COSTA RICA 2005 FIELD TAPE SD DUB
KEYWORDS: AMPHIBIANS; BIRDS; BUTTERFLIES; CLIMATOLOGY; COSTA RICA; DIETS; DISEASES AND DISORDERS; DOGS; ECOLOGY; FROGS; GLOBAL WARMING; LIZARDS; MUSEUMS; PLANTS; POISONS; POPULATION; REPTILES; SQUIRRELS; SUN; TOADS; TREES; WILDERNESS
FTG FOR BILL BLAKEMORE CS VO ON EXTINCTION OF FROGS AND BUTTERFLIES / INTV W/ ALAN POUNDS, MONTEVERDE CLOUD FOREST PRESERVE AND ACCOMPANYING B-ROLL
DR. ALAN POUNDS' LECTURE ON EXTINCTION IN COSTA RICA
INTERVIEWER 02;00;17 So, what are you looking for here and how does it fit into your overall study.
POUNDS 02;00;20 (muffled) Most of the moisture that arrives here comes from the form of clouds and mist and we're interested in how large scale -
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INTERVIEWER 02;00;28 You ready? So, what are you looking for here, how does it fit into your overall study?
POUNDS 02;00;32 Well, most of the moisture that arrives here comes in the form of clouds and mist. So, during much of the year the forest is bathed in clouds and mist. We're looking at how those patterns are changing. We're looking at how the change (breaks off)
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POUNDS 02;00;55 Okay, so most of the most of the moisture that comes here comes in the form of clouds and mist. So there's a big cloud bank which sits on top of the mountain during much of the year and keeps the forest wet under normal conditions, but with global warming we're looking at changes in that cloud behavior. We see trends in the frequency of mist in the forest for example. And a lot the biological changes are associated with the changes in mist inputs, including the disappearances of species like the golden toad and the Monteverde harlequin frog.
INTERVIEWER 02;01;27 What are some of the exact - tell us about some of those examples where you've been able to match changes in one with changes in -
POUNDS 02;01;33 Well we see that the warmest, driest years are associated with the downturn (breaks off)
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POUNDS 02;01;48 'Cause there was a large population crash, or a large collapse of the entire amphibian fauna in the late 1980s. So, like 1987, 1988. And since then we've seen a number of downturns in surviving populations. They appear to be increasing for awhile and then we have another downturn. And if you look at a series of these events, they're associated with these warm, dry years. So years where there's relatively little mist reaching the forest. So it varies a lot from year to year.
INTERVIEWER 02;02;31 Are you able to compare the mist measurements now with what they used to be here?
POUNDS 02;02;36 Well, we don't have long term measurements for mist. So - now this is going to be hard to explain.
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POUNDS 02;03;22 So, much of the moisture that the forest receives is in the form of clouds and mist. So, there's a big cloud bank which sits on top of the mountain during much of the year and helps keep the forest moist, even during the dry season, which runs from January to the end of April typically. But we're seeing changes in the amount of mist coming in, and associated with these changes in mist, we see changes in biology. We see changes in the distribution and abundance of birds, reptiles, and amphibians including (breaks off as wind picks up)
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POUNDS 02;04;07 (picking up from before) So, associated with the changes in mist, we see changes in the distribution and the abundance of populations of birds, reptiles and amphibians. And we've seen the disappearance of whole species of amphibians like the golden toad and the harlequin frog. And these patterns are related to the changes in moisture inputs.
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POUNDS 02;04;55 So, if you look at the data you see evidence that there's a change in the amount of mist that the forest is receiving over time. And associated with this change, we see changes in the distribution and abundance of populations of birds, reptiles and amphibians, including the extinctions of whole species, like the golden (shot ends)
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POUNDS 02;05;24 So, much of the moisture inputs to the forest are in the form of clouds and mist. And we see changes in the patterns of that. We see a reduction in the amount of mist coming in (shot ends)
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POUNDS 02;05;37 - birds, reptiles, amphibians. And, including the extinction of whole species of amphibians like the golden toad and the harlequin frog - (shot ends)
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02;05;45-02;08;40 Wind in the trees as the sun sets. Very pretty.
02;08;40-02;09;13 Shot of Dr. Pounds indoors through a rainy windowpane. Visually interesting shot.
02;09;13-02;10;17 Exterior pan of the research station, zooms in on window where Dr. Pounds sits inside.
02;10;17-02;10;37 Shot of Dr. Pounds at the computer. Dog peers through the window from outside.
