Archive for August 10th, 2010

We wake up early to the sound of our alarm to go bird watching with Ricardo. Our only friend on the nets is a moth. I head out with Greg and find Sarah already with Ricardo. We watch the Cecropia tree in front of the main cabin and find some birds. The first one we see is a Great Kiskadee, the largest flycatcher. It has a yellow breast and black eye stripe. Later, we find a Common Tody-Flycatcher, the smallest flycatcher here which has yellow underparts and a yellow eye. Our last flycatcher is a Streaked Flycatcher which has a ruddy tail, black beak, and a streaked brown breast. We also see a Yellow-crowned Euphonia, with its bright blue and yellow coloration. Several white Cattle Egrets fly overhead and a Roadside Hawk sits nobly by the…roadside.

Morning at TFI

The birdwatchers return for breakfast, after which we head out into the forest. Starting from the main house, we find a guava tree. It has brown, bare, shredded bark, which characterizes this tree which is usually found where old pastures used to be. We see a Blue Morpho flying erratically. For such a big, beautiful blue butterfly, it flies like it is drunk. Perhaps this is caused by its large size (it could fill up a small pan), or perhaps it fools predators. On our way to the primary succession forest (there used to be pasture there), we see a papaya tree, yucca, ornamental ginger, and a drasina. Ricardo points out mani, a legume ground cover, much like clover. We also see a Ceiba tree, whose spines and huge size do not disguise it at all. This is a fast growing tree whose compound leaves are now high above the canopy. In the temperate forests, nearly all later succession trees are shade tolerant. This is not true in the tropics. There are two main gap growing strategies: fast growing shade intolerant trees and slow growing shade tolerant trees. Nearby is a Cedro, a slow growing tree. Growth rate correlates inversely with wood quality. On this tree, we see a Golden-naped Woodpecker, which frequents the forest, unlike the Red-crowned Woodpecker, which prefers the open country.

Some tropical kudzu creeps along the ground. Fortunately, it is not nearly as aggressively invasive as the variety in North America. The kudzu points towards a fruit with a hard seed. This means that the plant is trying to have a mammal eat and disperse the seeds. It may have come from a Molina tree, which came from India. This is near a Ron-ron tree, which grows slowly, generating valuable wood. An eracea wraps around the trunk.


Walking up the trail, we see a heliconia, known for its colourful flowers and banana-like leaves with J-shaped vination. A calathiea has similar leaf shape, but has S shaped veins. Further, there is a piperacea, with jointed, knobly steps and candle-like inflourescence (flowers). Rubicacea is another plant that we see, and belongs with the coffee family. One can identify them by observing their opposite leaves.


Due to the wet ground and soil poor in nutrients, trees have buttresses and stilts. This includes some Habio, which have spikes and poisonous sap. The seed pods will also burst into shrapnel to disperse the seeds. This is one mean and well-defended tree.

Stilt Roots

Habio tree bark (note the spikes!)

Habio seed pod

Surprisingly, we see palms. This is a good sign, as they usually only grown in primary forest.  Ricardo points out a lechoso which can be distinguished by a vein surrounding the edge of the leaf and tops which lean over. Cutting the lechoso results in milky sap pouring from the stem.

Big Millipede

In the upper primary forest, we begin seeing poison dart frogs. They tend to congregate under stilted trees. At one point, we see a fantastic courtship ritual between two red and blue poison dart frogs. The male follows the female up the tree while puffing up his throat and peeping as loud as he can. I assume that in his mind, he is bellowing. Up further, we see a green and black poison dart frog. He is much larger than the red and green ones. Poison dart frog females chose their mates. The males then take the tadpoles to water, be it in a bromiliad, curled leaf, or puddle. The females will sometimes lay extra unfertilized eggs there as food for the tadpoles. The tadpoles will then develop. During this period, the larger green and black tadpoles will often eat the red and blue ones if they are in the same pool.

