Snake lore in the Jungles of Costa Rica
The itching came in waves, tickling and irritating to the point of distress. An involuntary ripple ran through her long slender body, and she changed position, trying to get comfortable. A vibration in the earth underneath alerted her senses, something big was moving around and not far away. The vibration increased in intensity as the large animal approached and passed nearby, then subsided and finally ceased. Relieved that the danger had passed, toboba tiznada returned her attention to the persistent itching.
Again she moved her lithe body rubbing against the root of the tree where she hid. Relief would be hours in coming as the old skin worked itself loose and separated from the new. It was always the same and little could be done to speed up the process. She rested for a while and again flexed her muscles and rubbed against the hard wooden surface. The old skin slipped free on her head and then farther back on her neck. Maybe it wouldn't take so long.
After a time the vibration returned, slower this time and with less intensity. Toboba tiznada shrunk back into her hiding spot and lay still, waiting. The animal was on the same path as the one that passed earlier but coming from the opposite direction. Then it hesitated, and changed course. A wave of panic ran along her spine. It was going to cross on her side of the tree right in front of her hiding place. She moved her head slightly to get a better look, but the loose skin partially covered her eyes, limiting her vision. The animal was much too big to eat, but it might harm her. Involuntarily her muscles tensed almost to the snapping point.
The large animal moved in front of the root under which she was nestled, its shadow discernible through the dry flaky skin. Its body heat stimulated her sensors and, somewhere in her nervous system, a trigger snapped. Her head shot forward, mouth opened wide, fangs extended until her nose hit the heat source. She bit down. One fang penetrated first the coarse fabric and then deep into the flesh and injected the liquid protein. The other fang was deflected as it went through the fabric and only scratched the skin of the large intruder. Muscle contractions quickly reversed bringing her head back into the coil, then tensed again, ready for a second strike. Toboba tiznada huddled back into the hollow and waited.
Nancy Ravenfeld, known fondly as "Raven" to her friends, looked about her for the source of the sting. There were no wasps or bees buzzing around, but she could swear she had been stung. Thinking a nest must be under the massive buttress roots of the rainforest tree she turned for a better look. Underneath the root lay the source of her "sting," a mature fer-de-lance viper (Bothrops asper,) about one and a half meters in length, with its body curled into a tight coil. In her five years in Costa Rica, Raven had only seen two other fer-de-lances and neither of them was this light colored. A wave of terror hit as she realized what had happened. Raven's immediate reaction was to get away from the snake, which she did, scrambling back down the hill, until something inside her said, "Wait! I'm not supposed to run with a snake bite." She collected her wits and tried to figure out what to do.
The hike to the road through the farm would take too long. It seemed the best option was to cross the river to the palm plantation where she could hear workers' voices and trucks on the move. After being taken to the nearest village in a palm truck, hitching a ride that ended up in the ditch, hitching another ride and flagging down the ambulance on its way to meet her, Raven finally made it to the hospital, where a qualified team of medical personnel took charge of her treatment. She figures it was about an hour from the time she was bitten.
Tne fang penetrated her left calf and injected half the venom the fer-de-lance had intended. Fortunately, the other fang only passed through her denim pant leg, and barely scratched the skin. One doctor began administering the antivenin intravenously, while another drew black lines on her leg as reference points for measuring the increase in swelling. If the leg swelled up too much they would have to split open the skin to relieve the pressure on the blood vessels. At one point violent trembling raked Ravens' entire body until her teeth clattered.
The first night was miserable, but she felt much better by the next day. After seventeen days, she was released from the hospital. "They could have kept me longer," Raven recalled, "but I insisted." At home, she was an excellent patient, following her doctor's instructions to the letter. Her leg healed perfectly, leaving only a slight scar. Raven attributes her rapid and successful recovery to a combination of getting to the hospital quickly, excellent medical attention, the essential oils she used to treat the wound, and the stroke of luck that only one of toboba tiznada's fangs injected venom into her leg.
