May 30, 2003
Air Date: May 30, 2003
Sound Science or Fertilization Folly?
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As carbon trading markets gear up, entrepreneurs are looking for ways to make money while helping curb climate change. Journalist Wendy Williams talks with host Steve Curwood about one scheme to sequester carbon in the seas by seeding algae blooms with iron. (11:00)
Consumer Note/Recycling Deli Containers
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Living on Earth’s Cynthia Graber reports that a national grocery chain will begin selling its deli food in containers made from corn. (01:15)
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This week, facts about Vaseline. Petroleum jelly was first patented this week back in 1872 by a New York chemist named Robert Chesebrough. (01:30)
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The Mediterranean fruitfly is one of the most destructive agricultural pests in the world. In Mexico, a program to control the medflies is raising concerns among farmers and residents. Tatiana Schrieber reports from Chiapas. (11:00)
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Wood mice use sticks, leaves and shells as sign posts so they don’t get lost as they travel through fields. Host Steve Curwood talks with Oxford University zoologist David Macdonald about the rodent road signs. (03:00)
Emerging Science Note/Bee It Hot or Cold
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Living on Earth’s Maggie Villiger reports how colder temperatures during their youths can make honey bees stupid. (01:15)
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Monterey Bay, the nation 's largest marine sanctuary, is home to more than two dozen endangered or threatened species. But some who live along its coastline are now concerned about the environmental impact that cruise ships could have on that fragile ecosystem. From Santa Cruz, California, Sandy Hausman reports. (06:30)
Life on the Hill
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Living on Earth’s Washington D.C. correspondent Anna Solomon-Greenbaum is leaving her post on Capitol Hill for the fields of Iowa and a writers’ school there. Host Steve Curwood asks Anna some final questions about environmental politics in Washington, D.C. (06:00)
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Commentator Alan Lightman reflects on the life span of humans and the ways in which the environment affects the length of our lives. (03:30)
HOST: Steve CurwoodGUESTS: Wendy Williams, David MacDonaldREPORTERS: Tatiana Schreiber, Sandy Hausman, Anna Solomon-GreenbaumCOMMENTARY: Alan LightmanNOTES: Cynthia Graber, Maggie Villiger
CURWOOD: From NPR, this is Living on Earth. I'm Steve Curwood. As the potentially devastating impact of global climate change becomes more apparent to the public, promoters are seeking ways to cash in on concern and guilt.
WILLIAMS: I think what's happening here, in some cases now, is that people are throwing out certain ideas and seeing if the world buys them. And if the world buys them, these people will make money, whether there's scientific proof or not.
CURWOOD: Sound science or fertilization frenzy. Selling the public on personal ways to mitigate global warming. Also, the cruise ship industry has been hit hard by the travel slowdown. Now, it's facing criticism over its dumping practices.
LONG: Frankly, these are large floating cities, and they have all the same kinds of effluent and pollutant streams that a city does, but without the same kind of monitoring and enforcing that cities have.
CURWOOD: Those stories and more, this week on Living on Earth, right after this.
ANNOUNCER: Support for Living on Earth comes from the National Science Foundation and heritageafrica.com.
CURWOOD: Welcome to Living on Earth. I'm Steve Curwood. Extra carbon dioxide in the atmosphere is a principal trigger of global warming, so anything that reduces it addresses the problem. The simplest thing is to use non-polluting energy such as sun, wind and the earth's natural heat. But with society so dependent on fossil fuels, science and industry are busy exploring ways to get CO2 out of the air. A tree, for example, turns CO2 into wood, thereby sequestering the carbon for decades or more. And there is money to be made in the sequestration business. Polluting companies are already claiming so called carbon credits by planting and protecting forests. And another method that's getting attention is "iron fertilization." It relies on microscopic ocean plants called phytoplankton. Journalist Wendy Williams reported on this for the Fund for Investigative Journalism. Wendy Williams joins us now.
Wendy, first tell me what do tiny phytoplankton have to do with carbon dioxide in the atmosphere?
