, but he never got to know her; she died when he was only two years old. During his last ten years of life, he developed a fondness for roses, cultivating them in our yard and bringing beauty to our home every year.

My parents were also Catholic, which in their time meant the only birth control they used was prayer. As a result, we had a big family, and I grew up with four brothers and one sister. But we were also reminded of unseen siblings, the ones who might have been. My mother was pregnant 13 times, with six successful births, but also six miscarriages and one stillbirth, meaning she bore more deaths than lives. Much later, I realized how this must have placed a profound emotional burden on her, even though she almost never mentioned it.

Judging from my mother’s affection for books and reading, I think she wanted to be an intellectual of sorts, perhaps even a scientist, or at least she wanted to learn and debate ideas with other people. This, however, was not possible when cleaning, cooking, shopping, paying bills, and otherwise taking care of six kids, all while constantly pregnant until she had her last child in 1962. Add to those demands a chain-smoking, alcohol-fueled, and narrow-minded husband who helped with none of those household tasks, followed by her being his in-house nurse and servant during the last 15 years of his life, and she didn’t stand a chance of reaching those ideals.

Dad-Back-From-War-with-MomHappier times for my parents, soon after my father came home after his service in the U.S. Army during World War II, where he fought in the Pacific. It would be his only trip abroad, but it scarred him for the rest of his life, which affected everyone around him. My mother never traveled outside of the U.S. and stayed in the Midwest for nearly all of her life.

Given such a family history, I experienced class differences and situations in college and graduate school that perplexed and occasionally stung. Even now, despite having taught at an elite private university for nearly 25 years, I still wrestle with imposter syndrome, and with how much my background sets me apart from others in my rarified academic world.

For instance, many of my academic colleagues are second-generation academics, or otherwise come from more socially elevated or well-to-do (or at least middle-class) families, where they never had to worry about paying the bills in time and making it through the month. Moreover, most of the students I’ve taught over the years have almost never experienced such economic anxieties, either. Behind all of the science I do and teach, and all of my achievements, I still hold onto a nagging, debilitating fear of scarcity, and a secret shame of how my family was on welfare and used food stamps to buy groceries. The taste of government cheese still lingers.

In the 1960s, education seemed like a way to escape from the cycle of poverty, and that was the message I constantly received from my mother and father. Sadly, that message sometimes translated as, “Don’t be failures like us.” Later in life, I turned that little frown upside down when I traveled, met wonderful people, and made scientific discoveries, many of which happened whenever I did field work in places far away from that backyard in Indiana.

Victoria-Coast-CretaceousIn grade school music class, I used to get in trouble for singing the chorus of Waltzing Matilda a bit too boisterously, which happened in between reading books about dinosaurs and insects. About 40 years later, I was walking along the coast of Victoria, Australia, looking for dinosaur tracks and insect trace fossils in the Cretaceous rocks there. Funny how that happens sometimes. (Photo by Ruth Schowalter.)

But here’s the thing about that whole “education helps people to escape from poverty” trope, one seemingly affirmed by my little personal story. This was much easier to do in the 1960s than today. The gap between the poor and rich in the U.S. today is the worst it’s been since the 1920s, with no sign of abating. People who wants to preach their faith-based mantra of “People just need to work harder to succeed” conveniently overlook that Horatio Alger was a second-generation Harvard man and Ayn Rand took government assistance. Also, an increased emphasis on student loans to pay for exploding tuition rates during the past 30 years has meant young, aspiring scientists may be starting their careers with crippling debt.

But here’s another thing: I was damned lucky because of my parents. Not despite them, but because of them. That’s what I say – and with considerable ferocity – every time someone tries to tell me (in a well-meaning way) how much my life reflects “the American dream.” For one thing, I grew up at a time when white boys were far more encouraged to go into science than African-American boys, or all girls. This accident of being born male, and in a family belonging to the dominant ethnic group of my culture, meant I benefited from the privilege of my gender and race, even as my socioeconomic background held me back.

Flagpole-ClimbingThat’s me, climbing a flagpole just outside my house when I was about seven years old, circa 1967. The rest of my family was standing below watching, cheering me on, and documenting the event. Little did I know at the time that other kids were told they couldn’t climb flagpoles, let alone make it to the top. Yes, that’s a metaphor. (P.S. The flagpole’s gone now.)

I also had lots of help along the way, such as financial aid and scholarships in college, and teaching assistantships in graduate school. This meant I didn’t have to take out student loans. Sure, I had less than $100 to my name the first month I began the teaching job I still hold (so far), but at least I began that job debt-free. Many of today’s aspiring scientists don’t have this luxury, and entrenched inequities related to gender and ethnicity continue to discourage careers in science for most Americans. Also, achieving a college degree today is nine times more likely if you come from an upper-income family than a poor one. It was never easy for poor people to become successful scientists, but it’s far, far tougher today. I was lucky.

Perhaps most importantly, though, I had parents who let me play outside and supported my learning science, however weird I must have seemed to them. I mean, staying out in the backyard for hours, flinging ants in spider webs, and watching praying mantises kill other insects? That was pretty strange, even in the 1960s. I even climbed trees in our backyard. I suspect that many of today’s “helicopter parents” would have forbidden a scrawny runt like me from going outside, let alone get my face close to spiders and insects, and handle unknown plants. Climbing trees probably would have involved first donning a series of ropes, carabiners, harnesses, padding, and a helmet, all while being supervised by a team of tree-climbing experts. Instead, like any arboreal primate should, I climbed those trees by myself, occasionally fell out of them, then got back up and climbed again. I was lucky.

Climbing-Pine-TreeMy favorite climbing tree in my backyard, which I started scaling when I was about six years old, so it must be more than 70 years old now. It was great fun to see how far I could get up into it and explore, and I found much peace just sitting in its crooks, watching the world below. Notice in the close-up (right) all of the scars on the trunk, marking the sites of the low-hanging branches, which fell off the tree a long time ago. (Yes, that’s another metaphor.)

My parents also regularly took me to our modest public library, where I checked out many books, which I read, and sometimes re-read. After my grade-school teachers alerted them that I was showing talent as an artist, my parents also spent some of their meager cash to buy me crayons, pencils, paper, acrylic paints, oil paints, and canvases as birthday and Christmas presents. So I drew and painted, and nature was my inspiration for such creations. I still can draw well – and sometimes teach drawing to my students – because of what my parents did for me. I was lucky.

Insects-Then-NowOne of my earliest attempts at scientific illustration (left), coupled with one of my more recent efforts (right). The one on the left – clearly intended as a multi-part figure – shows some of the insects I observed in my backyard, as well as some of the ecological interactions they had as pollinators, predators, and prey. The one on the right is from Figure 5.4a in Life Traces of the Georgia Coast (2013, Indiana University Press, p. 192), and is the subsurface form of a nest made by Florida harvester-ants (Pogonomyrmex badius); scale bar = 25 cm (10 in).