Snakebites are not a common occurrence in the jungles of Costa Rica. I live at Hacienda Barú National Wildlife Refuge on the southern Pacific coast, in the same region where Raven was walking that fateful day. I walk in the rainforest almost every day, and I usually see about half a dozen poisonous snakes annually. Most of those are fer-de-lances, commonly called the terciopelo in Spanish and occasionally toboba tiznada. Over the years, I have seen several that made my hair curl. The biggest terciopelo I have seen on Hacienda Barú was a lone female. It was in September 1988 right after a three day torrential rain. One of my workers killed her while she was trying to crawl to higher ground. We cut her open and found 63 eggs, each with a perfectly formed little serpent inside. I'm only 1.75 meters tall, but this monster was 2.32 meters long and bigger in diameter than my thigh. Just looking at her sent a chill up my spine.
Chaperos are field workers who wield long machetes to chop weeds. They see more venomous snakes than anybody, and know a lot about their habits. Serpents remain hidden from hikers and don't bite them because a person is too large for a snake to swallow and would be a waste of the precious venom. But a chapero swinging a machete, cutting weeds and brush will disturb and frighten a snake, bringing it out into the open and causing it to try to escape or defend itself. Chaperos and other workers, prefer not to kill snakes with a machete because half a snake can still crawl and bite. However, due to the nature and circumstances of their work they often have no other choice.
Many years ago, I worked at a large cattle ranch on the Caribbean side of Costa Rica. On several occasions different people, including myself, had seen a monstrous snake crossing the jeep trail at a particular location, but nobody had gotten a good enough look to enable them to identify the species with any certainty. Then one day it struck at a chapero named Pablo. He was chopping weeds near a fallen log, about 20 meters from the point where the big snake had been seen on the road.
Bringing his arm back to swing his machete Pablo saw the raised head of the terciopelo an instant before it struck. As adrenaline shot into his blood stream, Pablo's knife bearing arm swung forward with a speed and strength he didn't know he had, severing the head and a piece of neck as long as his forearm. As he swung, Pablo dodged to one side allowing the head to fly past him and tumble into the grass, lightly brushing his shirt as it went by.
The severed head and neck turned and tried to bite his foot, but its momentum had carried it too far, and the short piece of neck wasn't long enough to crawl and propel the head nearer its target. As I came riding past on horseback five minutes later, Pablo hefted the huge reptile as high above his head as his arms could reach. A big piece of tail still laid on the ground, and the severed end was so thick that Pablo couldn't close the fingers of both of hands around it. When my horse attempted to sniff the poisonous reptile, the head curled around and nearly bit the horse's nose. That snake, the biggest viper I've ever seen, measured 2.78 meters long, and its head was so big I couldn't cover it with my open hand. Three days later one of Pablo's companions killed another terciopelo less than five meters from the same log. This one was a little smaller but still over two meters.
On that same ranch a chapero named Javier customarily wore a bandana wrapped and tied around his wrist on his machete swinging arm. One day his crew of chaperos was chopping a pasture where several cattle had died from snake bite. Everyone was on high alert Exactly like the incident with Pablo, a big terciopelo struck at Javier while he was swinging his machete, and just like Pablo, Javier severed its head. But the first terciopelo had a companion nearby, and it struck at Javier while his knife swinging arm was forward slicing through the first snake.
The strike failed to penetrate Javier's flesh, but one of the fangs caught up in his bandana wrist wrap and squirted the venom uselessly into the air and onto his pant leg. Miraculously, the free fang never touched Javier's hand. Another chapero severed that second terciopelo's head a few seconds later. Both were over two meters long. Incidentally, I worked at that ranch for six years, and, even though we had over 70 employees, nobody was bitten by a snake during that time.
In the early 1980s, when we still cultivated rice on part of Hacienda Barú, we had an interesting encounter with a two meter plus terciopelo. Near harvest time, the mature grain heads attract lots of rats, and where there are rats there are snakes. On this occasion the large rice harvester was moving through the field cutting rice when one of the workers heard a thump... thump... thump against the metal fender. Suspecting mechanical trouble he looked toward the source of the thud. What he saw was a large snake flipping around with each revolution of the huge tire.
The serpent had apparently been in the rice field and struck at the tire as the machine went past, driving its fangs into the rubber tread where they stuck tightly. The terciopelo was already dead, but it still unnerved everyone to know that it had been in the field where workers were walking around and loading rice sacks. Just the size of the serpent was enough to cause bad dreams. The next day a tractor was plowing the same field in preparation for planting a second crop, and it ran over and killed that serpent's companion, slightly larger than the first one.