WILLIAMS: Well, the interesting thing about phytoplankton is that they are very, very small, one cell, and they are plant-like. They take carbon dioxide out of the atmosphere. And through a process that we all heard of in eighth grade, photosynthesis, they turn that carbon dioxide into plant material and exhale the oxygen. So, the carbon is incorporated into the body of the organism.
CURWOOD: So, how does this relate to climate change?
WILLIAMS: At this moment, we have an excess of carbon dioxide in the atmosphere. Scientists and engineers all around the world are struggling to find interesting and useful ways that they can take that carbon dioxide already in the atmosphere out of the atmosphere, and tuck it away in sort of long-term bank accounts where it won't do any harm. One of the ideas that people have been playing around with for the last decade or so is to try to grow phytoplankton in the ocean, incorporate carbon dioxide out of the atmosphere that way, and then have that phytoplankton, theoretically, sink to the bottom of the ocean and hide the carbon that we don't want anymore.
CURWOOD: So, how does iron fit into all of this?
WILLIAMS: Well, one of the mysteries of the ocean has long been why certain large parts of the ocean were desert-like. That sounds funny to us because we don't imagine a desert in the ocean. It sounds like an oxymoron. But, as a matter of fact, there are large parts of the ocean where very, very little grows. And scientists have wondered for a long time why that would be so. An oceanographer named John Martin from the west coast, came along at the beginning of the 1990s and theorized that iron was the limiting factor. All of us need iron in order to have cellular processes operate in us, whether we're human beings, animals, or plants.
CURWOOD: But only tiny amounts of iron.
WILLIAMS: Only tiny, tiny trace amounts of iron. Not a very large amount but just a little trace of it is enough to catalyze the reactions and to get things going.
CURWOOD: So, the idea is that iron somehow would make more phytoplankton?
WILLIAMS: John Martin said two things. At the beginning of the 1990s, he had two interesting ideas. His first interesting idea was, if you were to seed parts of the ocean with these tiny trace amounts of iron, phytoplankton would grow there, where they hadn't grown before. His second idea was that if greater amounts of phytoplankton were to grow in the ocean, we would be able to cool the planet and control climate change. He came up with the idea, give me half a tanker of iron, and I'll give you the next Ice Age. The error was that he packaged these two ideas in one wrapper.
Now it turns out, 10 years later, that, in fact, Martin's first idea, seeding the ocean with iron, would, in fact, bring about a greater phytoplankton bloom. But what hasn't turned out is that by increasing the phytoplankton blooms, we can cool the planet. Some very recent science has shown that there are many, many other factors that feed into the system that cools the planet, not just phytoplankton.
CURWOOD: What do scientists say about this? How practical do they say this scheme might be to use iron filings to effect climate change?
WILLIAMS: Initially, three or four years ago, there were some leading oceanographers that were interested in the idea. It did look, from the research that had been done so far, as though seeding the oceans and growing phytoplankton could, in fact, help with global climate change. In the last couple of months, particularly over the last year, many of those scientists have come to say that they really don't think it's a very efficacious idea. It turns out that the amount of iron that you would need, and the amount of phytoplankton that you would have to grow, would be so considerable that it's just not practical.
CURWOOD: What would this do to the biology of the ocean?
WILLIAMS: The scientists that I've spoken with have a number of concerns about how the biology of the ocean could be affected. Inducing large scale phytoplankton blooms in the ocean could deplete the ocean of oxygen which is needed by other organisms that live in the ocean. It could create gaseous effects which might be released back into the atmosphere and heat up the atmosphere, instead of cool it off. It could upset the food chain in the ocean so that other organisms that we hadn't expected to be there and that really don't belong there might suddenly show up. It could be that by adding iron to certain parts of the ocean, we might be encouraging the wrong kinds of phytoplankton to live in the ocean, rather than the kinds of phytoplankton that normally live there. We don't actually know.
CURWOOD: One thing that you said that really intrigued me, the notion that this could perhaps make global warming worse?
