The Ambassador of Rattlesnakes

 
We are climbing a ridge in Maryland’s Catoctin Mountains near the tightly guarded presidential retreat at Camp David. W. H. Martin walks ahead as we near the ridgetop on this Monday morning in late April. We step into a shallow depression the length of the backyard plastic sheets that, wetted with a hose, become kids’ slippery, sliding runways. Last fall’s dead, dry leaves fill this draw that now erupts in multiple thrashings of leaves by rattlesnakes’ evasion actions to our right and left and in front of Martin. Somehow, unlike in cartoons, I’m not frozen, fixed, unable to flee—but in what direction with leaf-thrashing snakes all about? I just follow Martin, hoping all the snakes have fled his path ahead of me, parting this leafy snake hazard like the Red Sea parted for Moses.

Martin is a long-time friend, herpetologist, and go-to guy for understanding Eastern timber rattlesnakes and their prospects. We often catch up with each other at our seasonal farmers market in Shepherdstown, in West Virginia’s Eastern Panhandle, or off-season at the grocery store. I admire his slim, wiry build, boundless bushwhacking energy, unflappability in the field, and ersatz uniform.

In my U.S. Army Vietnam-era draftee stint, I liked that we wore uniforms, mostly work “fatigues” in South Korea. No wardrobe decision needed. I have witnessed Martin at social gatherings, including his wedding, wear a sport coat and slacks. Otherwise he’s in uniform, sporting his angler’s vest and shallow-brimmed hat. For fieldwork he accessorizes with a two-water-bottle torso pack. It holds his lunch and a collapsible snake stick, for use when his larger snake hook might attract attention in public-use areas.

In the herpetology professional literature he frequents, he is W. H. or William H. Martin. I asked to go in the field with him in part to play a minor Boswell to his Dr. Johnson but also hoping for an exorcism of my fear of snakes. My phobia dates from an incident at age eight, barefoot. I stepped on two snakes on a path in Jackson Hole, Wyoming.

Even at that age I knew Jackson Hole had no venomous snakes. “Hole” means mountain-encircled valley. The mountain barriers rise 7,000 feet above the 6,000-foot-elevation valley floor. Winter is too cold. It lasts too long. But what is knowing when your bare foot perches on two snakes? Before I hit the ground again I am running. You’ve seen the cartoon.

Martin watched as I cleared the snake-stirred leafy draw. We looked at each other in a silence broken, so it seemed to me, by his smile: “Welcome to my world.” If this be exorcism, I’m still in Freshman 101. The snakes were merely enjoying the leaves’ insulating quality between them and the ground and their insolating quality—soaking up sunlight—above them.

We comb more ridge-side sites for snakes. Up and down, up and down. Novelist Richard Brautigan would have described me “walking as carefully as a wino” as I follow agile, energetic Martin over jumbled rock piles searching out snakes I’m ambivalent about finding. Martin has been enamored of snakes since he was a kid.

“My father introduced me to a lot of different subjects—rattlesnakes was one,” he says. “I was about one and a half years old. He took me out and taught me how to catch non-venomous snakes at two and a half. I didn’t catch rattlesnakes on my own until I was 14, because we didn’t live within walking distance of where they were.” At age 14 Martin owned a bike.

 
This Catoctin Mountains stretch lies north of the Potomac River. To our west lies the Cumberland Valley. South of the Potomac the valley formation is called the Shenandoah Valley or Great Valley. Dinosaur footprints are preserved in the Triassic lowlands in northern Virginia. Those “terrible lizards” and recent reptiles haunt our multi-layer human brain’s lower reaches. Even investors are susceptible. Witness the book title: Mean Markets & Lizard Brains: How to Profit from the New Science of Irrationality.

“People always notice a snake,” Martin declares. “You can be walking along with birds flying in and out of your line of sight, and you may not even register them. But if a snake appears in their path, people notice it.” A 2017 Harper’s Magazine “Findings” reports: “Humans are good at recognizing partially obscured snakes.” Mea culpa in that explosive leafy draw.

Farther along the ridge we come to a broad, sloping rock face crossed by a barely boot-sole-width ledge. Halfway along it, Martin finds a rattlesnake. With his snake hook, he picks it up and examines its cream-colored belly and rattle. This tells him the sex and age, and, if marked already, that they’ve met before. He measures its length against the scale on his snake hook’s handle. Satisfied, he puts the snake down with his hook, but it hangs up on a scrawny shrub. I must either follow him past this snake—its head at my right calf’s height—or retreat to a long detour below the rock face, no doubt losing face.

The snake still struggles to free itself and get to ground.

