Battling waist-high brambles strung like razor wire, Kevin P. W. Smith chases a black-and-tan dappled snake over fallen needles and leaves. When the snake slithers beneath a thick green tangle, the herpetologist hesitates. This northern pine snake, which Smith hopes to capture, is harmless. But timber rattlesnakes, like the ones Smith spotted hatching under nearby logs, are not. "This spot is perfect," Smith says, for timber newborns to be hiding. Self-preservation - rattlesnake venom, though rarely fatal, devastates the liver - overcomes scientific ambition. With a soft rustle, the pine snake melts into the detritus. Smith will have to wait another day to see if it has shed into new scales.
"Pine snakes are really cryptic," Smith says, referring to the serpents' elusive and subterranean nature. An environmental science graduate student at Drexel University, Smith has spent the past two years tracking newborn pine snakes, called neonates, in southern New Jersey. He's followed them through old cranberry bogs and blueberry fields, across a state forest and a National Guard bombing range. Smith and his colleagues want to learn where neonates hunt and hibernate to protect the dwindling pine snake population. The reptiles suffer from road kills, habitat loss and poachers, who sell the snakes as pets.
Through his research, Smith has discovered that newborn snakes have specific habitat needs, preferring to spend more time hunting in wetlands than adults. As they feed, neonates will travel less than half as far as full-grown snakes, and young snakes hibernate close to nesting sites during their first winter. So when builders claim (as one successful Walmart developer did in 2012) that relocating snakes could open up new land for construction without harming the animals, Smith is quick to call that idea "ecologically irresponsible."
Since 1979, the New Jersey Department of Environmental Protection has listed northern pine snakes as threatened, due in no small part to the loss of habitat. These snakes live in a region called the Pine Barrens, a large forest in the middle of the otherwise heavily-developed coastal New Jersey. The Pine Barrens, Smith says, is as imperiled as the rain forests.
Like the rain forests, the Pine Barrens is home to a host of rare plants and animals, from the Arogos skipper, an endangered butterfly, to the pine barrens gentian, a brightly colored flower. A defining characteristic of the forest is its sandy soil, as acidic as tomato juice, which keeps the growth of invasive plants at bay. In turn, the animals here have adapted to life among the hardy pitch pines and cedar groves. Pine snakes, for example, have wedged-shaped scales on the tips of their snouts, which the snakes use to scoop tunnels through the sand.
Six feet long when fully grown, pine snakes are one of the largest predators in the Pine Barrens. "They're large-bodied, very charismatic and beautiful," Smith says. The black dapples on a pine snake's back help it disappear into the shadows of the trees, and its white belly blends in with the sand. Pine snakes are constrictors, suffocating prey and consuming the dead animals whole. By eating insects and small mammals, Smith says, the snakes act as part of the forest's pest control. Because voles and mice are hosts for ticks, pine snakes may also help decrease the incidence of Lyme disease.
For such voracious predators, the snakes are surprisingly calm around humans. When Smith catches a baby pine snake, a few weeks old and already almost a foot long, it doesn't puff up or hiss in alarm. Instead, it weaves through Smith's fingers and smells his shirt with flicks of a forked black tongue. Its skin is dry and pleasantly smooth, and the reptile has a heft like molded rubber.
Their impressive size and docility make pine snakes popular pets. "They've got a pretty strong following among snake collectors," says Thomas Davis, a reptile breeder in Texas. According to Davis, a pine snake can fetch between $75 and $150, depending on the demand. But this popularity comes at an even greater price: poaching. Pine snakes are legal to own, provided they aren't taken from the wild, but not all collectors heed this law. A 2011 review of pine snake conservation in New Jersey reported that poachers destroy up to 40% of nests. (Davis was quick to point out that he can trace the ancestry of his northern pine snakes back to the 1970s, when the species was not protected.)
Though the snakes may be admired in captivity, their wild habits and habitats are, by and large, mysteries. And, as time goes by, it may become more difficult to find pine snakes to study. In 1986, there were about 16,400 pine snakes in New Jersey, estimates Smith's Drexel University colleagues. By 2007, that number had decreased by more than a thousand, an average loss of about 61 snakes per year.