When a chapero kills a large snake everyone in the crew hunts for the companion, because they know its there and a danger to them all. If they don't find the second viper right away, they assume it is hiding and will turn up next time they chop that pasture, and it usually does. Campesinos or country people, have learned how to live in the same habitat as poisonous snakes, and this is one bit of accumulated lore or local wisdom that helps prevent snakebite. The only two meter plus terciopelo I have seen that was alone, or at least its companion wasn't seen, was the egg laden female displaced by the flood. All the others have been in pairs.
This may be true for other species as well. At Hacienda Barú we have had forest guards who patrol the jungle for the prevention of poaching since the late 1970s, even before the reserve became a National Wildlife Refuge. At that time I had yet to place restrictions on workers regarding the killing of poisonous snakes. I had enough trouble convincing them not to kill the nonpoisonous ones. In 1986 a forest guard, named Gregorio, saw a large black-headed bushmaster (Lachesis meloncephala,) known locally as the plato negro, which he killed with a stout stick. He wanted to bring the pit viper back for everyone see, but had work to do and wouldn't return past that particular spot for about five hours.
Gregorio knew that a reptile's muscles will continue to contract for several hours after it's death, so in order to ensure that his trophy would remain in the same place, he tied a small cord around its neck and tied the other end to a tree. Upon his return five hours later the "dead" snake was coiled up, head raised slightly in striking position, and its tail vibrating rapidly. He had to kill it again, and this time he made sure. The plato negro measured 2.2 meters in length. Five days later Gregorio killed a second bushmaster, exactly the same length, in the same location.
As illustrated by Gregorio's experience, the bushmaster is an extremely powerful serpent that can survive a beating. An old timer I met in the Caribbean told me he wouldn't even consider trying to kill a large one if he was by himself, but instead would give it a wide berth. At the Instituto Clormiro Picado, where the antivenin for the treatment of snakebite is prepared, I have seen technicians handle these snakes and milk them to extract the venom. Two men can easily handle a two meter terciopelo, but it takes three for a bushmaster.
Additionally the bushmaster's venom is extremely potent for humans. Up until about 15 years ago as many as three quarters of all the victims of bushmaster bite died even when treated. However, the antivenin has improved as have the treatment procedures, and in recent years almost all snakebite victims have been saved.
Luis Montenegro is one of those who is thankful to the Instituto Clormiro Picado, for producing the excellent antivenin that saved his life when he was bitten by a black-headed bushmaster or plato negro. One night, when Luis and two companions were looking for fresh water shrimp for fish bait, the large pit viper struck. Both fangs penetrated the inside of his right ankle and injected their poison. Luis never saw the snake, but judging by the distance between the fang marks, the doctors later estimated that it was fully two meters in length.
Fortunately, the three men had a car nearby. They went first to the clinic in the village of Matapalo, about a 30 minute drive, to look for a Doctor and an injection of antivenin. In that short time, his entire leg began hurting and blood seeped from the points where the fangs had pierced his skin. After a substantial delay, the three men determined that no help was available in Matapalo and proceeded on to the hospital in Quepos, where they arrived about two hours after Luis was bitten.
The next morning he was transferred by airplane to the Hospital Mexico in San Jose. He remembers that the first doctor to look at his leg said they would most likely have to amputate. Luis remained in the Hospital Mexico for nine months, during which time, he was taken to the operating room thirty times. With skin and muscle grafts, doctors rebuilt the tissue that was destroyed by the bushmaster's venom. Miraculously, they were able to save his leg.
When I interviewed Luis Montenegro, six years later, his right leg was much smaller than his left, and he walked with a pronounced limp. The inside of his ankle and calf was scarred and deformed. A gauze bandage was tied around the spot where the bushmaster's fangs had injected the venom. "Once or twice each month the old wound opens and pus oozes out," he told me. He has other scars on his thigh and calf where the doctors took tissue for the grafts. For over a year after his release from Hospital Mexico, Luis remained under treatment at the clinic in Matapalo. The photo of his leg and the open wound, was taken at the clinic nine and a half months after he was bitten.