As I do field work today, I silently thank my father for taking me on hunting and fishing trips, effectively planting the seeds for my present-day comfort with forests, streams, lakes, and other outdoor environments. On those hunting trips, I learned what little my father knew then about tracking animals, a skill that I honed later in life, and now one of my passions. On fishing trips, I watched the behavior and ecology of freshwater crayfish, which abounded in the streams of southern Indiana. I had no clue that more than 40 years later I would reconnect with that childhood interest in crayfish by discovering the oldest fossil crayfish in Australia. I also did a different kind of fishing by studying and interpreting fish trace fossils, such as a trail left by a bottom-feeding fish about 50 million years ago in Wyoming. Then I combined my childhood love of insects and dinosaurs by writing and publishing a paper about Cretaceous insect cocoons near dinosaur nests in Montana. I didn’t see an ocean until I was 20 years old, but last year published a 700-page book, Life Traces of the Georgia Coast, which I also illustrated myself. None of those things would have happened without my parents’ help early in my life. I was lucky.

My father and mother did what they could with what life dealt them, and my mother in particular. She was born in northern Illinois and lived there through the Great Depression during her childhood. While there, she met her high-school sweetheart, who some day would be the father of her six children. He went off to fight in a world war, she waited for him to return, and they married soon afterwards. They headed south to Terre Haute, and lived in one house, then another. The latter was her home for 50 years.

Mom-Honeymoon-OutcropMy mother on her honeymoon at Turkey Run State Park in southern Indiana, 1947. While looking through a photo album in 2012, I was delighted to see this photo, showing her when she was fully in love with my father, but also enjoying what must have been a glorious waterfall. Best of all for me, though, it has an outcrop of Late Carboniferous (Pennsylvanian) Period deltaic sandstones in the background.

My mother outlived my father by nearly 30 years and got to see how her love of books, reading, and encouragement of my learning came back home to her. In 2001 and 2006, it was with much pride I mailed her each edition of a textbook I wrote and published (Introduction to the Study of Dinosaurs). In the preface to Life Traces of the Georgia Coast, I pointedly thanked her and my father for cultivating a childhood life filled with books, art, and the outdoors.

Mom-Then-LaterThe first and last photographs of my mother, when she was three years old (about 1929) and just last month, the latter photo taken by my brother Pat.

My mother died three weeks ago. The first stroke was toward the end of December 2013, and its treatment necessitated her going to a hospital, and then to assisted care. For the next eight months, she had a picture window that looked out onto a courtyard, where she watched the blooms, butterflies, and birds of what would be her last Indiana spring and summer. On August 26, she had a second and more deadly stroke, putting her in a coma that took away all of her speech, thoughts, and memories. After receiving emergency care in Terre Haute, she was evacuated by helicopter to an intensive-care unit in Indianapolis that same night. Six days later, she exhaled for the last time, less than a week shy of her 88th birthday.

Decatur-Book-Festival-Dedication-MomMe giving a talk about my most recent book, Dinosaurs Without Bones (2014) at the Decatur Book Festival last month. At the end of my talk, I dedicated it to my mother. Almost no one in the audience knew she was in a coma at the time, and none of us knew she would die three days later. (Photo by Ruth Schowalter.)

Just before this second stroke, I flew up to Indiana to see her, and we spent some time with our extended family, but also some quiet moments talking together, just mother and son. During this visit, I told her how much I appreciated everything she had done for me. We got to say goodbye to one another. We were lucky.

Today I am a trace of my mother’s and father’s love and care, and a trace of my home and backyard in Terre Haute, Indiana. Given more luck, I’ll be around for a while longer, leaving more traces of my own, and in many more places. Thank you, Dad. Thank you, Mom. You did good.

Mom-Me-Then-LaterFirst and last photos of my mother with me, separated by more than 50 years. As you can see from both pictures, my disposition hasn’t changed much. And thanks to Mom, it probably won’t.

Tracking Tybee Island

Plan to be surprised. That’s my adopted attitude whenever I’m on a developed barrier island of the southeastern U.S. coast and looking for animal traces. When primed by such open-mindedness, I’ve found that looking beyond the expected – or listening for the whispers below the shouts – can sometimes yield traces of the unexpected.

South-Tybee-Dunes-2A beach-to-dune-to-fencing-to-vacation-home transect on the south end of Tybee Island, Georgia. Not much for an ichnologist or any other naturalists to learn here, right? Try, try again. (Photograph by Anthony Martin.)

Last month, just a couple of days after a successful book-related event in Savannah, Georgia (described here), my proximity to the Georgia coast meant I had to get to the nearest barrier island, which was Tybee Island. However, a challenge presented by Tybee – and the one that causes most coastal naturalists to run away from it screaming – is its degree of development.

Actual footage of a cephalopod ichnologist reacting to the news that a field trip would go to a developed barrier island. P.S. Octopus tentacle prints would make for the coolest trace fossils ever. (Source here.)

Accordingly, Tybee Island also has large numbers of people, especially on a pretty weekend during the summer. Granted, the development is not so awful that Tybee no longer has beaches and marshes. But it does have enough paved streets, houses, vacation rentals, hotels, restaurants, shops, and other urban amenities that you can easily forget you’re on a barrier island.

Rip-Rap-Seawall-South-TybeeAn oddly shaped beach on the south end of Tybee Island, molded by a combination of a seawall, big blocks of igneous rock, fences, boat wakes, and oh yeah, waves, tides, and sand. Better than a shopping mall, for sure, but it takes some getting used to for naturalists who do their field work in less peopled places. (Photograph by Anthony Martin.)

Tybee’s beaches are also “armored” with rip-rap and seawalls, which were placed there in a vain attempt to keep sand from moving. (On a barrier island, this is like telling blood it can only circulate to one part of a body.) Moreover, its modest coastal dunes rely on fencing as a half-buttocked substitute for healthy, well-rooted vegetation holding the sand in place. The sand in those dunes also looks displaced to anyone acquainted with Georgia-coast dunes on undeveloped islands. This is because that sand really is from somewhere else, having been trucked in from somewhere else and dumped there for beach “renourishment.” There’s also not much of a maritime forest there, or freshwater ponds. So yeah, I guess those cranky naturalists have a point.

Tybee-Seawall-Rip-Rap-South-EndAnother view of the south end, showing the sharp vertical drop between the beach and dunes because of the seawall between them. The rocks (foreground) probably didn’t help much, either. (Photograph by Anthony Martin.)

Ergo, a pessimistic expectation I had before arriving on Tybee is that it would have a barrage of human and dog tracks, a tedium only punctuated by human-generated trash, all of which would assault and otherwise insult my ichnological senses. Fair or not, this prejudice kept me away from Tybee when I was doing field research for Life Traces of the Georgia Coast, and I stayed off St. Simons Island for a while, too, before succumbing in 2009. (I’m glad my wife Ruth convinced me to visit St. Simons – and I’ve been back several times since – but the interesting ichnology of St. Simons is the topic of another post.)

But then again, there was the matter of honoring the all-American right to convenience. Tybee Island is only about a 20-minute drive from Savannah, and you could drive there thanks to a causeway that connects the island to the mainland. Plus I had been to Tybee several times with students on field trips, and knew that lots could be learned there if I put a gag on my cynicism. I even had a research question, wondering how many ghost crab burrows would be in the dunes there compared to other Georgia barrier islands.

So thanks to the Hartzell Power Couple™, who were hosting Ruth and me in Savannah for the aforementioned book event, we were in their car on a Saturday morning and soon found ourselves walking on the south end of the Tybee, checking out its dunes and beaches, and (of course) their traces.