WILLIAMS: Well, there is some science now to show that it could have the reverse effect. John Martin was playing around and said a half a tanker of iron will bring you the Ice Age, but some science actually researching that idea has shown that in some cases it could heat up the climate. Large phytoplankton blooms may, in fact, absorb sunlight from the sky, and then may heat up the ocean, which, of course, could heat up the climate. It could have all kinds of effects that we can't foresee.
CURWOOD: So, what else have we learned from real studies of trying to seed the ocean with iron filings, scientific studies?
WILLIAMS: Well, researchers have learned a lot of very profitable things. And every one that I spoke with, all of the researchers with whom I spoke were very enthusiastic about being allowed to go on to continue to do these kinds of small scale studies. They're learning all about carbon pumps. They're learning about ocean circulation. They need to know much, much more about phytoplankton. Phytoplankton is sort of a generic name for a number of different organisms, and we understand very little about them, why they're in the ocean, where they go, who eats them, who eats the ones that ate them. And what researchers are doing now is using this as a kind of tool in order to learn a lot more.
CURWOOD: Now, as I understand it, there is some interest in large-scale iron fertilization, iron ocean fertilization projects. Who is interested in promoting such things?
WILLIAMS: There have been several companies that initially thought that it would be a good idea. Seven different patents to date have been taken out on this as a way to sell carbon credits that might or might not be tradable on the international market. Most of them are waiting to see. I went out to California in January to talk with someone who already is out there marketing it.
CURWOOD: What's going on there?
WILLIAMS: Well, I visited with a very nice man named Russ George, who has a website, and tells people that if they want to deal with the carbon that they themselves have helped to put in the atmosphere, they can send him a certain amount of money and he'll seed the ocean with iron for them, grow the phytoplankton, and they will have dealt with their personal carbon obligations that way.
CURWOOD: In fact, do you think folks are going to get the deal that they're looking for?
WILLIAMS: Right now, there's no science that says they will. The science, basically, has panned out to say that that will not occur.
CURWOOD: Now, who oversees what folks like Mr. George and other entrepreneurs are doing?
WILLIAMS: That's one of the problems right now that we're dealing with as a nation and as a world. By not signing the Kyoto Treaty, we are opting out of the supervisory situation which the Kyoto rules are creating, even as we speak. Right now, committees under the supervision of Kyoto are working out what kinds of carbon sequestration ideas are good and healthy for the planet, and they're discarding the ones that they don't think will be useful, and that they don't think will accomplish climate mitigation.
Our country, of course, isn't involved in that right now. We have a more free-for-all kind of situation where someone is out there and throwing out an idea, and if people buy it, then they make money, and if they don't buy it, they don't make money. It's almost as though we went down to the stock market on Wall Street and said okay, you guys, what we want you to do now is to continue to trade your stocks and make your money, but we're not going to be bothering setting up any more rules for you because we don't think you really need the supervision.
CURWOOD: Wendy, explain for me, how would an entrepreneur make money by pouring iron off the side of a boat into the ocean?
WILLIAMS: There are a number of large corporations right now, both based in America and international, multi-nationally based corporations, which have what they are beginning to call carbon obligations. Most large corporations now that emit greenhouse gases understand that they will have to find some ways to control those emissions in order to have the rest of the world look upon them as positive business people. But I think what's happening here, in some cases now, is that people are throwing out certain ideas and seeing if the world buys them. And if the world buys them, these people will make money, whether there's scientific proof or not.
There are some very legitimate carbon sequestration projects out there which, under the Kyoto rules, will actually help to mitigate climate change. It's going to be very difficult for the general public to differentiate between the ones that are legitimate and the ones that really will not work but will help people make money. That's why we need a committee to help us work out the rules because individual people can't know enough to decide whether each project is legitimate or not.
CURWOOD: Wendy Williams is a freelance environmental journalist whose work has appeared in Scientific American, Science, The Boston Globe, Audubon. She received a grant from the Fund for Investigative Journalism to research global warming strategies. Thank you for briefing us, Wendy.
WILLIAMS: You're welcome. Glad to be here.