Determining an accurate population size of wild animals is challenging, particularly for species that spend as much time underground as pine snakes. "The problem with studying a species like this," says J. Whitfield Gibbons, an ecology professor and reptile expert at the University of Georgia, "is they don't often congregate and they're not always easy to find." An amateur snake enthusiast - or herper, in Smith's parlance - can spend more than a year without spotting a pine snake. A lucky herper, Smith says, might come across a single specimen.
Smith, on the other hand, doesn't need luck. He's observed more than 40 snakes in the last season alone. But he has an advantage that most herpers don't - technology. With the help of snake surgeon Dane Ward, another Drexel University grad student, Smith implants miniscule radio transmitters in the body cavities of newborn snakes. Each transmitter emits a signal that will lead Smith to the exact location of the snake, a technique known as radio telemetry.
To follow the signal, Smith relies on a handheld radio plugged into a large metal antenna, which looks like it would be at home on a rooftop in the 1970s, tuned into The Brady Brunch. When Smith turns on the radio, the Cranberries crackle through, singing throatily about zombies. He switches the frequency and there's static, punctuated every few seconds by a faint blip. If Smith points the antenna in the right direction, the chirp gets louder. He will follow these blips, using the antenna like a divining rod, until he locates the snakes.
Over the course of the day, Smith finds five neonates above ground. He manages to catch four, to feel for the bulge of a recent meal (bones for vertebrates, smaller lumps for insects) and to make sure the surgical incisions are healing properly. The other neonates remain hidden in holes and burrows. Now is about the right time, Smith says, for shedding, which often takes place underground.
Wherever he locates a snake, Smith marks the spot on a map on his phone. After the hatching season in September and October, pine snakes don't stray far from the nest. At the 2013 conference of the Ecological Society of America, Smith reported that the snakes stayed in an area less than three football fields in size from where they were born until their first hibernation. "We can go back to see if they're using an area preferentially," says Smith, and that location, subsequently, can be protected.
"This is very valuable information about what pine snakes do in New Jersey," says the University of Georgia's Gibbons,"and replicating these field experiments in other regions would greatly help our understanding of pine snake ecology."
Telemetry also helps Smith confirm which Barrens inhabitants are consuming pine snake babies. Last year, Smith followed a trail of blips to a rotting log. He turned it over, only to be greeted by the glare of a well-fed black racer, another native snake. Smith followed the racer for three days, until it regurgitated the pine snake neonate and transmitter. "That was my white whale," he says.
One of the biggest killers of these snakes isn't a predator, however, but a human with a car. "You wouldn't believe how many snakes I see killed on the road," Gibbons says. Not only do roads bisect pine snake habitat, but the reptiles move much slower on pavement than soil. Ward, the snake surgeon, also studies how pine snakes traverse different surfaces. He found that, compared to sand, snakes take twice as long to cross concrete, and about 25 percent longer to slither along asphalt. For paved roads in New Jersey, Ward calculates that a snake must take at least two minutes to cross.
After six hours in the field, Smith starts the drive back to Philadelphia. Only ten minutes out of the forest, he spies another snake and swings the bright yellow Subaru around, pulling the car over to the shoulder. There, in the middle of the roadway, is a timber rattlesnake neonate. Smith hops out of the car. It's DOR, he says, meaning "dead on road." Cars blast by, and a passing SUV grinds the dead snake further into the asphalt. "Jesus," Smith says, "that sucks." He darts over to the carcass and pries it off of the pavement with a hooked metal pole. A string of red snake flesh hangs from its skull. Smith unfolds his pocket knife, carefully slices off the thread of tissue, and tucks the bit of meat into a plastic vial. He'll give the sample to Ward for genetic testing, and will also report the dead snake to the New Jersey DEP. Leaving the carcass amid the grass and gravel on the roadside, he gets back in the car and drives home.
[Image credit: Kevin P. W. Smith]