Fortunately, my question about the ghost crab burrows was answered within a few minutes of arriving at the south-end beach. Sure enough, we spotted a few of these distinctive holes, sand piles outside of the holes, and ghost-crab tracks scribbled on the dunes. Their traces weren’t nearly as common as on other undeveloped islands, but still, there they were.

Ghost-Crab-Burrows-TybeeGhost crab burrows really do exist on developed barrier islands: whoa! Although it’s still a good question about their relative abundance on a developed Georgia barrier island versus one that’s barely altered, like nearby Wassaw Island. Sounds like some science needs to be done on that. (Photograph by Anthony Martin.)

But here’s the coolest thing we saw, ichnologically speaking. The dunes also had little holes that were about the width of a pencil, with crescent-shaped openings and fresh sand aprons just outside these holes.

Wasp-Burrow-Dunes-Tybee-1What have we here? A little hole in the dunes with some freshly dumped sand outside of it. The game’s afoot! (Photograph by Anthony Martin.)

Wasp-Burrow-TybeeA close-up look of another hole very similar to the previous one. I wonder what could have made this? Oh well, I guess we’ll never know. Unless you read more, that is. (Photograph by Anthony Martin.)

I was pretty sure what made these, but as a scientist, I needed more evidence. So after pointing out the holes to my companions (Ruth and the Hartzell Power Couple™), we stood in one place and waited a few minutes. That’s when one of the tracemakers arrived.

Wasp-Digging-Burrow-TybeeBehold, the mystery tracemaker revealed! Check out that incredible digging! She’s got legs, and knows how to use them! (Photograph by Anthony Martin.)

Hypothesis confirmed! I predicted these were wasp burrows, and after watching several flying around the dunes, landing, walking up to and entering the holes, digging energetically, and emerging (repeat cycle), this was all of the evidence I needed. The wasps were some species of Stictia (sometimes nicknamed “horse-guard wasps” because they prey on horse flies). Moreover, these were female wasps making brooding chambers, little nurseries where they were going to lovingly lay eggs on paralyzed prey as a form of parasitoid behavior. (P.S. I absolutely adore parasitoid wasps, and you should, too.)

Wasp-Burrow-Sand-Kicked-TybeeUp-close view of the same wasp burrow shown above. Oh, she’s in there, all right. See those sand grains getting kicked out of the burrow? (Photograph by Anthony Martin, taken on Tybee Island.)

In our too-brief time there on Tybee, we also saw feral cat tracks in the dunes. This is a common trace on developed islands, especially where people live year-round. Sometimes these are from pets that residents let roam free, but more likely these are made by the descendants of escaped cats that then breed in the wild.

Feral-Cat-Tracks-TybeeFeral cat cats on dune sands, probably a day old at the time the photo was taken, eroded by wind and rain (see the raindrop impressions?). How to tell cat tracks from little foo-foo dog tracks? Cats make round compression shapes, a three-lobed heel pad, and rarely show claws. (Photograph by Anthony Martin, taken on Tybee Island.)

Another possible trace from a feral cat was an opened bird egg we found on the dunes. Admittedly, I’m quite the ichnological novice when it comes to egg traces, and can’t tell for sure whether this one was from predation (by a cat or other egg predator) or from hatching. But some clues are there, such as nearly half of the eggshell fragments adhering to the inside of the shell, instead of being absent.

Opened-Egg-Trace-TybeeIs it a birth trace or a death trace? Empty bird eggshells always present such questions. (Photograph by Anthony Martin, taken on Tybee Island.)

Down on the beach, one of the most common (and hence easiest) traces to find on Tybee or any other developed island with clam or snail shells washing up on their shores are predatory drillholes made by moon snails, the lions of the tidal flat. Sometimes these shells also have smaller holes, which are made by clionid sponges. Shells can thus bear the histories of life-and-death and life-after-death.

Drillholes-Bioerosion-Shells-TybeeThese shells are looking a little bored. (Yes, that’s a pun, albeit not a very good one.) The clam shell on the left was bored by a clionid sponge, and the three shells on the right were made by moon snails, probably Neverita duplicata. (Photograph by Anthony Martin, taken on Tybee Island.)

Once we were off the beach and walking on a paved road to where the car was parked, the ichnology didn’t stop then, either. In front of the car was a tree with some beautifully expressed rows of yellow-bellied sapsucker drillholes in its trunk.

Sapsucker-Holes-Tree-TybeeWhat can I say, I’m a sucker for sapsucker holes. (Photograph by Anthony Martin, taken on Tybee Island.)

So can you still do ichnology on Tybee Island, or other developed barrier islands, for that matter? Looks like…

So next time you go on that beach vacation to Tybee, Jekyll, St. Simons, or other developed barrier islands, may you likewise be pleasantly surprised on your ichnological endeavors. Good luck!

A Tale (and Tails) of Two Islands

After visiting Cumberland Island and Jekyll Island, our Barrier Islands class had entered its third day (Monday, March 11), and was now about to embark onto our third and fourth barrier islands of the Georgia coast. These islands were a Pleistocene-Holocene pair – St. Simons and Little St. Simons, respectively – and the latter was our primary goal. After all, Little St. Simons is a privately owned and undeveloped island, one of the few that has not been logged or otherwise majorly altered by those ever-nefarious and industrious post-Enlightenment humans. St Simons, though, had its own lessons to teach us, including a realization I had that ichnological factors (bivalve feces, specifically) had played a role in deciding the fate of European power struggles on the Georgia coast during the 18th century.

Just like the previous two posts, this one will be told through photos and captions, which I hope captures much of what my students and I learned during our times on these two islands. Just watch out for those tails.

Little St. Simons is a privately owned island, but is available for day tours of groups like ours that are led by their knowledgeable and friendly naturalists. Soon after arriving by small boats on the island and being greeted by the naturalists assigned to us, Laura (pictured) and Ben (you’ll see him soon enough). While there, Laura provided a brief introduction to the geological history of Little St. Simons: Holocene (probably only a few thousands years old), and rapidly gaining weight (sediment, that is) each year, supplied by the nearby Altamaha River.

Check out our air-conditioned field vehicles! Seeing that this is a field course, traveling this way was ideal for experiencing the island a bit more directly, yet without descending in a Heart-of-Darkeness or Lord-of-the-Flies sort of mode. Because that would be bad.

Little St. Simons has a healthy number of freshwater wetlands for such a small island (like this one), more closely resembling what used to be on the Georgia barrier islands before a few people decided that plantations and paper mills were great ideas.

Say, isn’t that an all-American bird? Yes, it is, but more importantly, it has a rather prominent trace next to it – a bald eagle nest – that is also occupied by a couple of young eagles. (Here, one is sticking its head out of the nest while being overseen by a protective parent.) Bald eagle nests are among the largest tree nests made by any modern bird, leading me to wonder what tree-dwelling dinosaur nests from the Cretaceous Period must have looked like.

Sorry folks, can’t get enough of bird traces on this island. Many of the tree trunks on Little St. Simons bear the horizontally aligned holes of yellow-bellied sapsuckers. These woodpeckers pierce tree trunks to cause the tree to bleed sap, which attracts insects, which get stuck, which get eaten by the sapsuckers. Sap + insects = tasty treat!