CURWOOD: And to see the complete investigative report by Wendy Williams on Russ George and the iron fertilization schemes, go to our website, livingonearth.org. That's livingonearth.org.
[MUSIC: Wimme “Iras” Gierran Zenmaster (1997)]
Russ George’s website - Planktos
CURWOOD: Coming up, in Mexico a big flap over a tiny fly. First, this Environmental Consumer Note from Cynthia Graber.
[MUSIC: Science Note Theme]
GRABER: In the first move of its kind, Wild Oats Markets, a national grocery store chain, will be replacing all its traditional plastic deli food containers with plastic made from corn. This corn-based plastic is made by taking corn starch and refining it into a sugar. The sugar is then fermented to become lactic acid. And the lactic acid is further refined to create compounds that can be used in a variety of plastic products, like food containers. Customers will be able to bring the containers back to the store where they'll be collected and sent off to an industrial composting facility.
Industrial composting facilities operate at the very high temperatures and high moisture levels needed to break down the corn-based plastic. The end product will be a rich dirt that could wind up back in Wild Oats stores for sale as compost. Wild Oats plans to introduce its new deli holders in its Pacific Northwest stores, then take the corn-based plastic containers nationwide. The makers of the containers say using corn instead of petroleum greatly reduces their greenhouse gas emissions.
That's this week's Consumer Note. I'm Cynthia Graber.
CURWOOD: And you're listening to Living on Earth.
[MUSIC: Wimme “Gierran” Zenmaster (1997)]
CURWOOD: Welcome back to Living on Earth. I’m Steve Curwood.
[MUSIC: Frankie Valli “Grease” Grease Polygram (1978)]
CURWOOD: One hundred and thirty-one years ago this week, Brooklyn-based chemist Robert Chesebrough wrote the U.S. Patent Office about his new invention.
He called it “a thick, oily, pasty substance, semi-solid in appearance, and unobjectionable in odor.” He suggested uses for his versatile goo, praising it as “a pomade for hair, a moisturizer for chapped hands, a lubricator for machinery, and a treatment for leather.” And so the world was introduced to Vasoline.
Mr. Chesebrough slipped into his greasy venture after a visit to a petroleum refinery in Pennsylvania. He was a kerosene salesman and this newfangled replacement for whale oils caught his eye, especially the residual sludge that gathered on the drilling machines. The so-called “rod wax” clogged the rigs, but workers found that it came in handy when they got burned. They used it to treat injuries.
Robert Chesebrough knew a good thing when he saw it. He filtered the tarry gunk to make it cleaner, and hit the road. He put on live shows in which he would cut or burn himself and slather Vasoline on his wounds. Then he would wow the audience by showing off scars from earlier injuries, healed by his product. The jelly formed a barrier that blocked germs. By 1874, he was selling a jar a minute.
Mr. Chesebrough lived well into his 90s. Perhaps he owed his longevity to the spoonful of Vasoline he swallowed every day of his adult life.
And for this week, that’s the Living on Earth Almanac.
CURWOOD: The Mediterranean fruit fly is one of the most destructive agricultural pests. Medflies can attack as many as 200 kinds of fruits and vegetables, and their hatching eggs can ruin tons of produce in a short amount of time.
For three decades, the United States, Mexico, and Guatemala have cooperated in a program to eradicate the bug. In Mexico it’s called the Moscamed program and it claims great success in controlling medfly outbreaks. But as Tatiana Schreiber reports from Chiapas, it’s been controversial.
SCHREIBER: The Mayan Indian coffee farm and community of Peña Blanca is just outside the Montes Azules Biosphere Reserve in southeastern Mexico. It’s some of the last remaining rainforest in the Americas. And while some environmentalists see all farming in this fragile ecosystem as destructive, organic, shade-grown coffee is considered one of the most environmentally benign ways to use the land.
[MAN SPEAKING SPANISH]
SCHREIBER: Don Manuel de Jesus Ruiz names the various shade trees that protect his coffee, and whose fallen leaves create the rich compost on the ground. Don Manuel has just one hectare, about two and a half acres, planted with coffee along with banana, guava, avocado, and citrus trees. He points to many with damaged or completely missing leaves.