I gird up my loins and tread the ledge, passing not five inches from the rattler’s head. Martin watches stoically as this scene plays out. Joining him, I detect the faint suggestion of another smile. My vital signs had surged. Or plunged. We move on.

Martin marks snakes uniquely in black indelible ink on both sides of the rattle’s hind-most, basal segment. Lines drawn in lateral grooves on both sides of the rattle will last seven to ten years. In recaptures, unmarked segments reveal the snake’s age—how often it has molted, shed its skin, since he last marked it. Newborn snakes are not routinely marked or sexed until they’ve molted. A two-year-old will have molted four or five times, shedding its skin inside out, a half-hour process.

The snakes that startle me out of my skin are those that lie low while Martin walks by but then erupt as I approach. As I follow his lead, some snakes spook and flee. Others unnerve me, rattling—or not—in place. My imagination screens exaggerated, lurid artwork of bared-fangs rattlesnakes from the Sports Afield and Field and Stream magazines of my youth.

Estimates put U.S. venomous snakebites of humans at 7,000 to 8,000 per year. Five to ten of those bitten will die. Over a recent 24-year period in West Virginia, 36 people died from injuries by horses and cows, 26 of bee stings, five from insect and spider bites, and four from snakebites. In India, by contrast, venomous snakes, cobras and kraits mainly, may kill 30,000 people a year.

With toxins for the nervous system and blood, as well as other proteins, rattlesnake venom’s action is three-fold. It kills the prey. It starts it decomposing, being pre-digested. It also inhibits the prey’s putrefaction inside the snake, who may take days to digest it. Applied in time, anti-venom holds human death rates below 4 percent of those bitten.

Rattlesnakes may also deliver “dry bites,” venom-less warning bites. Martin thinks possibly one in five bites is a dry bite. In captivity, a rattlesnake will dry-bite a rodent if it gets too close while the snake isn’t hungry.

Martin has taken rattlesnakes, copperheads, and king snakes to school classrooms to introduce children to them and explain their habits and role in nature. A dry bite figures in one school-visit video on YouTube. A boy tells Martin about a girl he knows who got bitten but didn’t get venom. She ended up in the hospital for five days, the boy reports. Martin quizzes him, saying a dry bite shouldn’t require hospitalization. The boy insists it did. Martin presses his case. “They were trying to remove the tooth,” the boy finally says. “It broke off in her leg.”

Oh.

 
The Travels of William Bartram, first published in 1791, recounts the four-year explorations this Philadelphia-born naturalist pursued through the Carolinas, Georgia, and Florida starting in 1773. Bartram, son of naturalist John Bartram, characterized rattlesnakes as “never known to strike until he is first assaulted or fears himself in danger, and then always gives the earliest warning….” Yale University Press produced a 1958 “Naturalist Edition” of the Travels, edited by Francis Harper. It was among my father’s favorite books in his natural history collection.

Bartram’s writings fired the imaginations of British Romantic poets William Wordsworth and Samuel Taylor Coleridge. Coleridge mined Bartram’s “Alligator Hole” account of Salt Springs, Florida, for the aura of his unfinished Kubla Khan poem:

In Xanadu did Kubla Khan
A stately pleasure-dome decree:
Where Alph, the sacred river, ran
Through caverns measureless to man
    Down to a sunless sea.

The poem is one of just five or six that secure Coleridge in the English canon. Another encounter, with feisty alligators, lasting through the night—Bartram was alone in a small boat—haunted his dreams the rest of his life. An exceptional artist with a prescient ecological view of the more-than-human world, Bartram also greatly admired the Seminole lifestyle in their native place. His sympathy was ahead of its time, and the Seminole came to trust Bartram.

 

Working our way up the ridge at an angle, we come upon a small grotto-like rock outcropping. It could be a hobbit shrine. A small stream should issue from its base, where altar-like rocks go vertical in dry waterfall mode as we approach up the flat area into which that stream should flow. Martin spots a rattlesnake—he is about to step on it. We had walked up here from a different approach and seen no snakes. Now, descending a few feet off to the side, we walk up alongside them. Two lie out not so near rocks we had been scrutinizing. The duo retreats out of our sight. We stop to look into where they retreated and notice behind us another rattlesnake we just walked past.

Eventually Martin stands on a flat, rectangular rock not much bigger than baseball’s home plate. I’m right behind him on the grotto floor. We hear rattling but can neither see the snake nor place its whirring rattle. At length, I say, “It sounds like it’s under the rock you’re standing on.”