02;10;37-02;19;01 Shots of Dr. Pounds at the computer. Includes medium shots, close-ups and extreme close-ups of Dr. Pounds, the computer screen. Also a few shots of other items around the office.
02;19;02-END Close-ups of Dr. Pounds' slides as he explains them. Quality of the shots is very good - many will not be noticeable as reproductions.
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POUNDS 02;19;02 (off camera, describing slides) This is just a shot of the Caribbean slope, so you can see clouds forming up on the mountains. This is the location of Costa Rica, somewhere south of Florida. This is just a shot to tell people how the forest is bathed in clouds and mist. It's very rich in epiphytes - plants that grow on top of other plants, especially trees. So you can see a one-day orchid in this picture and a (SOUNDS LIKE: FORM MEAL LID). So this is the question that we've been attempting to address: Is global warming already contributing to the extinction of species. This was a thrilling sight to see back in the early 1980s: golden toads gathered at a breeding pool. Here's a group of males waiting for females to arrive. You can actually see one female up at the top there, I believe.
POUNDS 02;20;52 (off camera, describing slides) So, typically the males would arrive first. So when the females would come in, you would have quite an orgy. So, if you're having trouble making things out, these are the female's legs right here.
INTERVIEWER 02;21;15 That's a little risqué for late-night, obviously.
POUNDS 02;21;20 (off camera, describing slides) (laughs.) Rough sex in the cloud forest. Shall we go on to another one? So this picture shows quite nicely the difference between males and females. So this picture shows quite nicely the difference in coloration between males and females. And because there were - let me try that again. There are always more males than females, as I was saying, so there was a lot of competition for access to mates. And the males would sometimes get rather desperate. You can see that the male on the upper left here has fallen over the tree root. But they get it right sometimes as you can see from the pair in the lower center. And then they would lay these nice strings of overly large eggs for a toad.
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POUNDS 02;22;26 So the tadpoles that hatch from these eggs could develop all the way into a toad without eating if need be. That may be an adaptation for living in temporary pools that didn't contain a lot of food. Of course, the sad part of the story is that the golden toad hasn't been seen for a long time. In 1988 - Well, let me back up and say that in 1987 Marty Crump was trying to study the behavioral ecology of the species and she counted approximately one thousand five hundred golden toads at the principle known breeding site up on Brillante. And then in 1988 and again in 1989, only a single male appeared there and since then we haven't seen any at all. So throughout the 1990s and into the new millennium, the golden toad has been missing. So we're afraid that it's extinct. And the same is true of the Monteverde harlequin frog, last seen in 1988. This used to be a very common species in the cloud species in the cloud forest. So, it's a member of the Toad family. They breed in streams - mountain streams. The tadpoles have suckers that allow them to hold onto rocks.
INTERVIEWER 02;23;48 And why do you think they went extinct?
POUNDS 02;23;52 Same reason everything else did.
INTERVIEWER 02;23;55 Whatever that reason is. This went extinct the same year, basically, you said it -
POUNDS 02;24;01 This species and the golden toad both declined by about 99 percent the same year. Along with a lot of other populations.
INTERVIEWER 02;24;18 Why those colors?
POUNDS 02;24;20 This is warning coloration. Harlequin frogs contained tetrodotoxin, a very potent nerve poison, in their skin. So this was a warning that they weren't good to eat.
INTERVIEWER 02;24;36 Are they found anywhere else?
POUNDS 02;24;38 The genus is found throughout the highlands of - well, throughout much of Central and South America and up in the mountains.
INTERVIEWER 02;24;47 But this species?
POUNDS 02;24;49 This species was known only through Monteverde, so this is endemic to Monteverde.
INTERVIEWER 02;24;56 Do you believe in your heart that it's extinct?
POUNDS 02;25;02 Well, we haven't seen them since 1988 and they used to be very easy to see. So they were quite visible because they stayed out during the daytime. They're day-active and they're not at all skittish. Not at all afraid of people, so that you can walk right up to them and they don't hop away very quickly. So they were very easy to find during much of the year, so I think if they were out there, we'd be seeing them. There are some frogs that are very secretive, that stay hidden much of the time, but harlequin frogs were very easy to see.
INTERVIEWER 02;25;34 Is that because they're poisonous?
POUNDS 02;25;37 That's the kind of pattern of behavior you see in species that have defenses of that sort. They're not - they don't show a lot of fear of predators.