DE JESUS: [SPANISH] Look at these trees! They shouldn’t be like this. They should have their normal leaves. The fumigation affected them so much. Look at those, they don’t have leaves. They are completely ruined.
SCHREIBER: Don Manuel and other farmers here are furious about what they say is a threat to their livelihoods, to their attempts to farm organically, and to the ecology of the area. Two or three years ago, medflies were detected in southern Mexico which had been free of the pest since the early 80s. The government response was to go on the offensive. The first step was aerial insecticide spraying, followed by the release of millions of sterilized medflies to halt reproduction.
From 1978 through last year, the Moscamed program’s insecticide of choice was Malathion. Agronomist Pablo Muench Navarro is director of the Institute of Natural History and Ecology for Chiapas. He says Malathion is not known to defoliate trees. But after a visit to the region, he believes the farmers’ complaints have merit.
MUENCH: [SPANISH] In my opinion, there is damage to the coffee trees and the shade trees from the spraying. In addition, it appears to me that the substances they are using are strong, strong agrochemicals.
SCHREIBER: Muench speculates that perhaps an error, like the use of the wrong concentrations of the chemical, could be at fault. Medfly officials attribute the problems to severe drought followed by heavy rains.
Aside from defoliation, farmers also complain that the spraying caused their fruits to be small, to mature and rot early, and to have dramatically reduced yields. They also point to an explosion of worms in their fruit and new outbreaks of pests such as the coffee borer.
Helda Morales is a specialist in biological control of pests. She says if large numbers of beneficial insects, including pollinators and natural enemies of pests, were killed off by the insecticide, these are just the kinds of results farmers might see.
MORALES: [SPANISH] It could have had an effect both in terms of lower yields of fruit and an increase in pests, not only with worms, like those of fruit flies, but also many others.
SCHREIBER: In 2001, the Moscamed program switched from Malathion to Spinosad, which it claims, is less toxic to non-target insects. According to U.S. EPA documents, however, Spinosad, too, is highly toxic to beneficial honeybees.
Along with concerns about the environment, some local residents fear the Moscamed program has political goals.
[SOUNDS OF BIRDS, INSECTS]
SCHREIBER: Monte Flor is another primarily Indian community not far from Peña Blanca. This part of Chiapas is home to the Zapatistas, a rebel movement that staged a military uprising in 1994. Zapatistas here have formed their own autonomous municipalities, refusing government aid.
[MAN SPEAKING SPANISH]
SCHREIBER: Olivio Morales is mayor of Monte Flor. He says the community received no notice of the spraying. He believes the Moscamed program is part of a government effort to weaken the Zapatistas by destroying their crops.
MORALES: [SPANISH] They did this with a political motive, because this way they could get the communities to stop resisting. Because when you don’t have anything to eat, well, you have to take the handouts of the government. And the communities here have always refused to take handouts. We have been in resistance, not receiving anything. It was part of a strategy of low-intensity war from the beginning.
SCHREIBER: The Moscamed program is funded largely by the U.S. Some farmers in the area think its goals are economic more than political, part of a plan to destroy their crops so U.S. farmers can take over their markets.
In Monte Flor and another local town, residents are so angry with the program that at one point they detained three of its trucks. The workers were let go but residents held the trucks for several months, demanding that the government compensate them for the damage they blame on the program.
So far, no compensation has been awarded, and Moscamed officials deny the program has any mission other than control of the fruit fly. They admit, though, that their efforts to inform communities of what they are doing have fallen short.
[VIDEO SOUNDTRACK IN SPANISH]
SCHREIBER: The new education sponsored by Moscamed uses videos like this one to explain the program’s goals, methods and accomplishments. There is also a website and pamphlets, keychains, T-shirts, and baseball caps to be given out by brigades sent to work in the affected communities. Part of Moscamed’s strategy is to use non-chemical pest control, but this too has been met with public mistrust. Its airplanes fly low, releasing millions of sterilized fruit flies in paper bags. The idea is that they will mate with the wild flies, which will then fail to reproduce.
