Spider Monkeys y Heliconiaceae: Life at Las Alturas

Photo Credits: Hayley Stutzman

8:00 am on a Wednesday morning found 8 students, 2 professors, a TA, and a driver squeezed into a van, bumping along the road away from Las Cruces Biological Station. We spent the first part of the ride watching out the window and playing various car games from both the US and Costa Rica. When the paved road gave way to dirt and gravel we tried not to slide into each other and admired the driver’s skill at zooming along these steep, winding roads. There was a feeling of excitement in the car; we didn’t really know what to expect but it was a change from the normal routine and promised adventure.

            As we passed coffee fields and small, colorful houses we saw groups of people, from young children to adults, standing or sitting along the side of the road and watching us as we rumbled by. It made me feel like a foreigner. Mau told us they came to help pick coffee. When someone asked about child labor, he stated simply that the kids help their parents earn some extra money. I thought about how different their lives are from those of the 10 year olds at home, who spend their time at organized sports practices and summer camp.

            Up at the station, while we got a few introductions to the farm, Pablo, a visiting professor, gathered branches from surrounding trees and bushes and laid them on the porch. We knew the drill. We differentiated between simple and compound leaves, debated branching patterns, looked through magnifying glasses at little white dots in between the veins, and crushed the leaves to smell them. After Pablo had helped us determine the characteristics he would tell us the family. We had to ask him to repeat the names a couple times – Moraceae, Passifloraceae, Zingiberaceae. We saw plants in the fig family, the coffee family, and the palm family and tried to remember how to tell them apart.

            After pulling on rubber boots and filling up water bottles, we squeezed through a gap in the fence and tromped off into forest, Mau and Pablo in the front, Mario (our TA) in the back, and the 8 students in between. As we got further into the forest, the world around us changed. It got cooler and darker, the colors endless shades of green or brown, the occasional ray of sunlight highlighting a clump of leaves or patch of dirt. I couldn’t get enough of the forest and, as we walked, tried to simultaneously look at the canopy and between the trunks and still not trip over roots in the path. The amount of life in all directions was amazing, ants marching across the path, huge strangler figs towering over us, orchids, bromeliads, and vines clinging to branches, fungus growing on roots. A little while later we heard a sound like metal screeching on metal and stopped short. None of us had ever heard anything like it. Mau told us it was the bell bird-probably a juvenile practicing his call. We stood and listened to the unearthly sound for a few more minutes, craning our heads in search of the bird. The noise rang out even more in the otherwise quiet jungle, a welcome change from the constant buzz of cicadas we heard in the forests around Las Cruces. When we started walking again, the path began to slope upwards. I appreciated the plant identification stops as a chance to catch my breath. If we had already covered this particular family, Pablo pointed to a plant or passed out small clippings and had us guess the name. Sometimes we would figure it out with a couple hints and other times we would never get there and Pablo would explain what to look for next time. An uneven base on a leaf that looked like it came from a banana plant identified a Heliconiaceae. A leaf with a joint that helped it follow the sun was a Marantaceae, or a prayer plant.

We had just started walking again when a loud rustling came from the canopy up ahead. Wandering ahead cautiously, with Mao at the front scanning the trees, a few people caught sight of a monkey swinging through the branches. Soon we had caught up with the troupe and there were monkeys all around us, a mix of white-faced capuchins and the larger, almost red-colored spider monkeys. The capuchins quickly continued on their way, leaving the group of spider monkeys above us. We watched in fascination and amazement as they jumped from limb to limb, one with a baby riding on its back. They chirped and screeched, some sitting above us, shaking limbs, ripping them off and throwing them down at us. Mao told us they probably weren’t used to humans in their territory, that we were just another primate invading their space. While we watched them, we peppered Mao with other questions - what do they eat? How long do parents take care of children? Are the members of the group all related? I was thrilled at this opportunity to see truly wild monkeys in their natural habitat. Before coming to Costa Rica, I had only ever seen them in small cages. But even Pablo and Mao, who seemed to know everything about the forest, were excited because spider monkeys are both endangered and highly mobile. They move constantly to maintain a fresh supply of the fruits and leaves that they eat and we were just lucky enough to have our paths cross. Eventually, as the monkeys gave up on scaring us away and moved on themselves, we started up the path again, already feeling satisfied with the hike.