POUNDS 02;26;06 This is the golden-eyed leaf frog, which also declined - disappeared from Monteverde. It still survives in other parts of Costa Rica, including in the Central Valley.
INTERVIEWER 02;26;19 [unintelligible interruption].
POUNDS 02;26;19 .near - in San Jose. We haven't seen them here since the late 1980s, but you can still find them in some parts of Costa Rica. But this is a Costa Rican endemic. So it's found only in this country.
INTERVIEWER 02;26;39 What would be your guess as to the age of the species? Golden toad and Monteverde harlequin?
POUNDS 02;26;47 Those are tough question. You'll have to ask a geneticist or paleo-ecologist about that. I don't know how old the species was. I haven't been around long enough to give you a good answer.
INTERVIEWER 02;27;04 Could be a million years?
POUNDS 02;27;05 Um, I don't know.
INTERVIEWER 02;27;09 Nobody knows?
POUNDS 02;27;10 Well, there's - Yeah, most species of amphibians are quite old, but I would suggest you ask that question to someone who's been looking at the genetics of these and trying to get an idea of how long they've been around. But, yeah they could be a million years old. Museums have specimens - I don't know - I don't know.
INTERVIEWER 02;27;37 Are they all in alcohol? Are some of them dry?
POUNDS 02;27;41 They're in alcohol or in formalin. But you can extract DNA to do genetics. That's the reason we know the species of harlequin frog that occurred in Monteverde was different from other species - other populations that we though belonged to the same species. That's thanks to work by people in Panama.
INTERVIEWER 02;28;14 [referring to the golden-eyed leaf frog, which is still on the screen] This one's endangered?
POUNDS 02;28;16 Yes. You can still find them in pretty good numbers. In some populations where they've declined - dramatically at a lot of sites, including Monteverde.
INTERVIEWER 02;28;28 I thought this was a preserve. It's funny that they're not found here anymore, they're found in San Jose. It's kind of ironic, isn't it?
POUNDS 02;28;36 Well that's the kind of evidence that you see that it's not habitat loss that's causing these disappearances. You see populations disappear from protected areas, and yet survive in fragmented areas sometimes. So habitat loss - it doesn't explain the dramatic losses that we're seeing. So this is a section of skin showing the fungus that we were talking about before the - which is an important cause of mortality.
INTERVIEWER 02;29;16 How does this one work on the skin?
POUNDS 02;29;19 Well, it produces zoospores that infect frogs. Zoospores from the same individual can re-infect the same frog and so you can get a - you can build up a very severe infection, which can be lethal.
INTERVIEWER 02;29;42 Does it kill the frog because it makes the skin incapable of breathing and drinking?
POUNDS 02;29;47 Well, the fungus as I understand it, feeds on keratin in the skin and it can interfere with the process of taking up water. It's not terribly clear whether it also produces toxins that affect the frog. And again, I'm not an expert on this fungus, so there are people who could tell you much more about it than I can.
INTERVIEWER 02;30;15 Chytrid fungus?
POUNDS 02;30;16 Right. This is an example of a dead frog. This is a dead harlequin frog.
INTERVIEWER 02;30;36 From what year?
POUNDS 02;30;37 This was taken somewhere in South America, so this picture was given to me by a friend. So I don't have detailed information on it.
INTERVIEWER 02;30;44 What killed it?
POUNDS 02;30;46 Ahh, this was included in this talk to represent death by this chytridiomycosis, but I'm not sure if it was confirmed in this particular specimen. I think it - I think it may have been. So it's - the pattern is that biologists have gone into stream sites and have found numbers of dead and dying frogs. And then when they examine them it turns out that they have this chytrid fungus. But we think there's more to the story than just the fungus, because we've seen declines in other kinds of organisms, including reptiles,and it seems unlikely that a fungus that attacks the moist skin of amphibians would also attack reptile skin, so we think there's more to the story than a single disease. And, of course, we're also seeing these patterns that indicate that climate is also playing a role.
INTERVIEWER 02;31;53 What kinds of reptiles are seeing a decline?
POUNDS 02;31;56 Ahh, anole lizards - little forest-dwelling lizards. Like - something like this [a new slide pops up]. This isn't one of the species that has declined here. This is one that actually has been decreasing in abundance at this elevation.
INTERVIEWER 02;32;18 Why do you think that is?
POUNDS 02;32;20 Well, we think it's part of the same phenomenon - climate change. You see - you see some species that are declining and disappearing from this elevation and others that are moving in.