Armadillo tracks on a coastal dune at the north end of the island show just how far-ranging these mammals can get. Having only recently arrived to the Georgia coast since the 1970s, these prolific tracemakers are now on every island.

Near the armadillo tracks, also in the coastal dunes, were these mystery burrows. I had no idea what made these, as they were too small to be mole burrows, too big to be insect burrows, and too horizontal to be mouse burrows. Just a reminder that even the author of a 700-page book about Georgia-coast traces still has a lot more to learn.

Aw, look at this cute little baby alligator, which was near its momma in one of the freshwater ponds on Little St. Simons. I wonder where it came from originally?

Why, there’s where it came from: it’s momma’s nest! The arrow is pointing toward a now mostly collapsed alligator nest, which hatched the little tykes that are now in the nearby wetland. Alligator nests are composed mostly of loose vegetation that the mother collects and piles, enough that it will give off heat to incubate her eggs. Such nests have very poor preservation potential in the fossil record, but it is still very interesting to study how they disintegrate so rapidly.

Alligators (left) and birds (right, with one on her nest) last shared a common ancestor early in the Mesozoic Era, but here they are, working together to their mutual benefit. Great egrets and woodstorks nest on islands, which are guarded by large alligators, who are good deterrents to egg predators. (In a grudge match between an alligator and raccoon, who do you think would win?) As payment for this protection, alligators get an occasional chick falling out of the nest, a small evolutionary price for the birds to pay when compared to an entire clutch of eggs getting munched.

My, what a noisy tail you have! We were delighted to encounter this diamondback rattlesnake on one of the sandy roads of Little St. Simons, which urged us to approach it carefully, using a clearly audible warning and threat postures. (P.S. It worked.)

Our other guide, Ben, had an obviously deep affection for venomous reptiles, expressed first through some impromptu snake-handling. (No, he did not use his hands, nor did he speak in tongues. See that snake-handling device in his right hand?) Following our not-too-close encounter, he expounded on the ecological importance of rattlesnakes to the island, and related some interesting facts about rattlesnake behavior. Gee, you think the students might remember some of this lesson? (Personal note: Bring rattlesnakes into the classroom more often.)

At the south end of Little St. Simons is a very nice beach, and on that beach were – you guessed it – shorebird tracks. Here are some plover tracks, which could be from Wilson’s plovers, semi-palmated plovers, or some other species.

Sadly enough, our tour of Little St. Simons lasted only until 3:00 p.m., so we had some time on St. Simons to do a bit more learning. So I decided we would stop at Fort Frederica National Monument, on the north end of St. Simons Island. It turned out this was a educationally sound decision, especially when one of the rangers on duty – Mr. Ted Johnson (right) – volunteered to give our group a spirited and informative lecture about the former military importance of Fort Frederica. However, judging from the downcast looks on several of the students, I imagine they were already missing alligators, snakes, and shorebirds of Little St. Simons Island, and (of course) their traces.

The most obvious human traces at Fort Frederica are these “footprints” (foundations) of some of the buildings there in the 18th century. Established as a British outpost in Georgia to compete with the Spanish presence to the south, Fort Frederica was a thriving town as long as the military was there.

OK, you’ve no doubt read this far to find out how bivalve feces helped the English to defeat the Spanish in the mid-18th century and consequently gain a permanent foothold in Georgia (until those pesky colonials defeated them later that century, that is). See where the fort is located? Right on a point, facing a tidal channel, and with salt marsh on either side of it. Because the salt marshes are largely composed of feces and similar muddy ejecta of ribbed mussels and other invertebrates, these make for wonderfully gooey substrates. Such substrates tend to discourage rapid movement of ordinance-laden ground troops, which forced the Spanish to try other means for attacking the fort, which failed. Bivalve feces for the win! Traces rule! ¡En la cara, los conquistadores!

As our day neared an end, my students decided that an appropriate way to signal their pleasure with all they had learned was for them to give me the now-official fiddler crab salute, waving their mock claws in unison. We all plan to still use this when greeting on the Emory campus, which should thoroughly mystify other students, faculty, and especially administrators, the latter of whom will wonder if it is some sort of secret-society sign. (Which, in a sense, it will be. Be afraid. Be very afraid)

What island was next on our journey? My old favorite, Sapelo Island, just to the north of Little St. Simons and St. Simons, and as different from these as the preceding islands were from one another. Stay tuned for those photos and comments in just a few days, and get ready to learn.

Doing Field Work on a Developed Barrier Island

The second day of our Barrier Islands class field trip (Sunday, March 10), which is taking place along the Georgia coast all through this week, involved moving one island north of Cumberland (mentioned in this previous post), to Jekyll Island. I’ve been to Jekyll many times, but none of my students had, so they didn’t quite know what to expect other than what I had told them.

For one, I warned the students that Jekyll was not at all like Cumberland, which is under the authority of the U.S. National Park Service as a National Seashore. Consequently, it has a few residents, but is limited to less than 300 visitors a day. In contrast, many more people visit or live on Jekyll, and people have modified it considerably more. For example, Jekyll has a new convention center, regularly sized and miniature golf courses, a water park, restaurants, bars, and other such items absent during most of its Pleistocene-Holocene history. Another difference is that a ferry was need to get onto Cumberland, whereas we could drive onto Jekyll and stay overnight there in a hotel.

So why go there at all with a class that is supposed to emphasize the geology, ecology, and natural history of the Georgia barrier islands? The main reason for why I chose Jekyll as a destination for these students was so they could see for themselves the balance (or imbalance) between preserving natural areas and human development of barrier islands. Jekyll is one of those islands that is “in between,” where much of its land and coastal areas have been modified by people, but patches of it retain potentially valuable natural-history lessons for my students.

So what you’ll see in the following photos will focus on those more natural parts of Jekyll island, with some of the wonders they hold. However, this series of photos will end with one that will shock and horrify all. Actually, you’ll probably just shake your head and sigh with rueful resignation at the occasional folly of mankind, especially when it comes to managing developed barrier islands.

We started our morning like every day should start, with ichnology. Here, tracks of a gray fox, showing direct register (rear foot stepping almost exactly into the front-foot impression) cut between coastal dunes on the south end of Jekyll Island. The presence of gray foxes on Jekyll has caused some curiosity and concern among residents, with the latter emotion evoked because these canids are potential predators of ground-nesting birds, like the Wilson’s plover. Also, people have no idea how many foxes are on the island. If only we had some cost-effective method for detecting their presence, estimating their numbers, and interpreting their behavior. You know, like tracking.

My students show keen interest in the gray fox tracks, especially after I tell them to show keen interest as I take a photo of them. Funny how that works sometimes.

A Wilson’s plover! At least, I think it is.( Birders of the world, please correct me if this is wrong. And I know you will.) We spotted a pair of these birds traveling together on the south end of the island, causing much excitement among the photographers in our group blessed with adequate zoom capabilities on their cameras. Wilson’s plovers are ground-nesting birds, and with both gray foxes and feral cats on the island, their chicks are at risk from these predators. Again, if only we had some cost-effective method for discerning plover-cat-fox interactions. Tracking, maybe?