Red and Blue Poison Dart Frog

Male (lower) and female (higher) Red and Blue Poison Dart Frogs

Male Red and Blue Poison Dart Frog Serenading the Female

Near the top of the hill, we see a huge tree whose trunk must be nine feet in diameter. It has a large set of buttress roots. We sit for a break. We see a developing Titan Arum. Every few years, these plants bloom. The flowers smell like rotting meat, giving it its common moniker: the corpse flower. A Rufous Piha sounds in the distance. they are known as protectors of the forest because they make a distinctive call upon hearing a gunshot. Pihas are lek birds. A lek is a group of male birds which make oral or visual displays to attract females in order to reproduce. Males are only there for the act of copulation. Usually, the best spot in the lek is taken by an older bird with whom the females usually reproduce. Younger birds rarely mate, but they learn as apprentices who will eventually take over the best spot. Blue-capped manakins are also lek birds. The pihas, in comparison, have exploded leks. That means that the males are slightly separated, but in one general area. Lekking behavior only occurs when there is enough food for the female not to need help feeding the chick. Scientists believe that in an ecosystem like a tropical rainforest where there is high amounts of predation, having two parents could be a disadvantage, as it means that predators can spot one of two birds who are flying to the nest twice as often. Thus, it may be to the chicks’ benefit to only have one parent.

Big tree (I have no clue as to the species. In a 100 meter square plot, there are more tree species in primary rainforest than in all of the US!)

Our discussion turns to forest structure. Here, the trees are taller than in temperate forests. The rainforest also have more vines due to the heat and more evapotranspiration. The heat, however, causes problems for bryophytes. Our TFI forest is somewhere between a wet and moist forest. It is not deciduous as moist and dry forests, but does not have enough epiphytes for a rain or wet forest. The talk is interrupted by my sighting of a Chestnut Mandibled Toucan. The tropical bird causes everyone except Ricardo, who seems a bit bored by it, to look around in the canopy. I try to point it out from behind its leafy hiding spot.

Chestnut-mandibled Toucan (sorry for the poor image quality; taken through binoculars)

When the toucan flies off, we return to our discussion. Branches on the trees do not appear until higher up on the trunk. The layers of trees are hard to distinguish. Here, the sun passes exactly 90 degrees overhead, resulting in equal distribution light. This causes there to be no distinct layers, but instead trees filling in almost every level of the canopy. In the temperate Northeast, the sun is concentrated at 20 and 80 feet, resulting in two distinct layers of forest canopy.

Complex rainforest structure

Decomposition is fast here and there is only a thin layer of organic matter and humus. Most of the nutrients are trapped in the vegetation. There is also a huge diversity in tree species. Unlike the cloud forest, they can be pollinated by more than the wind here, as there are numerous insect and bird species.

Upon our return, we eat lunch and get our projects. I hope to either be assigned to biomass census of trees or trail management. I am selected for the latter, along with Sarah and Brian.

At 3 pm. a torrential rain storm begins. Oddly, the more it rains, the more the humidity increases. After nearly four hours and four inches of rain, humidity rose from 60% to 98% The trail teams go out to dig water bars and culverts to divert the flow of water. This is a lesson in futility as we cannot prevent erosion, but we may save the road. We also build a rock dam to direct the flow of water down a hill into a nearby stream.

Rain causes the river to rise

We go out for a rain walk. The stream nearby our cabin which we wade and bath in is now a roaring torrent. It has probably risen three feet in a matter of hours. The pasture watershed for the stream is not efficient at infiltration, or absorbing water. A nearby forested area, which has an equally large watershed is still full of sediment, but it has not risen as much, as the forest is much better than the pasture at infiltration. Our swimming hole is overflowing. The rain is pouring down; clearly the little summer has not begun as of yet. The raindrops are fat and almost sting me as they fall from the heavens. I cannot wait to wear dry clothes. The Ticos gawk at us and probably mock our walk in the rain. Back at base, we get dry and warm up in bed as we fall asleep.


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