It is. Attuned to our surrounds now, we count 13 snakes in the ten-square-foot area around and beneath this flat rock, which, it turns out, is raised, resting on smaller rocks. No wonder we find no hobbits. No doubt this is the epicenter of emergence from these snakes’ overwintering den. Martin steps off the flat rock onto dry leaves that erupt with a lone snake hidden there since we began our inventory. I covet Martin’s unperturbed demeanor amidst startling flurries of rattler action. Bedraggled by day’s end, I no doubt will look like I’ve been through a wood chipper. Martin will look as he does right now, crisply dressed for the field and chipper.

We humans expend, Robinson Jeffers wrote, too much emotion on ourselves. “We should observe ourselves objectively as part of the great music,” he advises. In this music rattlesnakes play percussion with warp-speed castanet flourishes. Like many non-charismatic predators, they need to be better understood. Unfortunately, serpents’ bad press began in the Hebrew scriptures’ creation accounts. In the second creation tale, in Genesis 3, the “wily serpent” convinces Eve to eat and share with Adam the tabooed apple, for which the snake is punished with the loss of his or her legs: “You will crawl on your belly.”

“Male rattlesnakes are bigger in the shoulders,” Martin tells me, though neither male nor female seems to boast much shoulder. “Females have a mid-torso bulge if pregnant or, if recently post-partum, somewhat loose skin there.” Showing both those traits, I must be aging toward the female body type. With his stick, Martin has been picking up these snakes to age and sex them. The field biologist who dies with the best records wins, and Martin’s population and census records reach back to 1973.

Wall-to-wall humans and roads are what most threaten rattlesnakes and prevent their seasonal migrations from their dens. Proximity to roads decreases the population of old males. They travel farther from the den, often in search of sexual partners, and are larger road-kill targets. It doesn’t help that crossing a road puts the snake perpendicular to traffic, maximizing getting run over.

The middle portion of Martin’s multi-state study area falls within the greater Washington, D.C. area. “A glance at the map,” he says, “will show you that within the D.C. metropolitan area there are no road-free areas four miles in diameter. For that you must travel to north-central Pennsylvania. That’s why the biggest concentration of large populations of timber rattlesnakes occurs there.”

In Florida the solar warmth stored by highway asphalt seduces Florida blacksnakes like cocaine. Stretches of highway become so slicked with their tire-pulped bodies that cars can hydroplane out of control.

Automobiles are the Eastern timber rattlesnake’s chief predator. Before roads became so ubiquitous, rattlesnakes may well have traveled up to eight miles from the overwintering den. That’s down to one or two miles today. A den’s overall population can keep healthy despite the road-kill culling of old, big males. Martin sees few of them in den complexes near roads here. By this April day, some larger adults have already left the denning area for the woods, there to wait in ambush for their first meal of their new year.

Rattlesnakes eat mainly rodents, and I assumed a snake eats scores per year. Far from it, Martin says. “In our climate area a rattlesnake requires prey equivalent to about 70 percent of its own weight. A female putting on weight before breeding will take a bit more, but the following year, when gestating, she may take little or no food before giving birth in late August or early September. This leaves her and her young little time to feed before they hibernate in October. For an average adult weighing one and a half to two pounds, 70 percent of body weight translates into six four-ounce chipmunks or about 25 one-ounce mice.”

Most snakes likely eat a mix of rodent species. To calculate their impact on rodent populations requires considering how many prey are taken by a moderate-sized denning colony, perhaps 40 adults and 60 juveniles. Where denning numbers are high, rattlesnakes are significant predators of rodents—known vectors for Lyme disease.

 
Three days ago, Friday, had found us in the field an hour’s drive south of here at similar elevation but in a seemingly less populous rattlesnake cosmos. Friday’s limiting factor for snake sightings was temperature. Working our way up that northwestern Virginia ridge, we found only six snakes. Individuals peered out from narrow, low-profile crevices in the rocks.

We had to get face to face with each snake at far closer than its body length. Lying flat-out in crevices, perpendicular to our noses, they were too confined to strike. Such safe closeness marked a baby step toward exorcising my snake phobia.

Cresting that ridge on Friday, we walked along the Appalachian Trail. As we walked, Martin flailed his thermometer, measuring ambient air temperature. He hoped for 72 degrees. In April, when the snakes emerge from their winter den colonies, he follows multiple weather-reporting services as religiously as my farmer friend does during corn-shelling season. Martin flailed his thermometer, repeating his mantra: “Spring is stalled. Spring is stalled.”

Peak emergence for rattlesnakes coincides here with redbud and dogwood trees’ flowering. Spring climbs the mountains 120 feet per day on average. Azalea and redbud flowerings signal the final stage of emergence. This is not an aesthetic response on the snakes’ part. It is phenology, the study of plant and animal periodic life-cycle events. Biologists track the first blooming of plant species and the dates of bird migrations and insect hatches. In our part of Appalachia, the time rattlesnakes spend out of the den each year roughly corresponds to the length of our growing season.