Here’s a little secret for shorebird lovers visiting Jekyll Island. Walk around the southwest corner of the island, and you are almost assured of seeing some cool-looking shorebirds along the, well, shore, such as these American oystercatchers, looking coy while synchronizing their head turns. These three were part of a flock of about twenty oystercatchers all traveling together, which I had never seen before on any of the islands. If you go walking on Jekyll, and know where to walk, you’ll see some amazing sights like this.

You were probably all wondering what American oystercatcher tracks look like, especially those made by ones that are just standing still. Guess this is your lucky day. Also notice the right foot was draped over the left one, causing an incomplete toe impression on the right-foot one. Wouldn’t it be nice to find a trace fossil just like this?

Black skimmers! We didn’t get to see them skim, but we still marveled at this flock of gorgeous shorebirds. These were in front of the oystercatchers, with an occasional royal tern slipping into the party, uninvited but seemingly tolerated.

Yeah, I know, you also wanted to know what black skimmer tracks look like. So here they are. Now you don’t need to use a bird book to identify this species: just look at their tracks instead!

You think you’re bored? Try being driftwood, with marine clams out there adapted for drilling into your dead, woody tissue. This beach example prompted a nice little lesson in how this ecological niche for clams has been around since at least the Jurassic Period, which we know thanks to ichnology. You’re welcome (again).

Beach erosion at the southernmost end of Jekyll gave us an opportunity to see the root systems of the main tree species there, such as this salt cedar (actually, it’s a juniper, not a cedar, but that’s why scientists use those fancy Latinized names, such as Juniperus virginiana). My students are also happily learning to become the scale in my photos, although I suspect they will soon tire of this.

Look at this beautiful maritime forest! This is what I’m talking about when I say “…patches of it [Jekyll Island] retain potentially valuable lessons in natural history.” This is on the south end of the island, and this view is made possible by walking just a few minutes on a trail into the interior.

Few modern predators, invertebrate or vertebrate, provoke as much pure unadulterated giddiness in me as mantis shrimp. So imagine how I felt when, through sheer coincidence, a couple walked into the 4-H Tidelands Nature Center on Jekyll, while I was there with my class, and asked if I identify this animal they found on a local beach. The following are direct quotations from me: “Wow – that’s a mantis shrimp!! Squilla empusa!! It’s incredible!!” I had never seen a live one on the Georgia coast, and it was a pleasure to share my enthusiasm for this badass little critter with my students (P.S. It makes great burrows, too.)

A stop at the Georgia Sea Turtle Center on Jekyll was important for my students to learn about the role of the Georgia barrier islands as places for sea turtles to nest. But I had been there enough times that I had to find a way to get excited about being there yet again. Which is why I took a photo of their cast of the Late Cretaceous Archelon, the largest known sea turtle. I never get tired thinking about the size of the nests and crawlways this turtle must have made during the Cretaceous Period, perhaps while watched by nareby dinosaurs.

At the north end of Jekyll, shoreline erosion has caused the beach and maritime forest to meet, and the forest is losing to the beach. This has caused the forest to become what is often nicknamed a “tree boneyard,” in which trees die and either stay upright or fall in the same spot where they once practiced their photosynthetic ways.

Quantify it! Whenever we encountered dead trees with root systems exposed, I asked the students to measure the vertical distance from beach surface to the topmost horizontal roots. This gave an estimate of the minimum amount of erosion that took place along the beach.

Perhaps a more personal way to convey the amount of beach erosion that happened here was to see how it related to the students’ heights. It was a great teaching method, well worth the risk of being photobombed.

Are you ready? Here it is, in three parts, what was without a doubt the traces of the day. Start from the lower left with that collapsed burrow, follow the tracks from left to right, and look at that raised area on the right.

A close-up of the raised area shows a chevron-like pattern, implying that this was an animal that had legs, and knew how to use them. Wait, is that a small part of its tail sticking out of the left side?

Violá! It was a ghost shrimp! I almost never see these magnificent burrowers alive and outside of their burrows, and just the day before on Cumberland Island, the students had just learned about their prodigious burrowing abilities (the ghost shrimp, that is, not the students). I had also never before seen a ghost shrimp trackway, let alone one connected to a shallow tunnel on a beach. An epic win for ichnology!

This may look like soft-serve ice cream, but I suspect that it’s not nearly as tasty. It’s the fecal casting of an acorn worm (Balanoglossus sp.), and is composed mostly of quartz sand, but still. These piles were common on the same beach at the north end of Jekyll, but apparently absent from the south-end beach. Why? I’m guessing there was more food (organics) provided by a nearby tidal creek at the north end. But I’d appreciate all of those experts on acorn worms out there to augment or modify that hypothesis.

This is how dunes normally form on Georgia barrier-island beaches: start with a rackline of dead smooth cordgrass (Spartina alterniflora), then windblown sand begins to accumulate in, on, and around these. Throw in a few windblown seeds of sea oats and a few other dune-loving species of plants, and next thing you know, you got dunes. Dude.

In contrast, here is how not to form dunes on Georgia barrier-islands beaches. Build a concrete seawall on the middle part of the island, truck in thousands of tons of metamorphic rock from the Piedmont province of Georgia, place the rocks in front of the seawall, and watch the beach shrink. So sad to see all of that dune-building smooth cordgrass going to waste. Anyway, the contrast and comparison you just saw is also what my students experienced by standing in both places the same day.

Jekyll Island gave us many lessons, but we only had a day there. Which islands were next? St. Simons and Little St. Simons, with emphasis on the latter. So look for those photos in a couple of days, in between new exploits and learning opportunities.





Cumberland Island, Georgia: Not a Barrier to Education

When learning about the natural sciences, there comes a time when just reading and talking about your topics in the confines of a classroom just doesn’t cut it. This semester, we had reached that point in a class I’m teaching at Emory University (Barrier Islands), in which we all needed a serious reality check to boost our learning. So how about a week-long field trip, and to some of the most scientifically famous of all barrier islands, which are on the coast of Georgia?

Last Friday, March 8, our excursion officially began with a long drive from the Emory campus in Atlanta, Georgia to St. Marys, Georgia. Fortunately, Saturday morning was much easier, only requiring that we walk across the street, step onto a ferry, and ride for 45 minutes to Cumberland Island. Cumberland was our first island of the trip, and the southernmost of the Georgia barrier islands. I have written about other topics there, including the feral horses that leave their mark on island ecosystems, the tracks of wild turkeys, and those marvelous little bivalves, coquina clams.

So rather than my usual loquacious ramblings, punctuated by whimsical asides, this blog post and others later this week will be more photo-centered and accompanied by mercifully brief captions. This approach is not only a practical necessity for proper time management while teaching full-time through the week, but also is meant to give a sense of the daily discoveries that can happen through place-based learning on the Georgia coast. I hope you learn with us, however vicariously.

After a 45-minute ferry ride to Cumberland Island, the students received a different sort of lecture when naturalist extraordinaire Carol Ruckdeschel – who is writing a book about the natural history of Cumberland Island – met with them and gave them a brilliant overview of the island ecology. She mostly talked with the students about the effects of feral animals on the island, then spent another hour with us in the maritime forest and through the back-dune meadows. It was a real treat for the students and me, and a great way to start the field trip.

A leaf-cutter bee trace! Despite my writing about these and illustrating them in my book, these distinctive incisions were the first I can recall seeing on the Georgia barrier islands. These traces were abundantly represented in the leaves of a red bay tree we spotted along a trail through the maritime forest, making for a great impromptu natural history lesson for the students.

