Taiwan Today

Professor Jay Mao (毛俊傑), herpetologist and head of National Ilan University’s (NIU) Department of Forestry and Natural Resources, holds a newly captured snake gingerly in a mesh sack. The snake, a highly venomous pit viper known as a habu, glares balefully at its captor, a meter or more of coiled fury with glittering eyes in a triangular head. The snake has come to Mao’s laboratory by way of county firefighters, who were called in to remove the reptile from an area residence—a common enough occurrence in rural Yilan County, northern Taiwan. By standing agreement, the snake was then transferred to Mao’s lab at NIU. The habu certainly seems unhappy at this turn of events, but it is actually poised to make significant contributions to health and science.

First, the snake will be measured, weighed and otherwise scrutinized, a process that will provide valuable data for researchers and students at the university. More importantly, the habu will also contribute venom for the creation of antivenin—the most effective treatment for poisonous snake bites. Taiwan has more than 50 different snake species ranging from massive Burmese pythons to tiny blind creatures just 18 centimeters long. Most are non-venomous and pose no threat to humans, but Taiwan is also home to at least 10 species that are capable of delivering lethal bites. Of those dangerous snakes, some of which can be found on land and others in the sea, six are considered clinically important due to the toxicity of their venom, aggressive behavior or relative abundance.

Mao’s team will milk the habu’s venom and deliver the substance to the Centers for Disease Control (CDC). This innovative collaboration has been in place since 2009 and Mao’s team usually exceeds the CDC’s annual venom requirements, sometimes many times over. Obtaining a year’s supply of habu antivenin entails 400 venom milkings, Mao says.

The CDC program makes Taiwan one of only a handful of countries to engage in antivenin production, a complex procedure in which horses or sheep are injected with tiny doses of a specific snake venom. The donor animals then create antibodies, which are extracted after a few months and become the basis for the antivenin used in the treatment of snake bites.

Kurtis Pei (裴家騏), a professor of wildlife ecology and dean of the College of International Studies at National Pingtung University of Science and Technology (NPUST), says that Taiwan’s CDC had long kept captive populations of venomous snakes to create antivenin, but maintaining the animals proved costly and difficult. Pei, who taught Mao when the latter was an undergraduate at NPUST, says that the CDC lacked the expertise needed to keep snakes alive in captivity. “They couldn’t maintain a healthy population,” he observes. He says that the CDC also took in snakes captured by local firefighters, who are usually the first responders in human-snake conflicts, but these snakes “usually [had] a short life span of one to three months. [The CDC] was constantly needing to receive new snakes.”

This put the government agency in the awkward position of being involved in the deaths of protected species, a category to which most of Taiwan’s venomous snakes belong. The CDC called in Mao and Pei as consultants as it endeavored to find a way to prevent the death of more snakes while ensuring sufficient supplies of antivenin.

In 2009, the CDC decided to outsource parts of the antivenin production process. While CDC labs still produce the end product, county firefighters collect the wild snakes, Mao and NIU provide the milked venom and NPUST manages the horses and sheep. NIU is now the CDC’s primary supplier of venom from all six clinically important venomous snake species in Taiwan.

After the venom is collected, Mao’s graduate students return the snakes to their natural habitat. “We are trying to reduce the number of snakes in captivity,” he says. Whether as a result of that effort or other factors, researchers have noted that some snake populations have risen in recent years. In fact, Mao’s research indicates that many of Taiwan’s most venomous snakes actually thrive in close proximity to human development. Rice paddies, with their large populations of fish and amphibians, provide excellent hunting terrain for many-banded kraits and Chinese cobras, while habu thrive on farmland and in low-density residential areas. Mao’s data indicates that areas with a population density of around 3,000 people per square kilometer are an ideal habitat for many snake species.

Meanwhile, the freestanding concrete houses that characterize much of rural Yilan County also provide a source of heat for these cold-blooded creatures, making such homes an irresistible resting place on chilly nights. “If you provide prey for them here [in rice paddies] and heat resources there [in concrete homes], then snakes will congregate in these areas,” Mao says.

Catch and Release

It is no surprise, therefore, that snakes are often found in Yilan’s freestanding homes. Mao’s researchers work closely with county firefighters, training them how to more effectively and humanely remove the creatures from such residences. The result is that firefighters are now able to catch snakes without harm and house them safely at fire stations until NIU researchers can collect them. The big Taiwan habu in Mao’s mesh sack and two smaller members of the same species in Mao’s lab, for example, were captured in houses or buildings, then held at area firehouses until the NIU collectors could make their weekly rounds. “Three [habu] is a typical number,” Mao says, adding that his researchers retrieve more in some weeks. In 2012, Yilan firefighters captured 121 Taiwan habu, all of which ended up at Mao’s labs for examination. After that, the animals were either released into the wild or, if release was not possible for various reasons, retained in the lab. Not all of the snakes captured by county firefighters are dangerous, but of the total of 1,100 snakes captured in 2012, 90 were many-banded kraits, one of the world’s most venomous snakes, and 47 were Chinese cobras.