Climate factors render yearly first-event dates subject to change. In the mid-1800s, Henry David Thoreau kept meticulous annual records of his first sightings of plant flowerings and animal appearances near Concord, Massachusetts. Comparing Thoreau’s records with today’s phenological data helps chart climate change in New England.

It was long thought that Pleistocene ice sheets pushed rattlesnakes south of the middle Appalachians. But evidence shows they actually persisted here in caves. Martin thinks rattlesnakes will survive warming climate, too. In higher, Western U.S. mountains, my alpine-adapted totem mammal the pika and its marmot and ptarmigan neighbors may not survive. Habitat-wise now, they are being pushed off the tops of their mountains. Given high enough temperature, insulating fat beneath a ptarmigan’s skin melts, killing the bird.

 

We pause for lunch at a bare-rock lookout on the ridge’s west side. For years Martin monitored several rattlesnake denning sites on higher mountains to the west of us across the Shenandoah Valley. He wanted to see whether or how their habits and characteristics might differ, because the snakes there live close to the environmental limits—combined elevation and latitude—of their range. Winter is colder and longer there and summer cooler and shorter. He found an all-male den site of mostly older rattlesnakes. “It’s a sort of bachelor quarters,” he says, “but don’t feel too bad for them. They breed with females denning at lower elevations.” Lesser environmental stress down slope doesn’t compound the reproductive stress female rattlesnakes undergo.

At the base of this ridge, mid-morning had been sunny and warming. Atop the ridge the day turned cloudy and cool with rain. At one point the temperature abruptly nose-dived from 68 to 58 degrees—not weather to coax out rattlesnakes. As the Appalachian Trail descended slightly along our southernmost stretch, we walked on a level run of smooth greenstone, 500,000-year-old rock. Whatever dirt once covered the path had worn off. This rainy day gave the smooth, chalky green rock a pastel cast. Rectangular fragments dotted the smooth rock’s edges like potshards. The greenstone struck me as restful, talismanic, a lower floor of deep time’s wild strata thrust skyward and stashed in the attic. Its dark, opal beauty makes an oddly soothing reminder that Earth’s crustal plates collided with cataclysmic force that folded and thrust up the crust as, among other things, refuge for rattlesnakes.

 
Martin walks softly and carries a snake stick. Since 1973, he has observed rattlesnakes at some 300 communal dens in the central Appalachians and tries to monitor about 20 dens on a yearly basis. Most of his study populations live in natural areas sought for day trips and weekend excursions by D.C. area residents. These natural areas’ promise of handy outdoor recreation helps Washington beat national, city livability averages by a heady 25 percent.

Few of these avid day-trippers and weekenders are aware of the den-colonies, which average 30 adult rattlers but can host over 100. Martin’s field studies sparked rerouting of a popular section of the Appalachian Trail to head off further snake-hiker encounters. The trail had been built through the emergence epicenter of a large denning colony. To be shown the former trail location is to believe.

One strategy for protecting rattlesnakes is simply to give them such avoidance cover whenever possible. At this latitude, that’s about 57 square miles.

 

Crotalus horridus is distinctive for the rattles at body’s end, but recent field evidence suggests rattling for humans is in decline. Martin thinks rattling is being bred out of many populations. “In wilder areas where rattlesnakes are likely to be accidentally trod upon by porcupines or bears,” he says, “they tend to rattle at the approach of a large animal. In areas that get a lot of human use but have few or no bears or porcupines, they tend to freeze when approached and, when the danger passes, to slip away.” Call that behavioral co-evolution.

Our relatively recent human family tree shares its mammalian taproot with opossums, but they arose 225 million years ago. Their long co-evolution with rattlers leaves them immune to the snake’s venom. Injecting a possum with 60 times the lethal dose for most mammals slightly alters their blood pressure for a couple of hours. Martin claims he is co-evolving with ticks, probably 5,000 have latched onto him. “I’m probably immune to Rocky Mountain spotted fever,” he tells me.

 

I first (and last) ate rattlesnake meat in 1976 just outside Shenandoah National Park, at the welcoming, rustic home of Darwin and Eileen Lambert. Darwin was the first employee of the national park, which was created from private lands—including cutover forests—in the 1930s. He knew the park’s plants and animals intimately. Our wild foods foraging group paid the Lamberts a visit. Darwin had found the road-killed rattlesnake near their house and cooked and shared it with us, celebrating the spirit of gatherers if not hunters.

