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Golden Toad

A beautiful little amphibian called the Golden Toad was first described in the Monteverde mountain region of Costa Rica in 1966, but has not been seen anywhere in the world since 1989 and is presumed to be extinct. This biological tragedy is made more alarming by the fact that this region of the Costa Rica mountains is protected as a national reserve and was presumed to be a site for species preservation, not extinction! Costa Rica has some of the most delicate and unusual ecological systems of the world. Placed at the isthmus of the junction between North and South America, Costa Rica has both a Pacific and a Caribbean coast, with a prominent North-South mountain range that serves as a continental divide, which, like that in North America, determines whether rivers flow to the Pacific or Caribbean oceans. Monteverde is near a unique regional preserve in the mountainous region North of San Jose, the main city of Costa Rica (To get there you have to drive up a 30 km road that is unpaved, very rocky and dangerous. We did it in a small four-wheel drive car, during an intense rain storm, but most others we met hired tour guides to take them up and bring them back: they looked at us like we were a little nuts).

On the Caribbean side of the mountain forest, the region is a rain forest, fed by moist warm air coming up into the mountains, driven by a warm, seasonal Caribbean current. But on the Pacific side of the same region, the forest is a cooler cloud forest, in which less rain falls, but continuous cloud formations in the canopy of the forest keeps the region damp and cool. The continuous moisture of the cloud forest is essential for the orchids and bromeliads that live as epiphytes in the tree canopy. Without a source of continuous high humidity, many of the special plant species could not survive and the unique ecology of the region would be significantly changed.

I know from experience about one aspect of this issue, as I once tried to grow Masdevallia and Dracula orchids of the type found in the tree canopies of the cloud forests in Costa Rica; I found it impossible to grow them in Minnesota unless you go to great lengths to keep the humidity at 70% or more and in the range of 60 degrees Fahrenheit at night. In Minnesota, that type of environment can only be achieved with something like the Orchidarium that is manufactured here in Minnesota, specifically to address that kind of problem. I don’t have an Orchidarium, although a primitive homemade version of one is sitting in my office, only lacking waterproofing and an internal fan. Someday I will get to it and try the same orchids once again under “cloud forest conditions.” These special orchids and bromeliads don’t just have a small regional area of distribution, but within the cloud forest they have a restricted vertical layering to their representation, where the cloudy tree top regions best meet their requirements. These orchids produce small delicate flowers which attract very specific pollinators. Pollination requirements in the forests around Monteverde are not just met by insects, but huge arrays of humming birds are in the area and serve as pollinators as well. Indeed many flower shapes are such that they fit the long bill of hummingbirds.  We must have seen at least 10-15 different humming bird species all in one area of the cloud forest. They are very aggressive, territorial birds–little bantam fighters, with a heart rate in flight of about 1200 beats/minute (only small hearts can achieve this rate, because they reduce the distance over which the Purkinje system has to conduct to coordinate the contractile sequences of the heart, atrium to ventricle).

Environmental changes in cloud forests from global climate change have already been documented in the cloud forests of Peru, where a drier climate change has been measured directly. The exaggerated seasonal changes in temperature and humidity have directly impacted on the positioning of plants within the cloud forest. Ecologists in Costa Rica are very worried that an excessive drying cycle may be taking place in the cloud forests of Monteverde and speculation is that such changes were responsible for the dissappearance of the Golden Toad, although this action might have been achieved through an indirect effect (see below).

Seasonal changes shape the ecology of the region and one of the most important cycles relates to fruit production from the many trees in the forest, the most important of which may be the Avocado tree, of which there are numerous species. To the casual eye, the differences between the two forests on either side of the continental divide seem trivial. But closer examination of the flora and fauna indicates that while there are many species common to both areas, unique species of plant and animal life can be found in one region but not the other. The difference in the moisture delivery system and temperature gradients have produced a truly remarkable gradient of plant and animal differences in ways that investigators are still trying to understand. Hundreds of different species of birds, mammals, amphibians, butterflies, snakes and hordes of invertebrates can be found living in the region. Other animals such as jaguars and wild pigs (peccaries) have all but disappeared in the Monteverde forests due to habitat degradation. The Monteverde region is a paradise for bird watchers (I showed a few guides and hiking companions the great advantages of image-stabilized binoculars for viewing long distance objects, which provides much greater image clarity through elimination of user vibration–don’t go home without one). You can’t make out the features of a monkey in the trees without an image stabilized viewing system.

Three-wattled Bellbird

An educational film we saw about the ecology of the Monteverde region, while visiting the area for several days, pointed out some of the essential characteristics of the rain and cloud forests across the divide and how the overall ecology of the cloud forest was heavily dependent on the migratory pattern of a single bird–the Three-wattled Bellbird. This bird feeds almost exclusively on Avocado fruit as it comes in season (not the big ones you see in stores, but much smaller fruit about the size of your thumb). The male Bellbird has a very loud, almost screeching sound that falls short of a songbird call, but it is one of the loudest sounds in the forest and very unmistakable. You can listen to it here. The Three-wattled Bellbird has a lowland-highland migratory pattern that is essential to the forest ecology because the Avocado seeds eaten by the bird are not digested, but are distributed  through the feces to serve as a continuous source of new growth for the forest. Apparently, without this single bird, the cloud forests would lack a widespread mechanism for regeneration. There is evidence that these birds are rapidly being depleted in many forests in Costa Rica. The trees in these forests get very large, with a mixture of giant Palm and Avocado. You cannot tell the age of the tree by looking at tree rings, as there are none. The continuous growth of trees in the tropical climate eliminates the more northern cycle of seasonal growth which produces tree rings that aid in dating of forests and trees.