The treatment venomous snakes now receive while being captured or kept in local fire stations stands in stark contrast to past years, when snake-catching tools included long-handled scissors-like instruments with vicious serrated blades that often crushed a snake’s vertebrae or killed them outright. “Before our training, [firefighters] preferred to use fire to push the snakes out, or streams of water to wash them out,” Mao says. Problems for the snakes did not end with capture, either, as firefighters ignorant of snake biology or behavior would sometimes put different species together in the same holding bin, which generally resulted in dead snakes. Today, with imported equipment provided by the Yilan County Government and training from NIU, firefighters are far more adept at handling snakes safely and humanely. Mao says the response to the program has been good, particularly among younger firefighters. “We have a very good relationship with every fire station,” he says.

The cooperative effort benefits all parties involved. Yilan’s firefighters gain the necessary training and equipment they need to do their jobs more effectively, allowing them to dispose of a prickly problem with little fuss. In turn, NIU gains access to vital research subjects and data, which, as Mao says, helps researchers “better understand our biological resources and monitor different locations.” For its part, the CDC obtains a regular supply of venom to treat snakebite victims.

Snake venom is a potent cocktail of toxic proteins that work on the victim’s heart and bloodstream in the case of hemotoxins, or on the brain and nervous system in the case of neurotoxins. Some snakes produce both kinds of venom, which they generally store in their cheeks and inject into the victim through hollow, hypodermic-like fangs. Sometimes the potency of the venom can be mitigated by either the physiology or behavior of the snake. If a snake strikes to defend itself as opposed to hunting, for example, the bite may not release any venom at all. In the case of the many-banded krait, which has extremely dangerous neurotoxic venom, the animal is generally considered docile and has short fangs that actually inject very little venom into the victim. On the other hand, the hemotoxic venom of the Taiwan habu is less deadly, but the snake is notoriously aggressive and has long fangs that inject up to 200 milligrams into a victim, causing great pain and damage to blood cells and organs.

“The importance of milking snakes for venom and the resulting production of antivenin cannot be underestimated,” says Hans Breuer, a German translator and amateur herpetologist who formerly lived in Taiwan and, along with expatriate Bill Murphy of the United States, created the website Snakes of Taiwan. “As small as it is, Taiwan is one of the very few countries that actually produce their own antivenin. No mean feat,” he says, referring to the laboratories, livestock and snake venom required to make that substance.

Minimizing Conflicts

Surging development in rural counties such as Yilan means that more people are living in areas that were once the exclusive domain of Taiwan’s wildlife, including its venomous snakes, leading to more human-snake confrontations. Mao says one way to minimize conflicts with snakes and other wildlife is to concentrate homes in smaller areas, while leaving larger surrounding areas undeveloped. The plains of Yilan, like the western plains of Taiwan, are characterized by a repeating pattern of homes surrounded by fields and rice paddies, resulting in a patchwork that provides ideal habitat for snakes—and human-snake confrontations. “We must rearrange our land development and push all of the houses together to keep the larger environment open,” Mao says.

Also essential is raising awareness of the vital role venomous and nonvenomous snakes play as some of the top predators in local ecosystems. Mao’s research demonstrates, for example, that snakes are essential to keeping rat and other disease-carrying vermin populations in check. Many snake species consume 20 to 30 percent of their body mass each week in rats, with some individuals devouring as much as four times their body mass weekly, which means that a lot of rats get eaten.

“If you catch too many snakes, you will increase the population of rats … and the trans-species disease problem,” Mao says. Because snakes are reptiles, and thus have a physiology that differs greatly from that of mammals, there is almost no chance that they will transfer diseases to humans. Rats, on the other hand, are strong vectors for diseases. “Snakes are a good service animal,” Mao says, adding that the data his team is gathering will “help people understand the role of snakes.” Tu Ming-chung (杜銘章), a herpetologist and professor in the Department of Life Science at National Taiwan Normal University in Taipei, backs Mao’s assessment, noting that rats are carriers of a number of potentially lethal diseases including hantavirus. Snakes provide an effective way to limit rat populations, he says.

Tu also underscores the utility of venom. “Snake venom is so complex—it has all kinds of functions,” he observes, as the substance is a key raw material used to produce a number of potent medications that treat everything from heart attacks to high blood pressure. “That’s why the snake is the medical symbol around the world,” he says, adding that researchers are also looking into using venom in treatments for Alzheimer’s disease, cancer and Parkinson’s disease.

