The Rainforest Awakens My Senses
My very first walk into a rainforest was on Barro Colorado Island (B.C.I.) [bci pier]. We took a ferry called "Jacana" [ferry] to get to the island from the Gamboa Resort [gamboa]. The island was formed when they dammed the Chagres River to supply water for the Panama Canal in the early 1900's. This flooding isolated the island from the mainland. So, if there were any populations of organisms with slight variations that happened to be living on the island at the time it was flooded, they have now been effectively isolated from others of their kind on the mainland. I thought of Darwin and his study of the finches on the Galapagos Islands as I carried my suitcase off the ferry for a 3-day stay on this amazing island. [bci sign] I wondered if I would be sitting in the same seat for dinner or staying in the same dorm room as E.O. Wilson, the famous animal behavior biologist who studied on B.C.I. Now, I was anxious to find out how much a "real" rainforest would resemble all that I had studied, learned, and taught about this incredible tropical biome.
The rainforest is even more lush and green than I had imagined. [nice shot] I see huge green leaves, 12 inches in diameter. [large leaves] The canopy is so thick that I cannot see the sky. Is it sunny or cloudy out? Wait, here's a little patch of sun [sun] that has made it through all of the leaves (the canopy) to the ground. On B.C.I., only about 1% of incoming sunlight makes it to the forest floor (Leigh 2002). The rest is captured by the leaves that extend as far up as you can see. Will a small plant manage to sprout [new leaf growth] and be able to grow with just a few minutes of passing sunlight each day? The paths are strewn with fallen leaves. [fran on steep path] [forest floor] I notice that most of the leaves are brown and starting to decay. Some look like delicate lace; only the ribs remain. It seems some organism found the rest of the leaf quite suitable as nourishment. In other parts of the rainforest, the fallen leaves seem to be much greener. I wonder if some animal or strong wind or something else could have caused these leaves to fall before they got old and brown.
There are so many types of lichens-some are white, some gray, some green, some are flat, some raised, but they all seem to be hard and dry. Up until now, I have seen only one or two types of lichens. There must be 20 different types that I have seen in the first 50 feet of our hike. Lichens are mutualistic living situations between an alga and a fungus, where both benefit from the relationship. I didn't expect to see so may lichens in the rainforest. I thought they thrived in harsher environments.
Wow, look at that vine. It has its leaves lying completely flat against the tree trunk. I know I should not touch anything, but I just have to try to lift a leaf of the vine to see how it is stuck so snugly to the tree trunk. To my amazement, the leaf lifts off quite easily. It seems the vine just grows its leaves curved concavely to fit the curvature of the tree trunk. [leaf vine plastered to trunk] What an ingenious way to protect your leaves from wind damage and perhaps predation damage by insects and other animals.
We have been hiking for several hours now and I have just realized that I have not seen a single piece of litter during this hike. This is such a welcome discovery. I'm glad that the research scientists who use this island care so much about it to keep it so pristine.
My skin is starting to get wet. It is not raining out, but it is hot and still and my body has started sweating. I stop to take a drink from my water bottle. As I do, I notice that I have not seen a single mosquito yet. By this time in N.J., they would have been swarming around me and feeding on me. Is it possible that the Americans under Dr. Gorgas really killed all the mosquitoes while building the Panama Canal? Now I feel the sweat dripping down my back and also down my forehead. It's time to put my bandana on. [ocelot trap] Notice how red my face is as I stand near a trap that catches ocelots so they can be radio-collared.
I am quite amazed that I do not hear any insects buzzing in my ears. Where are they all? I expected so many! There are so many sounds. I recognize a cicada by its loud buzz. But, there are so many other sounds-birds, frogs, insects, even mammals. That long, repeated shrill sound is a tinamou. We cannot see this bird, only hear it. My bird book shows that it looks somewhat like a chicken, so it could be on the ground as well as in the tree.
Wait, what is that loud, deep howling sound in the distance? I would have guessed it was hippotomi fighting. It is the sound of 2 troops of howler monkeys communicating. I can't believe that such small animals can make such a loud, deep sound! I hope we get the opportunity to see these monkeys before we leave B.C.I. in two days. Just 20 yards in front of us I hear the crack of branches being ripped off trees and crashing to the ground. We move in quietly to get our first look at white-faced Capuchin monkeys. How cool, I did not have to wait very long at all to see monkeys! They are beautiful, but my first thought is that they remind me of the monkey in the movie "Outbreak". The branches continue to fall around us. I think this is not an accident and the monkeys are fully aware that we are there.
Just in case the white-faced monkeys were not good enough for a first hike in the rainforest, how about these 3 howler monkeys that are almost directly overhead. They are bigger than I thought-with beautiful brown coats. Look carefully-that one must be the mother since she has a smaller one riding on her back. On closer inspection, it seems the third one is also a juvenile. He is allowed to stray about 1 meter from his mother before she chases after him and brings him back close to her.
