Steve Yanoviak, tropical biologist
Steve Yanoviak is a postdoctoral research associate at the Evergreen State College in Olympia, Wash., and he currently resides in Costa Rica nine months of the year, researching rain forest canopy insect diversity in the Monteverde cloud forest. He has been studying the ecology of tropical insects for over seven years.
Sunday, 27 Aug 2000
MONTEVERDE, Costa Rica
I have a habit of not working in the forest on Sundays, so I will take this time to tell you a little about my surroundings and what I am doing here in northwest Costa Rica.
I live in the “town” of Monteverde. It does not look like a stereotypical town in the U.S. by any means; there is no Wal-Mart, no traffic light, and the unpaved road is shared by cars, horses, motorcycles, ox-drawn carts, and tour buses. Most of the homes are nestled in the woods, and people visit their neighbors via a series of trails through the forest. This community was established by some pioneering Quakers around 50 years ago. They came here in search of a peaceful place to set up dairy farming operations and to live in harmony with the surrounding forest. The founding Quakers recognized the value of the watershed, and they protected that essential resource by creating the Monteverde Cloud Forest Reserve.
The Reserve is a huge tract of largely undisturbed cloud forest covering the top of the mountain (part of the Cordillera de Tilarán) from about 1,500 to 1,800 meters in elevation. The forest is incredibly lush, and harbors several charismatic species, including resplendent quetzals and big cats. Each year, about 50,000 tourists come here to walk the trails in the forest, and tourism drives the local economy. The forest is called a “cloud” forest because most of the moisture that feeds the plants comes in the form of wind-driven mist and fog. During most of the year, trade winds pick up moisture from the Atlantic and carry it westward across Costa Rica to the Pacific. The mountains in the Monteverde area force the winds to a higher altitude, and the lower pressure and temperature causes the moisture to condense into clouds. This effect is called “adiabatic cooling” and is critical to the persistence of the forest. The trees, and the many other plants living on trees, collectively act like a big sponge, extracting moisture as the clouds blow through. Recent studies by Dr. Alan Pounds indicate that global warming is causing the cloud bank to rise in altitude. The rising cloud bank means that less moisture hits the mountain, and this will obviously have negative effects on the native vegetation over the long term.
When you walk in the cloud forest, one of the first things you notice is the great abundance of epiphytes — plants that live on top of other plants. Bromeliads, orchids, and ferns are some common examples, and they are all abundant (along with mosses and even some woody plants) on the branches and trunks of trees in the Reserve. My colleague, Dr. Nalini Nadkarni, has been studying the ecology of epiphytes in this forest for nearly 20 years. To mimic the effect of a rising cloud bank on these plants, Nalini moved some of them from the Reserve to lower elevations where there is less moisture. Not surprisingly, most of the transplanted epiphytes died in the drier environment. This result suggests that global warming will gradually, but dramatically, reduce the abundance and diversity of epiphytes in this and other forests.
I am working here with Nalini to document the insects and other invertebrates that live in association with epiphytes. Specifically, we want to know if epiphytes in old, undisturbed forests (400+ years in age) contain more invertebrate species than epiphytes in young (40-year-old) forests that were once pastures. To do this, I climb trees in each forest type and collect small quantities of epiphytes. Each epiphyte clump is then carried to the lab, where I use a special apparatus called a Tullgren funnel to extract the animals. Most of the critters that come out of the plants are very small — mites and tiny insects only a millimeter or two in length — so my assistants and I must then spend many hours counting and sorting the specimens under a microscope. (To see images of some of the amazing mites we find, check out this site.)
Tropical forests are packed with interesting plants and animals, and I will certainly tell you more about what I see, hear, feel (and maybe even smell) in the forest over the next several days. But I also see a lot of wonderful things in my house and yard …
I live in a small house in a Monteverde neighborhood called Bajo del Tigre. This is rugged country, and like most houses in the area, mine is precariously perched on a cliff above the Guacimal River. I awoke at 5:30 this morning to diffuse light pouring in the window of my loft and the sound of black-breasted wood-quail calling in the adjacent forest. Their call is surprisingly similar to a car alarm. I also heard the calls of brown jays and keel-billed toucans coming from trees near the house. The call of a keel-billed toucan sounds more like a frog than a bird. To me, it sounds like someone running their thumb along the teeth of a huge plastic comb, like the ones we used to get at the fair when I was a kid. (I’ll never understand what motivated people to make those useless things!) I glanced out the window just in time to see three toucans fly across the ravine behind my house. These are crow-sized birds, mostly black with a red butt and conspicuous multi-colored bill — obvious inspiration for Toucan Sam of Fruit Loops cereal. I never get tired of seeing them. A friend once noted that a flying toucan resembles a bird pushing a banana through the sky. This is perhaps the most accurate description I have ever heard. Toucans flap their wings vigorously for a few seconds to gain altitude, then their bill pulls them downward as they glide for a few seconds, and the cycle is repeated again and again.
After a breakfast of fresh local eggs fried in Monteverde butter and coffee that is processed just down the road, I sat on my couch to read. Much to my surprise, a scorpion fell from the ceiling and nearly landed on my open book. Scorpions are very common here, and I typically shoo two or three out of my house every day during the dry season months. I looked up to see what caused this particular one to fall (scorpions are pretty good climbers), and I was shocked to see that the wall behind me was literally covered with swarming army ants. Organized chaos is perhaps the best way to describe such a raid. Thousands of dark brown worker ants, each about a centimeter long and some with long, sickle-shaped mandibles, fanned out up the wall as another group spread across the floor. They left no space unexplored, and a great variety of cockroaches, beetles, and more scorpions fled from the cracks in my floor to escape their advance. Most efforts to flee were successful, but at least two scorpions were stung to death, dismembered, and carted away in pieces by remarkably organized groups of ants. The swarm raid passed after about 30 minutes, leaving behind a dense column of ants 10 cm wide that stretched across my porch and into the underbrush. Whole insects and a variety of insect parts seemed to float along a river of ants that disappeared several meters away in the forest. I spent hours watching them (from a respectful distance), and this was by far the highlight of my day.
will go into the forest and up a tree.