A freshly erupted ghost shrimp burrow on the beach at Cumberland, in which the students were lucky enough to witness the forceful ejection of muddy fecal pellets by the shrimp from the top of its burrow. I mean, really: explain to me how the life of an ichnologist-educator can get any better than that?

The fine tradition a field lunch, made even more fine by the addition of fine quart sand to our meals, freely delivered by a brisk sea breeze. Did the sand leave any microwear marks on our teeth? I certainly hope so.

A student is delighted to test my ichnologically based method for finding buried whelks underneath beach sands, and find out that it is indeed correct. (Was there any doubt?) Here she is proudly holding a live knobbed whelk, which I can assure you she promptly placed back into the water once its photo shoot was finished for the day.

Just to join in the fun, other students decided my “buried whelk prospecting” method required further testing. Let’s just say this student did not disprove the hypothesis, but rather seemed to confirm it, and doubly so. It’s almost as if ichnology is a real science! (Yes, these whelks went back into the water, too.)

OK, enough about marine predatory gastropods (for now). How about some of the largest horseshoe crabs (limulids) in the world? We found a large deposit of their carapaces above the high-tide mark, some of which were probably molts, but others recently dead. Sadly, though, we did not see any of their traces. Bodies only do so much for me.

Where do dunes come from? Well, a mother and father dune love each other very much… No wait, wrong story. What happens is that dead cordgrass from the salt marshes washes up onto the beach, where it starts slowing down wind-blown sand enough that it accumulates. Now it just needs some wind-blown seeds of sea oats and other plants to start colonizing it, and next thing you know, dune. Dude.

Ah, a geological tradition in action: comparing actual sand from a real outdoor environment to the sand categories on a handy grain-size chart, and using a hand lens. It’s enough to bring a tear to the eyes of this geo-educator. Or maybe that was just the wind-blown sand.

Finally, something that really matters, like ichnology! This is a three-for-one special, too: sanderling feces (left), tracks, and regurgitants (right), the last of these also known as cough pellets. Looks like it had coquina and dwarf surf clams for breakfast.

Wow, more shorebird traces! The tracks are from a loafing royal tern, and it clearly needed to get a load off its mind before moving on with the rest of its day.

Tired of shorebird traces? How about a modern terrestrial theropod? Wild turkey tracks in the back-dune meadows of Cumberland were a happy find, leading to my grilling the students with the seemingly simple question, “What bird made this?” They did not do well on this, but hey, it was the first day, and at least no one said “robin” or “ostrich.”

Did somebody say “doodlebug?” This long, meandering, and collapsed tunnel of an ant lion (a larval neuropteran, or lacwing) tells us that this insect was looking for prey in all the wrong places.

Behold, tracks that bespeak of great, thundering herds of sand-fiddler crabs that used to roam the sand flats above the salt marsh. Where have they gone, and will they ever come back? Who knows where the males might be waving their mighty claws? Do the female fiddler crabs suffer from big-claw envy, or are they enlightened enough to reject cheliped-based hierarchies imposed upon them by fiddler-crab society? All good questions, deserving answers, none of which make any sense.

Yes, that’s right, feral horses are really bad for salt marshes. Between overgrazing and trampling, they aren’t exactly what anyone could call “eco-friendly.” My students had heard me say this repeatedly throughout the semester, and Carol Ruckdeschel said the same thing earlier in the day. But then there’s seeing it for themselves, another type of learning altogether.

And the day ended with beautiful ripple marks, beckoning from the sandflat below the boardwalk on our trip back onto the ferry. Even this ichnologist can appreciate the aesthetic appeal of gorgeous physical sedimentary structures.

What’s the next island? Jekyll, which is just north of Cumberland along the Georgia coast, visited yesterday. Stay tuned, and look for those photos soon.

Marine Moles and Mistakes in Science

A first day of field work in the natural sciences can be expected to hold surprises, no matter what type of science is being attempted. Sometimes these are unpleasant ones, such as finding out the fuel gauge in your field vehicle – which you are driving for the first time, and in a remote place – doesn’t work. Other times, you make a fantastic discovery, like a new species of spider, a previously undocumented invasive plant, or a fossil footprint. But sometimes you see something that just makes you scratch your head and say, “What the heck is that?”, or more profane variations on that sentiment.

What is this long, meandering ridge making its way through a beach to the high tide mark on Sapelo Island, Georgia, and what made it? If you’re curious, please read on. But if you already know what it is, then you know a lot more than I did the first time I saw something like this. (Photograph by Anthony Martin.)

The last of those three scenarios happened to me on Sapelo Island, Georgia, in June 2004. My wife Ruth was with me, and we had just arrived on the island the previous afternoon, having stayed overnight at the University of Georgia (Athens) Marine Institute, or UGAMI. We decided that our first full morning in the field would be at Nannygoat Beach on the south end of Sapelo, which is a 5-minute drive or a 20-minute walk from the UGAMI.

We drove a field vehicle there (the gas gauge and everything else worked), parked, and took the boardwalk over the coastal dunes. Our elevated view from the boardwalk afforded a good look at many insect, ghost crab, bird, and mammal tracks made in the early morning. Circular holes punctured the dunes, made by ghost crabs (Ocypode quadrata). Sand aprons composed of still-moist sand were next to these burrow entrances, bearing crisply defined ghost-crab tracks, although early-morning sea breezes had already started to blur these.

At some point after walking onto the beach, though, we saw traces that we had not noticed in previous visits to Sapelo, and ones I have rarely seen there or on other Georgia barrier islands since. These oddities were meters-long, slightly sinuous to meandering ridges, about 15-20 cm (6-8 in) wide, extending in the sandy areas from the dunes through the berm and down to the high-tide mark, where they ended abruptly.

Same meandering ridge shown in the first photo, but viewed from the high-tide mark, showing how it connects with the primary dunes. Note how a few holes are punched in the part near me: more about those soon. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia. P.S.: My wife Ruth is the scale in both photos, fulfilling one of the top 10 signs that I might be a geologist.)

Although a few ridges crossed one another, they rarely branched, and if they did, the branches were quite short, only about 10-15 cm (4-6 in). When we followed them to the dunes, they seemed to originate from some unseen place below the sandy surfaces. We investigated further by cutting through some of the ridges to see what they looked like inside. They turned out to be mostly open tunnels with circular cross sections about 5 cm (2 in) wide, slightly wider than a U.S. dollar coin. They were mostly hollow, and only occasionally did we encounter a plug of sand interrupting tunnel interiors. This supposition was backed up by ridges that had collapsed into underlying voids. A few of the ridges stopped with a rounded end the same diameter as the ridge, or as a larger, raised, elliptically shaped “hill.”