The trail continued steepening. Eventually we had to put away our field notebooks to make use of our hands as we scrambled over rocks and clung onto trees. The lush green forest gave way to a shorter, paler bamboo forest. Then, abruptly, we piled into a clearing that looked out over a valley towards the Talamanca Mountains and a huge national park that extends all the way to Panama. From our vantage point, all we could see was canopy, no roads or roofs or any sign of humans at all, just the green folds down below and the grey clouds floating above our heads. It struck me for the first time how rare such an experience was, to be surrounded by forest as far as the eye could see. In my experience, it has been special to even be out of earshot of a road. As I hike and enjoy the views and inspect plant venation and breathe the clean air, I feel incredibly lucky that these kinds of places still exist and even more so that I get to see them. And I worry that future generations won’t get the same opportunities. But that is why we are here, meeting inspirational people with similar concerns who are working to protect this wealth of beauty and biodiversity. As I perched myself on a rock and took out my lunch I also realized that, sometimes, it is enough to sit at the top of a mountain eating gallo pinto and soaking in the world around you.

Nicki Oppenheim, Washington University in St. Louis

The Art of Attentiveness

"Pay attention to your surroundings; there's always something going on and, if you're lucky, you can observe it."  This advice, offered to us by the Wilson Botanical Garden's resident naturalist on our first day at the Las Cruces Biological Station, has shaped my time in Costa Rica thus far.  This country is bursting with life, from the crowded avenues of San Jose to the subtler green mosaic of the forest.  In the United States, we are taught to turn our attention inward, but the most rewarding aspect of my time here has been learning to pay attention to what's around me.  

Our courses have been crucial to the development of our attentiveness.  The first two weeks of classes have involved lectures on insect and plant taxonomy and identification, the history of Costa Rica, and the sociopolitical aspects of coffee farming in the tropics.  Our first week here at Las Cruces, we went on a night hike to see what crawls and flies around the Wilson Botanical Garden under the cover of darkness.  The most attention-grabbing creature that we found was the tailless whip scorpion, a.k.a. the spider-like arachnid that Mad Eye Moody used to demonstrate the Unforgiveable Curses in the fourth Harry Potter movie.  Despite their fearsome appearance, whip scorpions are relatively harmless to humans and quite shy; we only found one after half an hour of searching, and even though we all shrank back from it, my instructor was able to simply pick one up and hold it.  

On other group hikes, our instructor has stopped us to point out the small wonders of the forest.  For instance, during one of our first hikes, he showed us marks in the dirt of the trail that are made by mountain lions.  It's still difficult for me to discern the difference between a cat mark and a footprint from the person in front of me, but I'm working toward being able to identify other signs of big cats, such as the odor they use to mark their territory.  Other points of interest during our hikes have included discussions of tropical flora, such as the strangler fig, which grows down from the boughs of its host and grows up to surround the unfortunate host, killing it not by strangulation, but by stealing all the nutrients and water from the soil; we have also stopped to observe birds such as the crested guan and insects like army ants.   As a result, when I walk through the forest surrounding Las Cruces, I have begun to take note of what's going on around me.  Instead of just looking at the forest and seeing a sea of green, I perceive epiphytes growing on a tree, or ants crawling on a bush.  I have enough background knowledge to question what these organisms' relationships are to one another--are they mutualistic partners, or is one gaining a benefit through commensalism while the other gains nothing? 

While my newfound attention to detail hasn't found me anything as impressive as the tailless whip scorpion on my own yet, simply paying attention has led me to smaller, but no less important discoveries, starting with the everyday experiences that I usually take for granted.  For example, an assignment to collect and identify insects transformed our common room here at Las Cruces into a menagerie.  Any and all insects that flew in our windows at night only to become trapped in the window, usually an object of mild revulsion or plain indifference, became a daily source of wonder.  We observed (and competed to catch) moths, katydids, and beetles.  My favorite common room discovery was when I walked into the room, fresh out of the shower, to find a beautiful member of the family Nymphalidae, about the size of my hand, sitting on the window which, with the help of a couple other students, I was able to catch and subsequently identify.

However, in my opinion, the most important insights I have gleaned are those into the connections between politics/policy and the environment.  This past week, we had the opportunity to visit a family-owned coffee plantation where the effects of international coffee prices and lack of government protection for coffee growers is evident.  Don Roberto, the owner of the cafetal we visited, is responsible for all aspects of growing and storing his coffee.  The roasted coffee beans that one buys at the grocery store are a world apart from the raw coffee bean.  Before processing, coffee beans are nestled inside cherry-like berries, making it necessary to wash and ferment the berries to degrade the organic material covering the bean.  In order to create the best-tasting product, Don Roberto and other coffee growers must ensure that the fermentation conditions are just right, otherwise they will lose some of their precious yield.  The beans are then dried and can be stored for up to several months.  When Don Roberto is ready to sell some of his product, he must shell the beans, which involves smashing them by hand in what is essentially a giant mortar and pestle.  The shelled beans are then sent to a roaster.  The bottom line is that coffee growing is a lot of work.  Yet, coffee is not all that Don Roberto grows.  In addition to coffee, he produces maize, yuca, cilantro, cinnamon, oranges, avocados, bananas, and plantains in addition to coffee to guarantee that he always has something to sell in case coffee prices fall.  The fact that Don Roberto and other small farmers are so vulnerable to shifts in coffee prices and ultimately must worry about whether their crop yields will put food on their table evidences the cutthroat nature of the coffee industry that favors the large corporations that monopolize coffee distribution over growers.  I am grateful for the opportunity to have met Don Roberto and his family, and to have had my eyes opened to the systemic inequality which disadvantages small farmers in Costa Rica.  I hope to continue to develop my attention to detail throughout the course of this semester so that I may see more of the interactions that govern both tropical ecosystems and tropical societies.

