Las Cruces, pt. 6: Rio Java/Cafe Mocha

After our first rest day, we were right back into the swing of things, and were busy again with lots of schoolwork. We spent Tuesday morning out in the field with our professor Susan, learning how to identify nineteen plant families. Later that day, we had a lecture from our other professor, Erika, on her research. She studies the mating system of Heliconius butterflies, which is unique because the male butterflies compete so fiercely for mates that they sit on the pupae of developing females so that they can mate as soon as (or sometimes even before) the female emerges as an adult. She told us about several interesting experiments that she's done, which are particularly cool because they seem to demonstrate opposite selection on two traits, body length and wing size, that are correlated with each other, so the selection effectively cancels itself out (although this family of butterflies also seems to have evolved a different body size ratio than other closely related families as a result). 

On Wednesday, we started the day with another hike out on the Rio Java trail, where we went for our first observations, and then accidentally when trying to find the waterfall on our rest day. We hiked out farther than before this time and dispersed ourselves along the trail to do another observational exercise. Instead of just soaking in the incredible surroundings, this time we were assigned to describe as many plants as we could in our field notebooks. We had about 30 minutes, which feels surprisingly short when you are trying to notice and record as many details as you can about a plant you've never seen (or at least paid such close attention to) before.

One of the plants I tried to describe had weird bumps on the leaves, which I think were caused by some sort of insect.

 After finishing up our observations, we began to head back to the station. I was near the back because Tessa and I were trying to practice identifying the plant families we'd learned the day before. With help from our TA, Daniel, we started to get the hang of recognizing the key traits of each family.

A large strangler fig (family Moraceae; above) and some cool vines (below) on the trail.

By hanging towards the back of the group and taking our time, we also got to see some cool and unexpected wildlife. First we saw a tarantula, which we thought was dead because it wasn't moving at all. After we spent a few minutes poking at it, we realized that it was actually alive after all! Then it decided to pose so we could all take pictures.

The tarantula was surprisingly cooperative!

Shortly after encountering the tarantula, we passed a huge strangler fig (similar to the one in the photo above). On the hike in I had noticed that there was an unusual and unpleasant smell near the tree, but I wasn't sure why. Our TA came in handy again and told us that it was the smell of... bat feces! Strangler figs start out their life cycle as vines that climb up the trunks of existing trees, eventually reaching the canopy and putting out leaves. With time the vines can outcompete the host tree for light and nutrients, causing it to die. When the host tree rots, the strangler fig is left like a hollow shell and continues to live independently. The strangler fig we saw was almost entirely hollow, and there were dozens of bats living inside! We pulled out a flashlight, stuck our heads into the tree, and looked up, only to see lots of bats hanging upside-down above our heads. After a few minutes of examination the bats started to wake up and move around, so we left. Unfortunately I couldn't get a good picture because it was too dark. Our last interesting sighting of the day was a lizard, which was pretty well camouflaged but I managed to get a decent picture of anyway!

That afternoon we had a lecture on Costa Rican geology, and how topography dictates the climate and weather patterns that allow for such a diversity of ecosystems in the country. Later we watched a short documentary about coffee production in Central and South America, which had economic and anthropological themes in addition to ecological information. Point of story: most of the time, farmers get screwed because of market fluctuations and the time delay before they can alter their crops in response to changing prices, and buying fair trade coffee is really the only way you can assure that the money you're spending is reaching the hands of the people who deserve it. While the concepts weren't necessarily new, it was interesting to get a more detailed look into the processes of coffee cultivation, processing, and sale.

Our last activity of the day was a lecture about forest fragments, to prepare for a field trip on Thursday morning!