Ridge with quite a bit of meander in it. Check out the short branch toward the top right, where the tracemaker must have changed its mind and backed up, then continued digging toward the viewer. Scale = 15 cm (6 in). (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

Two separate ridges intersecting, caused by one crossing the other, resulting in “false branching.” Also notice the partial collapse of sand into underlying hollow tunnels and how one of the ridges ends in a rounded mound. Scale = 15 cm (6 in). (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

A short ridge ending in a raised, elliptical “hill,” connected to a partially collapsed tunnel that is not otherwise evident as an elevated surface. Same scale as before. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

Ruth and I agreed that these tunnels were burrows, instead of some random features made by the winds, tides, or waves. But by what? Clearly their makers were impressive burrowers, capable of digging through meters of sand. Their bodies also were probably just a little narrower than the burrow interiors, which helped us to think about body sizes. Then we considered where we were – dunes and beach – and what animals were the most likely ones to burrow in these environments.

A process of elimination – determining what they were not – was a good way to start figuring out their potential makers. For example, no way these burrows were from insects, such as beetle larvae, ant lion larvae, or mole crickets, because they were just too big. Insects also have a tough time handling salinity, so once they got to the surf zone with its saturated, saline sand, they would have had problems, or (more likely) an aversive reaction and turned around immediately instead of plowing ahead.

Insect burrow in coastal dune sand, made by a small beetle. Look at both the form and scale, and you’ll see this is not a match for what we were seeing. Scale in centimeters. (Photograph by Anthony Martin, taken on Cumberland Island, Georgia.)

Small mammals, like beach mice (Peromyscus polionotus), didn’t seem like good candidates either. Beach-mouse burrows are totally different from what we were seeing, and their burrows do not run all of the way down to the intertidal zone. Mice, like insects, also don’t like marine-flavored water; even if they might be able to temporarily tolerate it, they wouldn’t continue to burrow through moist, salty sand.

A beach-mouse burrow, with their tracks coming and going. Either the mice dug this burrow, or they occupied an abandoned ghost-crab burrow. Regardless, this also doesn’t match our mystery traces. Scale in millimeters. (Photograph by Anthony Martin, taken on Little St. Simons Island, Georgia.)

This led to an initial hypothesis that these burrows were from one of the most common larger burrowing animals in the area, and one comfortable in dune, berm, and beach environments with saturated, salty sand. These could only be from ghost crabs, I thought, an explanation supported by undoubted ghost crab burrows that perfectly intersected these tunnels, accompanied by undoubted ghost-crab tracks.

Ghost-crab burrows intersecting tunnels, accompanied by lots of ghost-crab tracks. Wow, that’s really convincing circumstantial evidence, wouldn’t you say? (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

End of story, right? Well, no. I and a lot of other scientists have said this before, but it bears repeating: part of how science works is that in its practice we do not prove, we disprove. I somehow knew the “ghost crab burrowing horizontally through meters of sand from the dunes to the beach” hypothesis was a shaky one, and it bothered me that it just didn’t seem right. So I started reading as much as possible about ghost-crab burrowing behaviors. I thought I already knew a lot about this subject, but nonetheless was willing to acknowledge that there might be some holes in my learning (get it – holes?) that needed filling (get it – filling? Oh, never mind).

The gentle reader probably surmised what happened next. That’s right: not a single peer-reviewed reference mentioned ghost crabs digging meters-long shallow tunnels from the dunes to the beach. So either I was wrong, or I had documented a previously unknown and spectacular tracemaking behavior in this very well-studied species. A single cut by Occam’s Razor simply said, “You’re wrong.”

You thought I made long horizontal burrows that go all of the way from the dunes to the surf zone? Wow, you primates are dumber than I thought. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

If not a ghost crab then, what else could make meters-long horizontal burrows of the diameter we had seen? This is when I began to reconsider my original rejection of moles as possible tracemakers.

So what am I: chopped liver? (Photograph from Kenneth Catania, Vanderbilt University, and taken from here.)

Here’s what was the most interesting about this mistaken interpretation: it was made because of where we were. In other words, our initial mystification about these traces stemmed from their environmental context. Had we seen these burrows winding down a sandy road in the middle of a maritime forest on Sapelo Island, we would not have hesitated to say the word “mole.” Yet because we saw exactly the same types of burrows in coastal dunes and beaches, we said, “something else.”

A long, meandering mole burrow in the sandy road going through a maritime forest on the north end of Sapelo Island. So if you see a burrow like this in the forest, you instantly say “mole.” But if you see it on the beach, you say, “Um, uh, duh…must be something else!” My tracks (size 8 1/2, mens) and 15 cm (6 in) photo scale for, well, scale. (Photograph by Anthony Martin.)

Another long, meandering ridge ended in a rounded “hill,” a trace that no one would hesitate to call a mole burrow, especially because it’s in the middle of a maritime forest. (Photo by Anthony Martin, taken on Sapelo Island, Georgia.)

A trip back to the literature further confirmed the mole hypothesis while also serving up a big slice of humble pie. I was embarrassed to find that these same burrows were described and interpreted as mole burrows in an article published in 1986. Even more mortifying: my dissertation advisor (Robert “Bob” Frey) was the first author on the article; it had been published while I was doing my dissertation work with him; and I had read the article years ago, but didn’t remember the part about mole traces. It was like these burrows were saying to me, “Go back to school, young man.”

OK, so these are mole burrows. Case closed. Now that we’ve identified them, we can stop thinking about them, and go on to name something else. But that ain’t science either, is it? This one answer – mole burrows – actually inspires a lot of other questions about them, which could lead to heaps more science:

Which moles made these burrows? The Georgia barrier islands have two documented species of moles, the eastern mole (Scalopus aquaticus) and star-nosed mole (Condylura cristata). Of these two, eastern moles are relatively common on island interiors, whereas star-nosed moles are either rare or locally extinct from some of the islands. But star-nosed moles are also more comfortable next to water bodies and seek underwater prey. So could these traces actually signal the presence of star-nosed moles in dune and beach environments? Frey and his co-author, George Pemberton, originally interpreted these as eastern mole burrows, but they also didn’t eliminate the possibility of star-nosed moles as the tracemakers, either.

What is the evolutionary history of moles on the Georgia barrier islands? Are these moles descended from populations isolated from mainland ones 10,000 years ago by the post-Pleistocene sea-level rise, or do they represent more modern stock that somehow made its way to the islands? A genetic study would probably resolve this issue, but who the heck is going to compare the genetic relatedness of moles from the Georgia barrier islands to those on the mainland?

What were they eating? Moles don’t just burrow for the exercise, but for the food. While burrowing, they are also voraciously chowing down on any invertebrate they encounter in the subsurface. But what would they eat in beach sands? As many shorebirds know, Georgia beaches are full of yummy amphipods, which would likely more than substitute for a mole’s typical earthworm and insect-filled diet in terrestrial environments. Yet as far as I can find in the scientific literature, no one has documented mole stomach contents or scat from coastal environments to test whether these small crustaceans are their main prey or not.

What happened to these moles once their burrows got to the surf zone? Did they turn around and burrow back, or did they go for a swim in the open ocean? The latter is actually not so far fetched, as moles are excellent swimmers, especially star-nosed moles. But how often would they do this?

Just how common (or rare) are these burrows in beaches? Just because I just perceive these burrows as rare could be an example of sample bias. Yes, I wrote an entire book about Georgia-coast traces and tracemakers and have done field work on the islands since 1998. But I don’t live on the Georgia barrier islands, nor have I spent more than a week continuously on any of them. Keenly observant naturalists who live on the islands or otherwise spend much time there could better answer this question than me. I suspect they’re actually much more common than I originally supposed, and now look for them to photograph or otherwise document whenever I go back to any of the islands.