If all this scares you, then you have a normal healthy fear of snakes. But it's good to keep things in perspective. These poisonous snakes expend a lot of bodily energy producing the venom that they inject into their victims. Once they inject it, several days will elapse before it is replaced, and during that time the snake can't eat, because it can't kill or digest its prey. That's the big reason why people are not in a high degree danger from a venomous snake. The snake isn't crawling around out there looking for people to bite. If it were, many more bites would occur. I know of over 100 incidences when people came within striking distance of a pit viper that didn't bite them. It has happened to me on many occasions. I often wonder how many times I have placed my foot a few centimeters from a large terciopelo and never knew it was there. The 1.6 meter serpent in the photo, is one that we detected after a guide unwittingly placed his hand within a finger's length of its coiled form.
I've lived at Hacienda Barú National Wildlife Refuge since February 1972. During that time we've taken thousands of visitors on hikes through the rainforest and had scores of employees working in and around the jungle and, to date, we haven't had a single case of snakebite. A biologist with the Organization for Tropical Studies has calculated that field researchers, with that institution, worked in snake inhabited tropical environments for over 450,000 person hours before anyone was bitten.
That scientist happened to be the one who was out in the field at 450,001 hours. There is some debate about the advisability and morality of killing poisonous snakes. Extremes range from people who think you should never kill anything, to those who kill all snakes regardless of whether or not they are venomous. In the late 1980s when Hacienda Barú was in the midst of its transformation from cattle ranch and rice farm to biological reserve, I asked a biologist friend his opinion. He replied with a question: "How many snakes a year do you kill?" When I answered "eight to ten," he said: "Do whatever you think is best. Those few snakes on a reserve this size, won't make any difference ecologically."
Another biologist friend, Jim Zook, once told me that he had an agreement with the poisonous snakes. "I leave them alone, and they leave me alone." In 1994 he was bitten by an eyelash viper in the Braulio Carillio National Park, and during treatment, had a severe reaction to the antivenin. Shortly thereafter, Jim told me that he had changed his mind and now would consider killing poisonous snakes, not because he hates them, but in his words: "I don't want anyone else to have to go through what I went through." Recently he told me that he takes more personal responsibility for avoiding venomous snakes by watching the rain forest floor more intently and wearing snake proof chaps. He no longer trusts the snakes to keep their end of the "live and let live" bargain, but he doesn't kill them either.
Nancy Ravenfeld and Luis Montenegro do not hate the snakes that bit them either. Instead, they have come to understand that these poisonous reptiles live their lives in the only way they know how. The doctors told Raven that the snake that bit her was a terciopelo, yet she describes it as being much lighter colored than any of the photos I showed her. I suspect that it was shedding it's skin. Pit vipers are said to be nervous and more likely to strike while shedding. As the skin breaks loose around the head, the snake is partially blinded and tends to strike at heat signals. This may have happened with Raven. Luis thinks he stepped on the tail of the plato negro that bit him, but he doesn't know for sure. The eyelash viper that bit Jim was lying on some foliage, and bit him when he brushed it with his arm.
I haven't seen a two meter plus poisonous snake in over a dozen years. A herpetologist who was doing research at Hacienda Barú saw one in the spring of 2000. I know where two of them hang out, but I don't care to go looking for them. Since the entirety of Hacienda Barú is now a wildlife refuge, and we no longer have farmland or pasture, we don't have any chaperos, and, for that reason, probably see less venomous snakes. We've always had a policy of not killing non poisonous snakes; now we don't kill any of them. If a pit viper becomes a pest, we will remove it to a different location, but there have been few occasions when this was necessary. I'm sure the big ones are still out there and they're certainly making babies. Maybe I'll get to see another one someday.
If you are thinking about a visit to Costa Rica and plan on doing a lot of hiking in the jungle while you're here, there are several simple measures you can take to minimize the risk of snakebite: 1.) Look in your boots before you put them on. 2.) Look before you step. 3.) Buy a lottery ticket. Why buy a lottery ticket? Because in the short time you are in Costa Rica, you will have a better chance of winning the lottery jackpot than you will of getting bitten by a poisonous snake.
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