I envisioned the rainforest as being quite flat. That was a huge misconception. During this entire hike, we have been going up and down cement stairs. [cement steps] As we ascend, we pass trees covered with vines. Some vines are thick, some are thin, some are straight, but most are curved. [vine art] [vines] [another vine] [more vines] [straight vines] They often wrap around the tree trunk like a beautiful spiral ribbon on a cylindrical gift package [curley cue vine]. Vines wrap around tree trunks and use them for support so the vines' leaves can reach that precious sunlight. But, if the vine is too aggressive and strangles the tree it's climbing on, the tree will die and fall and the vine's leaves will no longer get the sunlight they need. Vines hang down on both sides of the path, forming an archway like the one we walked through when we got married. [arch]
Look down-quickly and watch where you step. You need to step over the line of leaf-cutter ants carrying pieces of leaves that they have cut to bring home (the ants in this photo are carrying purple Dipteryx flowers rather than leaves) [leaf cutter ants with flowers]. The leaves these ants carry are 50 times larger than each ant. I don't know how they carry such huge pieces-keeping the pieces upright in the air (like the sail on a sailboat) the entire time [leaf cutters on tree trunk] . Here's one with a slightly smaller ant riding on top of the leaf. It's called a leaf-rider and its job is to protect the leaf so that a parasitic insect can't lay its eggs on the leaf. If the leaf-rider fails, the egg would be carried into the nest and get nurtured along with the baby ants. So the leaf-rider waves away the parasite, or picks the egg off the leaf.
Can you imagine carrying a leaf that's 50 times your size, and then add a "sentry" that's nearly your size and weight on top of that? You can see the size of leaf pieces the ants carry by observing the chunks that have been cut from the leaves in this photo [insect damage on leaves] . We pass a huge mound of brown material that stands about as high as my waist. The mound is covered with trails of marching leaf-cutter ants. This is their waste heap, [waste heap] where they meticulously climb up to the top of the heap to drop off waste from their nest. If my own children were ants, I know they would not climb all the way to the top of the heap; they'd drop it near the base of the heap! I'm glad I'm not a leaf-cutter worker ant. It seems like so much walking and so much work, carrying such a huge leaf or flower and then walking so far carrying the waste to the refuse heap.
I've been so busy following the leaf-cutter ants that I have not noticed that it seems to have gotten much darker as I look around. I check my watch and it's only 11:30 AM. I knew it couldn't be sunset time already.
The intensity of the sounds has really increased. Now, I can hear howler monkeys in the distance in several directions. The frogs seem louder, too [tree frog]. What is causing this sudden intensity in animal sounds?
Oh, I have the answer to the increased intensity of animal calls. It seems the animals were predicting the rain that I now feel coming down through the trees. I can't really tell how hard it's raining because I don't know how much rain gets trapped by the thick canopy of leaves above me [thick canopy]. Although I have carried my poncho, I will not put it on. The rain feels good and I think the plastic poncho would be very hot.
Following the rain, the rainforest smells have really become apparent. I'm sure the new odor that is quite strong is monkey scat. I look for it along the trail and I think I see evidence of it. It appears lighter brown than the surrounding soil. My hunch is confirmed when I almost step on a female dung beetle rolling a ball of monkey scat across the path. [dung beetle] This will make the perfect environment for her to lay her eggs so her young will have food when they hatch. I cannot believe all the things I've seen on videos are coming to life right before my eyes. The smell of the rainforest now is so much more intense than it was before the rain. I'm amazed at the difference. I do not smell any flowers, though.
After the rain, the forest floor has become quite slippery. Wet leaves cover the cinder block steps as we continue to ascend and descend into different parts of the rainforest. The huge leaves are beautiful with raindrops rolling off of them. We pass a black palm tree. Greg tells us to be careful NOT TO TOUCH the tree trunk. As we pass the tree, I see why! Those spikes break off in your skin and are really difficult to get out! [black palm spines] [black palm trunk] [looking up trunk]
The sun peeks back through the canopy and reflects off a beautiful spider web. [spider web] [spider] We come to a junction in the trails and we follow the metal sign [sign] that points "BACK TO LAB". It is time for lunch. The cafeteria overlooks the B.C.I. pier [pier] and the Panama Canal [canal] . An agouti crosses the path about 5 meters in front of us. And I have still not seen a single piece of litter!
There is a white, cloudy juice out for lunch. It's nothing like I've ever seen before. I'm so thirsty that I give it a try. It's delicious. I have to ask several people before I find out what this wonderful taste is called. I've discovered a new taste sensation, at least for my taste buds, it's called soursop fruit. I will have to do some research to see what the fruit looks like! [fruit]
WHAT AN EXHILIRATING MORNING FOR ALL OF MY SENSES!
Pascack Valley HS
Leigh, E.G. Jr. Talk on the Ecology of Barro Colorado Island. July 25,2002.