Snake Crossing
CURWOOD: For the past 31 years people driving through Shawnee National Forest in southern Illinois have had to yield – not to pedestrians but to rippling reptiles. Every spring and fall for two months at a time, the U.S. Forest Service closes down Road 345 to let past thousands of migrating snakes. This single-lane gravel road is a major hurdle for snakes leaving their warm weather swamp for winter hibernating dens. Herpetologist Scott Ballard, with the state’s Department of Natural Resources, has walked Road 345 many times to monitor snake crossings and says he’s seen ‘em all.
BALLARD: Mostly, the largest population of snakes down there are water mocassins, also known as cottonmouths, that are venomous. But you can also find things like red milk snakes, western ribbon snakes, copperheads, timber rattlesnakes, earth snakes, brown snakes, king snakes. A number of different species use that road.
CURWOOD: Sounds like a pretty rough crowd.
BALLARD: Yeah, it’s – if you’re faint of heart with snakes it sometimes can be alarming. But even though they use this road quite a bit to migrate across, the road is two and a half miles in length, and if you walk the entire length of that road and see 20 or 30 snakes, you’ve seen a lot. When we were down there a couple weekends ago we were seeing a snake about every 50 feet. And it used to be one of the annual rites of spring for the locals to go down and see how many snakes they could run over in their cars.
CURWOOD: Uh, really.
BALLARD: Mm, hmm. And it’s been a big educational process to educate people in the values of snake conservation.
CURWOOD: And the value of snake conservation, for those who are skeptical listening to you right now?
BALLARD: Well, the best way to describe it to people is one average sized snake can eat up to nine pounds of rats and mice in a year. And nine pounds may not seem like a lot, but it will fill up a pillowcase. So, what I tell people is, every time you kill a snake in your yard or in the woods, it’s almost like dumping a pillow case full of mice out there because that’s pretty much what you did. And mice can carry things like rabies and hanta virus and stuff, so these snakes are actually keeping disease-carrying rodents under control for us.
CURWOOD: Which species tend to cross the road the fastest?
BALLARD: It depends on temperature. I’ve seen the cottonmouths go across the road pretty quick. But if it’s warmer, and that roads really hot and it’s warm on their belly, they’ll move across it faster than if it’s cool and they want to kind of sit on the road and absorb some of that heat for a while.
CURWOOD: Tell me Scott, how often do you help the snakes out themselves get across the road?
BALLARD: Well, if I come across something that I’m doing a mark-recapture study on – like a Mississippi green water snake, we have about 50 of those animals marked down there and we’re trying to determine what their population status is – if I slow the animal down by picking it up, weighing it, determining if it’s a male or female, and then clipping scales, I will then go ahead and put it on the other side of the road that it was headed to.
CURWOOD: Scott Ballard is a herpetologist for the Illinois Department of Natural Resources. Scott, thanks for taking this time with me today.
BALLARD: Well, thank you very much for the opportunity.
CURWOOD: Just ahead: where there’s smoke, there’s a possible health risk. The fallout from the California fires. First, this Note on Emerging Science from Cynthia Graber.
Vocabulary
herpetology : a branch of zoology dealing with reptiles and amphibians爬行類學,爬行動物學
ripple (vi) 1 a : to become lightly ruffled or covered with small waves b : to flow in small waves c : to fall in soft undulating folds <the scarf rippled to the floor> 2 : to flow with a light rise and fall of sound or inflection <laughter rippled over the audience>
3 : to move with an undulating motion or so as to cause ripples <the canoe rippled through the water> 4 : to have or produce a ripple effect : SPREAD <the news rippled outwards> (vt) 1 : to stir up small waves on 2 : to impart a wavy motion or appearance to <rippling his arm muscles> 3 : to utter or play with a slight rise and fall of sound
water moccasin 1 : a venomous semiaquatic pit viper (Agkistrodon piscivorus) chiefly of the southeastern U.S. that is closely related to the copperhead -- called also cottonmouth, cottonmouth moccasin 2 : an American water snake (genus Nerodia)
pillowcase (n) : a removable covering for a pillow
hantavirus (n): any of a genus (Hantavirus of the family Bunyaviridae) of RNA viruses that are transmitted by rodent feces and urine and cause acute respiratory illness and hemorrhagic fever marked by renal necrosis
hemorrhage : a copious discharge of blood from the blood vessels
copious (adj) 1 a : yielding something abundantly <a copious harvest> <copious springs> b : plentiful in number <copious references to other writers> 2 a : full of thought, information, or matter b : profuse or exuberant in words, expression, or style <a copious talker> 3 : present in large quantity : taking place on a large scale <copious weeping> <copious food and drink>
rite (n)1 a : a prescribed form or manner governing the words or actions for a ceremony b : the liturgy of a church or group of churches 2 : a ceremonial act or action <initiation rites>
fainthearted (adj): lacking courage or resolution : TIMID
Vocabulary
1. Talking about snakes, are you afraid of snakes? All snakes? Only some kinds? How about lizards or salamanders? Supposing snakes is as small as lizards, are you still afraid of them?
2. Why are people afraid of snakes? Because they bite? Because they constrict? Because they are poisonous? Because they are cold-blooded? Some pythons are not poisonous, are you still afraid of them?
3. Comparing crocodiles with snakes, which one do you dislike more? Why? Do you know that snakes can also swim? Do you think you can walk or swim faster than a snake? Do you know how to run away from a snake, supposing a snake is chasing you?
4. What do think if we kill all the snakes in Taiwan? Do you think it is a good idea? Do you think it is going to create some ecological imbalance?