INTERVIEWER 02;32;33 They're moving up from lower elevations?
POUNDS 02;32;35 Right. So you see species that previously occurred in warmer, somewhat drier sides of the Pacific slope that are moving up. In this case, this is a species that occurred on both slopes at lower elevations, that's been increasing in abundance at this elevation. [a slide of a bird comes up]. And the main pattern we see with birds is an upslope movement of what we think of as Cloud Forest-intolerant species, like the keel-billed toucan, which ordinarily is found in lowlands and foothills. But since about the 1990s, we've had them breeding side-by-side with quetzals, with the resplendent quetzal. This is an adult male.
INTERVIEWER 02;33;28 Tell us a little bit more about how this one has moved up into the Cloud Forest
POUNDS 02;33;34 Well, you don't think of this - this kind of bird. Well, back in the - Let's see - how can I explain this? When Michael Fogden started collecting data, in the late 1970s, this bird didn't occur at this elevation. You could only find it further down the mountain slopes. So, it's a species which is characteristic of lowlands and foothills. But since around the mid-1990s, it's been in this area. So you'd have breeding pairs. You'd have them nesting side-by-side with resplendent quetzals, like this one. This is a bird that symbolizes Middle American cloud forests.
INTERVIEWER 02;34;24 What is that?
POUNDS 02;34;25 This is a resplendent quetzal. It's a free-eating bird, member of the Trogon family.
INTERVIEWER 02;34;35 And this is normal up here in the Cloud Forest?
POUNDS 02;34;37 Yes. So, this is part of the original Cloud Forest breeding fauna. So we worry about how they may be affected by these other things moving up. Obviously you can't just keep adding species to a habitat without having ecological repercussions.
INTERVIEWER 02;35;56 Do they eat the same things as, like, toucans?
POUNDS 02;34;59 There certainly is a lot of overlap in their diets. And they also nest in dead snags. We worry about resplendent quetzals because in Monteverde, they are occurring near their lower elevational limit. So they are a species that could very easily be affected by climate change. And we've seen a decline in their numbers over the years, so we're concerned about this one. We have seen mammals moving up the mountain as well, like this variegated squirrel. So that it shows the same kind of pattern that previously was found only in premountain life zones, but has been moving up to this elevation. Here's more clouds forming over the Caribbean slope.
POUNDS 02;36;21 This is just a graph showing the trend in the number of dry days. These are data from standard rain gauges, which underestimate the kind of wind-blown mist and cloud water we've been talking about. But they do capture some. So, when a rain gauge contains nothing, you know that there was very little mist on that particular day, because it at least would ordinarily collect - at least show a signature of a mist event, even though it wouldn't give you an accurate measurement of the amount of moisture coming in. So here we're looking at the number of dry days over time. So what you can see is that there's a clear upward trend, though a lot of variability around that trend. And that variability is in large measure related to El Ninõ. So you can see different El Ninõ events. Like, you can see the '82-'83 El Ninõ here, the '86-'87 - you can see this long El Ninõ in the early to mid-'90s and then the one in the late '90s.
INTERVIEWER 02;37;36 So if El Ninõ explains it, why global warming?
POUNDS 02;37;40 Well, what you see though is that there's a - the effect of El Ninõ is superimposed on a longer-term trend. So here, if you put sea-surface temperature you can see - you can see the effect of El Ninõ. The blue graph - the blue line on the graph represents sea-surface temperature, looking at departures from a long-term mean for the equatorial Pacific. So this is measured - hundreds of, well something like 800 kilometers from here out in the middle of the equatorial Pacific. But these are just - this is just El Ninõ region temperatures. What you can see is the signal of El Ninõ and you can see that there's a correlation with the -
INTERVIEWER 02;38;30 Spikes.
POUNDS 02;38;31 Mm, hmm. But once you take this into account statistically, you're still left with a drying trend. So this graph - this graph shows this drying trend that's left over after you take into account El Ninõ.
INTERVIEWER 02;38;49 In other words, over all it's - on average it's increasing.
POUNDS 02;38;52 Right. So El Ninõ produces a lot of noise, but it's also very important noise because it's - you can get major extremes, especially when you have this superimposed on a changing baseline. So it's the overall pattern is moving towards a drier sort of conditions. Then when you get an El Ninõ event superimposed on that you can get unusual extremes. So, but if you ask what's causing this underlying long-term trend, you can get an idea by looking at the global warming signal. So here we're looking at temperature going back to the mid-1800s.