Rumors are rampant that the planes are actually releasing rats, snakes, and even spores of coffee rust, a serious coffee plague. To counter the misinformation, the program offers tours of the sterile fly production facility.
FEMALE: [SPANISH] Because the plant houses fertile flies, we have to shower and don lab coats before we can enter.
[SOUNDS OF INDUSTRIAL WORKPLACE]
SHCREIBER: Inside the plant, the smells are intense.
MALE: [SPANISH] The smell is from pheromones. It’s the substance produced by the male to attract the female to copulate. It’s a very strong smell and since here we have a massive number of males, it accumulates and the smell gets even stronger.
| A handful of Mediterranean fruit fly larvae. The Moscamed facility breeds the flies for the sterile insect control program in Chiapas, Mexico. (Photo: Tatiana Schreiber)
SCHREIBER: Each room of the plant houses a different stage in the insect’s life cycle: mating, producing eggs, developing larvae, changing into a pupa, emerging as an adult fly, and starting all over again. At the end of the process, the pupas are irradiated to sterilize them. Then, 500 million a week are released by air over the region’s coffee farms where they emerge as adult flies.
The efforts of the Moscamed program have moved the boundaries of the flies’ territory some 20 miles south of the border into Guatemala. The long-term mission is to eradicate the fly throughout Central America.
[MAN SPEAKING SPANISH]
SCHREIBER: Ramon Jarquin is a doctoral student in ecology and sustainable development who has worked extensively with farmers in the area. He believes the Moscamed program is necessary to stop the spread of the fruit fly, but he also thinks there should be serious study of the farmers’ complaints. Such a study, he says, would have to include the coffee farmers themselves, because years of Moscamed activities without efforts to involve residents led to the current impasse.
Jarquin says it’s not only a question of ecological damage or health effects. In the political context of Chiapas, Moscamed’s activities are seen as a violation of farmers’ human rights.
JARQUIN: [SPANISH] The airplane represents a violation as far as the right to use the land. People feel their sovereignty has been jeopardized. It’s as if they took the roof off our house and started observing us like puppets.
SCHREIBER: Moscamed officials, though, insist that the complaints about the program are unfounded. They say leaders in the indigenous communities are using the program as a wedge to gain political support. Still, Luis Salmeron Zamora, subdirector of field operations for Moscamed, says the current policy is not to enter communities that don’t support the program.
SALMERON: [SPANISH] First, we ask them permission, and if they don’t give us permission, we don’t do any work.
SCHREIBER: That statement is refuted by farmers who say they haven’t been consulted. But while there is dispute about this, Salmeron says eventually agreements will need to be reached, because a severe outbreak of the medfly would be disastrous.
SAMERON: [SPANISH] If we didn’t fight the medfly here in Chiapas, we’d run the risk that 10 million tons of fruits and vegetables would not be sold, that 4.2 million acres of orchards wouldn’t be cultivated. Annually the value of that lost production, if we didn’t combat the Mediterranean fruit fly, would be $3.5 billion dollars.
SCHREIBER: Salmeron says the program is relying more and more on sterilized flies to attack the medfly problem. They are also breeding a parasitic wasp that kills medflies, and incorporating this technique into their range of eradication strategies. But some farmers here say medfly populations could be kept very low through diligent collection and disposal of affected fruits, and an effort to keep populations of beneficial insects healthy.
But for now, the spraying and insect drops continue. The public relations campaign is in full swing. And residents in several jungle communities still wait for the compensation they say they are due.
For Living on Earth, I'm Tatiana Schreiber in Chiapas.
[MUSIC: West African Balafon Ensemble “Farfina” The Pulse of Life Ellipsis (1992)]
CURWOOD: The sun was high in the sky when we spotted him low in the grass on the African savannah. Crouched, tail twitching to and fro with a menacing rhythm, a huge leopard was eyeing a herd of passing water buffalo.