Despite the useful roles snakes play in the ecosystem and in treating disease, most older children and adults still fear snakes, especially venomous ones. Changing that reaction is difficult, Tu concedes, as people seem to fear snakes in almost every culture worldwide. Tu’s research in Taiwan and the United States indicates, however, that children younger than 4 years old are not afraid of snakes, dispelling the notion that humans have an instinctual aversion to the animals. Instead, the fear is grounded in culture, he says, citing the Bible’s portrayal of the snake in the Garden of Eden as well as Chinese myths that cast snakes in a bad light. This year, for example, is the Year of the Snake according to the Chinese zodiac, and superstition holds that such years are more prone to bringing misfortune.

When not busy with his university duties, Tu visits elementary schools around Taiwan to dispel students’ fear of snakes. During his visits, Tu talks about the need for conserving snakes and provides living examples for the children to touch. “Once they touch a snake, they can see it’s very different than they expect,” he says, as the reptiles are not slimy, as many assume. This is the first step in the process of persuading students that many snakes “are not so terrible and are actually quite docile.”

The fear of snakes remains strong in Taiwan, however, despite the country’s great strides in environmental consciousness and conservation. “After 30 years, there’s been big progress, but not when it comes to snakes, especially venomous snakes,” Tu says. In fact, that sense of unfairness led him to make snakes the focus of his career. “Snakes are the only animals surrounded by so much misleading information,” he says. “Somebody needs to say something for them.”

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Timothy Ferry is a writer based in Taipei.

The Scary Six

While snake researchers are quick to defend their oft-maligned subjects as apex predators essential to keeping rat and other vermin populations in check, even they admit the danger posed by Taiwan’s six most venomous snake species. These are the “scary six,” the local venomous snakes that are considered clinically important by dint of the toxicity of their venom, potential for biting and relative abundance.

Taiwan habu (aka Chinese habu; Protobothrops mucrosquamatus)

This snake is considered highly venomous and reaches a maximum length of 150 centimeters. It is fairly common throughout Taiwan. Hans Breuer, co-creator of the Snakes of Taiwan website, says, “The hemotoxic venom of the Taiwan habu is less deadly than others, but the snake is notoriously aggressive.” In rural Taiwan, he says, “even the smallest medical facility carries habu antivenin.”

Hundred-pacer (aka Chinese moccasin and Chinese sharp-nosed viper; Deinagkistrodon acutus)

The hundred-pacer is the poster child of venomous snakes in Taiwan. Worshiped by aboriginal tribes and hunted to near extinction for its flesh, this medium-sized (up to 150 centimeters), highly venomous snake gets its name from the legend that victims of its bite can walk only 100 steps before dropping dead. This is hyperbole, but only just. “This species is rightly considered dangerous, and fatalities are not unusual,” Breuer says. Hundred-pacers are now rare, occupying wild areas of central and southern Taiwan at altitudes of 500–1,500 meters.

Chinese cobra (Naja atra)

Many people find it difficult to imagine that 2-meter-long, highly venomous cobras are actually fairly common in Taiwan. Farmers in southern and eastern Taiwan know otherwise, however, as they often must deal with the creatures, which thrive in farmland environments. Breuer notes these magnificent animals have both neurotoxic and hemotoxic venom, which means that untreated bites can be lethal. Fortunately, locally produced antivenin is widely available.

Many-banded krait (Bungarus multicinctus)

According to Breuer, this highly venomous snake “produces the most powerful venom of any terrestrial snake outside Australia.” It is little surprise, then, that mortality rates for victims who do not receive antivenin are as high as 85 percent. These snakes rarely bite, however, as their first impulse is to flee from confrontation. Many-banded kraits grow to a maximum length of 180 centimeters and are considered common throughout Taiwan below 1,000 meters.

Bamboo viper (aka Chinese green tree viper; Viridovipera stejnegeri)

So many naturalists who do field research report being bitten by this common viper that it is almost a rite of passage in the profession. This small tree viper grows to a length of about 90 centimeters. While not lethal, if left untreated its venomous bite can result in an ugly wound that can take months to heal. The bamboo viper is the only venomous snake not protected by law in Taiwan. While the snakes are fairly common on low-elevation hillsides in Taiwan, they are infrequent visitors in homes, as they prefer to avoid human habitation. To collect venom, Mao therefore traps bamboo vipers in NIU’s experimental forest rather than relies on receiving specimens captured by firefighters, as he does with all other venomous snakes.

Russell’s viper (Daboia russellii siamensis)

This highly venomous snake has a maximum length of 128 centimeters and lives at elevations of up to 500 meters in a very small area of southern Taiwan. Because it is so rarely encountered, the Russell’s viper is often not included in lists of clinically important venomous snakes.

—Timothy Ferry

Copyright © 2013 by Timothy Ferry