Imagine a protein course consisting of hardy backbone with all white meat. We could have been spine surgeons. My faulty imagination pictured snake skeletal structure more like a trout’s, with many ribs curling off the backbone. On our plates sat clunky snake vertebrae far too like those on the chart at my doctor’s office. The meat tasted like a delicious cliché—like chicken, extreme white-meat chicken. Shredded and sweetened it might mimic crabmeat.

In the field now with Martin, I wonder: Did I help eat a snake from his study populations? He began his rattlesnake field studies in Shenandoah National Park in 1973 as a backcountry patrol ranger.

“The reason I took the job,” Martin told me, “was so I could be someplace where I could study rattlesnakes. By early 1974, I was working on a 180-day basis, a ‘seasonal appointment of fixed duration.’ About the first of April my supervisor called me in. With a long face, he said ‘I’ve got some really bad news. If we don’t cut you back to weekends, Personnel says, we won’t be able to keep you on through the fall, which is a really busy time, and we need you here.’”

“Okay,” Martin told his supervisor, “but just give me the government vehicle.”

“Well, if I do that I’m going to have to come up with a project for you.”

“How about letting me go out and look for rattlesnake dens?” Martin volunteered. No doubt he managed a “Please don’t throw me in the briar patch!” tone of voice.

“Well, let me see what I can come up with,” his supervisor offered.

The supervisor soon reported back to Martin: “I talked with my superintendent and what I’ve come up with is for you to go out and look at all the old sites of human habitation in the park.”

So Martin did—using a government vehicle. “After two months I turned in my report: ‘I saw no evidence of humans ever inhabiting this park!’ But I told my supervisor, ‘Incidentally I stumbled on about 25 rattlesnake dens when doing this work for you.’”

Eventually, to his mark-and-recapture studies in Shenandoah, he added study sites in southern Pennsylvania, western Maryland, and eastern West Virginia, largely finishing that phase of study in the 1980s. “I looked at life history characteristics, growth rates, age of maturity, reproductive traits, and distances traveled.”

Martin did not start college as a biology major. He first majored in international relations—until a friend told him he wasn’t diplomatic enough to be a diplomat. Now he’s the ambassador of rattlesnakes.

 
Eastern timber rattlesnakes are slow-growing and late-maturing. They typically first breed at age seven and females give birth at age eight. Individual females breed at three-year intervals, sometimes four years. Litters average eight young. Females in captivity, with no contact with males, have birthed young. The technical term is parthenogenesis.

“In common with most successful predators, rattlesnakes have a pretty low reproductive rate,” Martin says. “They don’t have many natural enemies, so there’s no push to produce lots of young.” Their natural enemies include coyotes, bobcats, skunks, foxes, hawks, and owls. Squirrels will instinctively kill small rattlesnakes, knowing that, grown large, the rattlesnake might later eat them. Indeed, one plump squirrel can supply the nutritional needs of a large rattlesnake for its full 5.3 months out of the den.

When rattlesnakes come up against something unusual, such as humans and automobiles, their low reproductive capacity works against them. Rattlesnakes have now died out in many areas heavily used by humans. Early settlers extirpated the snakes over much of their range. They routed rattlesnakes from 85 percent of their range in New England. This was not difficult because individual snake colonies were rather isolated.

“Most rattlesnakes travel only one to two miles from their ancestral den and then 95 percent of them return to it in the fall,” Martin explains. “If other dens are nearby, a few individuals will migrate to another den.” Like road kill-prone males’ wanderings, these migrations may help diversify their gene pool.

Martin’s study area includes the eastern edge of the unglaciated Appalachians from northwestern Virginia to southern Pennsylvania. The region’s dens are typically one to three miles from their nearest neighbor den. In New England most historical dens were six or more miles apart. Most that survived have neighboring dens within three miles now.

“When a den was wiped out there,” Martin says, “it was out of range of any other den. New England dens were more widely spaced because winters are colder and hibernation requirements more strict. The snakes have to get below the frost line. In New England that’s at least three feet deep.” In the warmer Deep South, rattlesnakes may overwinter in casual structures like a stump hole or the root hole of a fallen tree.

 

On Monday, I had returned home from the Catoctin Mountains fieldwork in early evening. I was bone weary and nearly walked-to-death. I ate a scant supper and went to bed well before dark. I quickly slipped into a half-waking, half-sleeping dream state in which I am inside a hand-dug well—an old square well that I’m familiar with. I’m near its top. Fieldstones line the well. Their irregularity creates small ledges. On most ledges sit rattlesnakes, coiled. I am neither frightened nor concerned. They are simply here. We are simply here, watching, watching. Snake phobia exorcised?