Water buffalo are some of the most dangerous animals in the African wild. They have such a hard helmet of horn that even a hunter with a high-powered gun faces doom from a charging buffalo, unless his first shot is expertly placed. Most people don’t know buffalo are so dangerous, my guide told me. That’s why big game hunters are more likely to get hurt by a buffalo than by a lion in the wild.
The big cat does know the strength of the African buffalo, and was not interested in taking on a single adult, never mind hundreds of hooves and horns. But, said my guide, there might be a chance that a calf would stray from the herd. Or perhaps an elderly straggler would offer some “pickins”.
And, indeed, as the leopard crept closer to the herd, a calf broke away. The leopard tensed. His tail froze. Then, with a seemingly casual air, a large cow nudged the youngster back inside the herd.
The leopard noticeably slumped, and then resumed his vigil. He would eat, sometime, if he could just be patient.
You, too, can get a chance to see a big cat on the hunt if you become the lucky winner of the Living on Earth ultimate safari. Thanks to HeritageAfrica.com, you and a companion will see some of Africa’s finest wildlife habitats, such as Kruger and the Serengeti.
To find out how to win, go to livingonearth.com. That’s livingonearth.com, for a chance for the trip of a lifetime.
ANNOUNCER: Funding for Living on Earth comes from the World Media Foundation.
CURWOOD: Biologists have known for some time that wood mice have excellent navigational abilities. Now, new research suggests one reason why. These little rodents build themselves road markers out of leaves, twigs, and shells.
David MacDonald heads the Wildlife Conservation Research Unit at Oxford University. He first observed this phenomenon in the wild, and he wanted to see if the mice would repeat the behavior in the lab.
MACDONALD: We put the wood mice in a pretty simple arena, provided them with a nest box and some food, and absolutely nothing else at all except some plastic disks, just small bits of plastic. And lo and behold, we found that they went to a lot of trouble to pick up the plastic disks and carry them around, as if they had a deliberate purpose in mind.
CURWOOD: So, what was this purpose?
MACDONALD: Well, it seems that they were doing exactly what you and I would do if we dropped our car keys in the lawn, and then the telephone rings in the house. You’d put a stick in the ground, or some marker in the ground to remind you where the keys fell, so you can continue your search later.
And it looks as if that is precisely what these wood mice are doing. They carry a little disk around with them when they find an interesting place where there are some seeds or whatever to forage for. And then they put the disk down.
And whenever they are disturbed--and you must remember, these are very nervous creatures. They are just always jumping around, being fearful of predators and so forth. But when they have been disturbed, then they find their way straight back to the little road sign, to the marker, just as you would if you had dropped your car keys in the lawn.
CURWOOD: Why do the mice need these signposts?
MACDONALD: Well, most of the time these animals are on farmland, particularly foraging, for example, through cereal fields, cornfields. And so it must be like finding their way through, almost, an ocean of uniform habitat.
And, as I say, they are such nervous little guys that every few moments they are running to the left and to the right from some false alarm, in case a weasel or a hawk is going to strike them. And as they forage, rather interestingly, every few moments you see them stand up on their hind legs and look over their shoulder, as if drawing a bead on where the plastic disk is just so they don’t get disoriented or lost.
CURWOOD: What other animals use these kinds of road markers?
MACDONALD: Well, Steve, as far as we are aware, there’s certainly one other species, namely humans. On the other hand, looking through the literature, there is just no evidence at all of any other mammal species doing this. Now between you and I, I actually expect lots of species do it but nobody’s ever noticed it before. So, so far, the list is only two species long.
Of course, part of the interest is these are very, very familiar animals. Just like the white-footed mouse is familiar in North America, these guys are ten-a-penny in farmland in the U.K. And it’s rather exciting to find such an unexpected and intriguing adaptation in an animal that is very familiar. It shows you, you don’t have to go to a far-off land to watch a charismatic and rare species in order to find out something interesting.
CURWOOD: David MacDonald heads the Wildlife Conservation Research Unit at the University of Oxford in the U.K. Thanks so much for taking this time with us today.
MACDONALD: It’s a pleasure.