The forests in Costa Rica support a truly remarkable variance in birds and other animals. It is one of the truly great centers for birding, though that is best done in December or January when new Avocado fruit sprouts in the mountains. In addition to the Three-wattled Bellbird, the fascinating Bare-necked Umbrellabird puts on quite a show and the Resplendant Quetzal is a major show stopper. The area is also rich in parrots, monkeys, tree sloths and serves as the migratory breeding center for hundreds of different butterflies and large numbers of small poisonous, but highly colorful frogs, about 1 inch in diameter. Some of these frogs live within the pedals of the tree bromeliads which capture and retain water. They seem completely protected, as their bright colors warn predators of their poisonous nature, so that they are eaten only at the peril of the predator. At night thousands of these frogs make the forest come alive with the chatter of this rich orchestra intent on trying to find good sex.

Yellow-Banded Dart Frog

Despite a strong commitment on the part of the government to maintain the region as a primitive forest ecosystem, land development, both private and public, continues at a rapid pace, so the long-term future of these forests remains a matter of speculation. It’s hard to know if the ecotourism that now supports a very expanded economy for the region is helping to preserve the forests or helping to accelerate their decline. On the one hand tourism leads to expansion of facilities, but on the other, it provides farmers with a more attractive alternative for preserving their land as part of the forest reserve rather than clearing it for farming. One of the best bird trips Rosemary and I experienced was when we went by ourselves in a private reserve area, where we had to pay a few Colognes to enter, but the birds were more numerous than those in the park reserve itself. But, if these special areas are lost, we are guaranteed to lose thousands of unique species who will join the plight of the Golden Toad.

It has been estimated that perhaps 1/3 of the global amphibian population is under ecological stress and that over 120 amphibians have become extinct since 1980. These numbers are alarming because in many cases, the extinction has taken place in areas that are protected, like the story of the Golden Toad in Costa Rica. The single most alarming study (Whitfield et al., PNAS 104, 8352, 2006) was reported a few years ago based on a thirty-five year observation within a biological field station in La Selva, Costa Rica, a protected, old-growth lowland forest. During that period, approximately 75% of the amphibian population has declined since 1970. The trend is similar for reptiles as well. The reasons cited in this study are not those of global climate change (seems to operate in some cloud forests and may be responsible for the loss of the Golden Toad), or the introduction of harmful microorganisms (which seems to operate in some areas), but instead appears to be the result of climate-driven loss of leaf litter, which serves as a critical microhabitat element for frog survival. When you consider that these areas are protected, imagine what must be happening in other regions, about which we know a lot less because we don’t have the appropriate longitudinal studies or the feet on the ground to make the relevant observations. Climate changes of course don’t do all lifeforms in,  but they do change the distribution and the numbers. Although it is much too early to say with certainty, it looks as though the awaiting winners of climate change are microorganisms, such as bacteria and fungi, which are ready to move in when some disturbance in the environment changes the dynamic balance and biodiversity of the region.

There are many scientists who believe we are living at the beginning, or perhaps even further along than that, in the sixth mass extinction period. The current one is every bit as dramatic or even more so than the one that eliminated the dinosaurs some 70 million years ago. That last mass extinction was probably caused by a massive asteroid that hit the earth near the Yucatan Peninsula. Everyone agrees that the current mass extinction is not the result of an asteroid, but is being caused by evolution’s supposedly greatest triumph–the human species. If so, how poetically ironic. Can the species that is causing the new mass extinction show its capacity to recognize and reverse its behavior or do we need another species in the future, perhaps evolving out of the current success to reverse the destructive environmental trends of the last few hundred years and learn how to better manage our small blue planet? Right now, the amphibians are showing signs of the first massive, known species decline and elimination. Because they reside in the tropic and temperate zones, the massive habitat destruction in these regions may well lead to elimination of amphibians, with animals such as the Golden Toad leading the way, like an early canary in the mine of habitat destruction. We have mislabeled what we are doing to the earth: it is not “Global Warming” but “Global Climate Change and Mass Species Extinction.“ The latter is a far more accurate description of what our actions are doing to this planet. Mother nature has started to talk back; more Katrina’s are on the way, simply because the water temperature elevations dictates that likelihood. Yet the very forces with which Nature speaks to us, such as more massive and extensive tropical storms, will also contribute further to species extinction. None of us alive today will know the answer to the riddle of whether evolution’s greatest success has been the planet’s greatest disaster.

With the current administration coming to an end, the one that was able to suppress science rather than help it flourish, we will see and hear more about these problems and since the forces that will produce climate change are already underway, we will go through a dramatic alteration in species preservation: that part is unavoidable and it has already happened on a massive scale. The question is how far are we willing to go and what can we do to stop it? Population control is obviously essential, but we are headed for a significant increase in population during this century which will only intensify habitat destruction. Yet, habitat destruction by itself is not the only problem. The main challenge is how adaptive we are in addressing these problems as they get identified. Have we as humans lost the Darwinian capacity to go through the process of natural selection to enhance our survival probability, responding to forces that germinate in our brains, by process that we don’t actually see, touch or feel in the ordinary sense? It is clearly a frontal lobe issue and hence, in part, a political issue as well. Who will be the survivors and what will they do to achieve success? Will it be economic? Will it be cleverness? So far, all we know from the global climate change models is that they underestimated the speed with which these changes would take place and that everything that we see happening that we don’t like, will get worse and do so more quickly. Deserts will grow, rainy areas will get more rain, hurricanes will be larger and more violent, ocean currents based on polar ice caps will decline or disappear and the polar ice caps themselves will melt. It should be easier to get a suntan, so perhaps the tanning salons will be stressed for their survival. So far, we don’t have much good news on this issue, except that Minnesota, the land of 10,000 lakes, will be able to offer one hell of a lot of beach-front property.

RFM