Would such burrows preserve in the geologic record? Probably so, especially if they were made in dunes and filled with a differently colored or textured sand. But I’ll bet that nearly every paleontologist or geologist would make the same mistake I did, and reach for a burrowing marginal-marine crab or some other invertebrate as the tracemaker.

Geologists would be further fooled if fossil mole tunnels were intersected by genuine ghost-crab burrows, which would constitute a great example of a composite trace made by more than one species of animal. But why did the crabs burrow into the mole tunnels? Because it was easier. After all, the moles left hollow spaces and loosened sand over wide areas, practically begging ghost crabs to exploit these disturbed areas.

Anyway, I doubt many geologists would think of a small terrestrial mammal as a tracemaker for such burrows in sedimentary rocks formed in marginal-marine environments, although I’d love to be proved wrong on this. I’m hoping my writing about it here will help to prevent such confusion, and that whoever benefits from it will buy me an adult beverage as thanks.

In summary, this example of making a crab burrow out of a mole tunnel thus serves as a cautionary tale of how where we are when making observations in the field can influence our perceptions. But it also goes to show us how our wonderment with what we observe in natural environments can be renewed and encouraged by daring to be wrong once in a while, and learning from those mistakes.

Further Reading

Frey, R.W., and Pemberton, S.G. 1986. Vertebrate lebensspuren in intertidal and supratidal environments, Holocene barrier island, Georgia. Senckenbergiana Maritima, 18: 97-121.

Gorman, M.L., and Stone, R.D. 1990. The Natural History of Moles. University of Chicago Press, Chicago, Illinois: 138 p.

Harvey, M.J. 1976. Home range, movement, and diel activity of the eastern mole, Scalopus aquaticus. American Midland Naturalist, 95: 436-445.

Henderson, R.F. 1994. Moles. Prevention and Control of Wildlife Damage, Paper 49, University of Nebraska, Lincoln: D51-58. (Entire text here.)

Hickman, G.C. 1983. Influence of the semiaquatic habit in determining burrow structure of the star-nosed mole (Condylura cristata). Canadian Journal of Zoology, 61: 1688-1692.

The Ichnology of Peeps

Once a year, around Easter time, an attentive beachcomber might notice the unusual traces of a migratory animal on the sands of the Georgia barrier islands. Based on a few clues, its traces point toward five identically sized and conjoined tracemakers, indicating some sort of obligatory group behavior.

Eyewitnesses swear these tracemakers – nicknamed “peeps” – possess a few superficial avian qualities, yet they lack many of the anatomical traits we normally associate with birds, such as, well, wings and legs. Indeed, they apparently have flat ventral surfaces, which with their forward movement along beach sands cause trails, rather than trackways.

Peep trail, observed on berm of Nannygoat Beach, Sapelo Island, Georgia. Oddly enough, this trail shows both a sudden start and end, almost as if the peeps were placed and removed from the surface, respectively.

As a result, peep trails – which are sometimes sinuous, but always harmonious – consist of five parallel grooves, each spaced equally and separated by six ridges, four on the interior of the trail and one on each side. Lateral movements along the length of a peep trail can vary the height of these ridges, depending on whether the peeps are banking to the right or left as they turn.

Although flying ability in peeps has only been inferred on the basis of their possible avian affinity, peep traces show only very brief periods of airborne activity. These traces indicate a somewhat clumsy strategy when approaching ground surfaces, culminating in abrupt vertical descents best described to laypeople as “crashing.” Ideally, all five peeps leave impressions of their cranial anatomy, which includes rudimentary beaks and foreshortened premaxillas. I have no idea if this facial configuration reflects acquired characteristics – caused by frequent crashes – or are more attributable to their original genotype.

Peep landing trace, in which impressions of the anterior anatomy are preserved. Note the short beak marks and rounded dorsal portion of the torso, but with a thin shelf close to the ventral surface. Sand ridges around the impressions suggest the tracemaker bounced after landing.

Peep resting traces are sometimes subtle, owing to their light weight, which according to some sources is about 85 grams (3.0 ounces) in total, or 17 grams per peep. In such instances where their resting traces are recognized, though, peep ventral anatomy is more clearly discernible. Interestingly, the anterior portion of their bodies is rounded and broad, but tapers into a blunt, narrow posterior with a possible upturned tail, the latter suggested by a thin groove bisecting the dorsal part of this posterior mark.

But perhaps the puzzling aspect of these traces is their lack of feather impressions. This evidence shows that peeps, despite their inferred avian affinity, must have become secondarily featherless, despite a long history of descent from non-avian dinosaurs.

Peep resting trace, barely noticeable owing to the light weight of its tracemakers, yet still apparent through its typical overall five-part form.

As is typical with resting traces, these are often connected directly to traces of other behaviors, such as locomotion or burrowing. Indeed, peep resting traces sometimes segue into or out of shallow burrows, which again have five impressions on their bases. Burrowing is presumably an adaptive strategy to avoid predation, implying delectable qualities.

A peep resting trace that is also a burrow, and connecting to an exit mark (right) in which the peep tails left impressions with movement up and out of the excavation.

Peeps are rarely sighted outside of small, cellophane-wrapped boxes in urban shopping centers. Nevertheless, one spring I was lucky enough to see a gaggle of them (five, of course), exuberantly unbound. on a beach of Sapelo Island, Georgia. Thus I was able to observe them making trails, landing traces, resting traces, and actively burrow just above the intertidal zone, which may very well be their natural habitat.

Five peeps making a trail as conjoined unit on a Sapelo Island beach, a behavior predicted by their traces. Who says ichnology isn’t a real science?

Peep landing marks from a short aerial excursion, with the peep presence a short distance away also supporting the interpretation of their bouncing forward after landing.

Peeps exiting a shallow burrow that was also a resting trace, a blend of behaviors often implied by traces.

Peeps initiating a deeper burrowing strategy, perhaps as a form of predation avoidance. Note how the trail becomes shortened, straight, and produces a large pile of sand in front of the direction of movement.

Never-before-seen evidence of how these legless peeps burrow! They use a combination of minute lateral undulations and forward movement directed downward at a shallow angle. As a result, the trail entering the burrow becomes covered by sand ridges produced by the subsequent behavior.

Success! These peeps have managed to bury themselves, leaving only a small portion of their heads exposed, with all five watching warily for predators,

Peeps have been the subject of intensive research, but much of this work, however valuable, has been laboratory based and highly experimental. Thus the data I’ve presented here on their traces should greatly expand our understanding of their behavior in the context of natural settings. Further insights on the biology of peeps are currently murky, but their traces hold promise of fitting them into a taxonomic category more precise than “looks like little chicks.”

Although trace fossils of peep trails, landing traces, resting traces, and burrows have not yet been discovered, I propose these should have the following ichnogenus and ichnospecies names: Peepichnus quinquecalles (= “Peep trace of five trails”). However, I anticipate some of my ichnological colleagues will want to split the ichnotaxonomy of peep traces on the basis of whether they were moving horizontally versus vertically (the peeps, not my colleagues) and other such nuances. Personally, I think they just need to relax, stop coming up with so many silly, unpronounceable names, and just enjoy the sweetness of these little tracemakers of the Georgia coast.