Emma Roszkowski, Grinnell College

A sheep in wolf's clothing: thoughts on mimicry in Las Cruces

 

            Without a doubt, symmetry and identicality are aesthetically stimulating. Clones, impersonations, and disguises figure prominently in plots of thrillers. But humans are not the only species that uses identicality to confuse and mislead others. Most people are familiar with mimicry, the evolutionary phenomenon by which two or more species resemble one another, often due to selective pressures from predators. Many people have heard the rhyme “Red next to yellow, kill a fellow; red next to black, friend of Jack”, to distinguish coral snakes from their less dangerous mimics, or have seen the owl-like eye spots that appear on the wings of many moth species.

            Shortly before arriving in Costa Rica, I had been talking with a friend about coral snakes and similar-looking species. It suddenly occurred to me that I only knew about visual examples of mimicry: insects that resemble sticks, milkweed butterflies that look like monarchs, cuckoos that sneak similar-looking eggs into nests of other species, and flowers that mimic bees to lure unsuspecting pollinators.

But many animals rely primarily on senses other than sight. Dogs, for example, have fewer color-sensitive cones than humans, but make up for it with their powerful ears and noses. A prey species evolving to fool a dog would do well to mimic another species’s sound or scent, not its appearance. And some animals use senses that humans don’t have at all. Is it possible that a species could evolve to mimic signals from magnetic fields to fool sea turtles, or thermal radiation signatures to hide from the infrared detection of snakes?

I was curious, but I didn’t have an answer yet. These thoughts were in the back of my mind as I arrived at Las Cruces Biological Station, the first field site I would visit in my semester abroad program with the Organization of Tropical Studies. In many of our early lectures and field outings, we discussed examples of visual mimicry—in such a biodiverse area as Costa Rica, it’s no surprise that many species evolve to resemble each other. In the Wilson Botanical Garden of Las Cruces, for example, I found passionfruit plants. Butterflies lay eggs on passionfruit leaves, which hatch into caterpillars that eat the leaves. As a defense against these butterflies, some passionfruit species produce egg-like spots on its leaves or tendrils, making it look like a butterfly has already laid eggs on this plant. Butterflies avoid plants that already have eggs, because their offspring would have to face resource competition—and possibly cannibalism—from the other caterpillars. I was still wondering whether mimicry occurs in other sensory modalities besides vision. During a class lecture on butterflies, I unexpectedly found an answer to my question.

Caterpillars of the genus Maculinea trick Myrmica ants by secreting pheromones that are chemically similar to those of Myrmica larvae. The ants take the caterpillar back to the nest and care for it, even at the expense of their own larvae, which often starve to death in the process. Once in the nest, the caterpillar also uses acoustic mimicry to mimic the sound of the queen, elevating its status in the nest. The well-fed caterpillar pupates, emerges as a butterfly, and flies out of the nest, enjoying the benefits of a free upbringing from the ants.

So it is true that non-visual mimicry exists to fool animals that communicate through other sensory modalities. Why had I only heard of visual mimicry before now? Given what I know about sensory perception in other species, I would guess that it is not because visual mimicry is that much more common, but rather because it is easier for humans to detect and study. In other words, there may be many other instances of mimicry, or other ecological phenomena, that are invisible or less apparent to us because of the way we perceive the world.

So what does that mean for me? I hope to become a biological researcher. I am used to thinking of scientific research as objective and impersonal. But scientific studies are motivated by questions, and questions stem from observations, and observations are limited by the blind spots of the observers. Learning about chemical mimicry in Maculinea and imagining how many other instances of mimicry we may be missing has reinforced my desire to incorporate fieldwork into my research career. It is important to me that I spend time with my study system, in order to break down my blind spots and understand the world that it experiences.

Reena Debray, Duke University