Monteverde,  Costa Rica

Marietta College Biology and Environmental Science Department Field Trip 2005/2007

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View from the Continental Divide at the Monteverde Preserve - Looking east towards the Atlantic, much of what you see here is either part of the Monteverde Preserve or the Children's Eternal Rainforest.  Prevailing winds in the area come from the east, bringing moisture from the Caribbean, which falls as rain as the air moves higher (and thus cools) as it passes over the mountains.



Often called a cloud forest, there are several sub-types of forest at the Monteverde Preserve.  At the higher elevations; winds and other stresses stunt the growth of the plants there, and the resulting forest is often called an Elfin Forest.  The view above is from essentially the same place as the image at the top of the page; the upper image was taken on a clear day in 2007 and the lower one on a cloudy day in 2005.

This diagram shows how moist air from the Caribbean ends up as clouds over the mountains. Adiabatic cooling, whereby air cools about 10º C for every 1,000 m of altitude, means that Monteverde at 1,500 meters and higher is about 15º C cooler than it is at the beaches.




The key to the cloud forest is the moisture.  As mentioned earlier, warm, humid air coming from the Caribbean is forced up and over the mountains of central Costa Rica.  As it rises, the air cools and can no longer hold as much moisture.  This moisture largely falls as rain over the lowland rainforests of eastern Costa Rica, in places like La Selva and El Suerte.  As it moves through the mountaintops, the remaining moisture condenses into clouds, which may or may not shed moisture in the form of rain.  The cloud forests could thus be relatively dry places, however nature at this point steps in with extraordinary measures to remove the remaining moisture from the clouds.  Many of the plants and epiphytes in the rainforests have specialized surfaces onto which water condenses from the clouds.  The condensed water then drips to the forest floor, making the cloud forest a wet place even when it isn't actually raining.  The photos above and the one below right show the cloud forest living up to its name.  Note how the clouds actually move through the trees.  To the left, on a drier day you can still see clouds forming and intermittently touching the forests.   To the lower left and in the middle below you can see the adaptations used by plants to wrest the moisture from the air.  

In the image above left and the one below, you can see trichomes, or small hair-like projections emanating from the leaf of a rainforest plant (above) and the stem of an epiphytic vine (below).  As you can see, these projections form the nuclei for water to condense on; this water can then be used by the plant itself or the plant may allow the water to drip to the soil below where the roots can take it up.  The trichomes also solve another problem; they hold the water droplets off the leaf (or stem) surface proper, thus helping to prevent the growth of fungi on the plant surface.  




The elfin forest is located at the continental divide.  The image center above shows the eastern drainage; water in that area is flowing to the Caribbean Sea, while water behind the photographer flows to the Pacific.  The Pacific side of the divide is pictured immediately above (the Pacific is under the clouds in the distance).  Above right is the platform at the Ventana, or viewpoint, with the 2005 crew relaxing after a 2km hike up to the continental divide.  Looking out from the platform at the Pacific drainage, one notes two large landslides; note that these are in the preserve and are not the result of logging, construction, agriculture or other disturbance by humans.  It's useful to remind ourselves sometimes that not all erosion is caused by humans - it's shaped the landscape for billions of years (the Grand Canyon is not the result of a contractor using shoddy practices or a farmer failing to use contour plowing!).



Above: Testing the Continental Divide.

Below: The eastern slope.


One of the interesting features at Monteverde is a suspension bridge over a ravine.  Hardly as thrilling as a zip line, the bridge does have the advantage of allowing a leisurely perusal of the plant and animal life of the canopy, something one doesn't always get to see.  Above are two views of the bridge in the mist of the day we spent there in 2005.  

Not only was the day brighter on our visit in 2007, but it seemed to me that the forest itself was drier.  When I got back I compared images from the 2 trips, with some interesting results.  The two pictures to the right show the same tree trunk (albeit from different angles) on the two trips, and it is obvious that the plants are greener in the 2005 image.


Below are three images of a colorful flatworm we found on that tree in 2005 (I looked again in 2007 but it was gone).  Flatworms (Phylum Platyhelminthes) are divided into 3 classes, the members of two of which are parasitic.  Members of the third group include the free-living species such as the familiar lab animal Planaria.  Most of the free-living forms are found in aquatic habitats, but a few, such as this one, can live in moist habitats such as the cloud forest.


Flatworm Video

Video near the bridge.










Ferns are a big component of the cloud forest.  Above, the reproductive structures or sori are packed on the underside of the fern leaf.  Meiosis - cell division that reduces the chromosome number by 1/2 - takes place here to produce small, haploid spores (haploid means they have 1/2 the normal complement of chromosomes).  The tiny spores drift on the wind and settle to the forest floor, where they grow into small gametophytes.  These structures are also haploid, and produce both eggs and sperm.  In the moist rainforest, the fern sperm can easily swim to the eggs, which they fertilize.  The fertilized eggs then grow into diploid (having the normal number of chromosomes) fern plants, some of whose leaves will bear sori like the ones pictured and thus continue the cycle.  Seed plants replace the spore with a coated seed much more able to resist drought and tough environmental conditions, and the gametophyte is replaced by male and female multicellular structures.  The male structure in flowering plants is called a pollen grain; it can be spread by wind or animals and thus frees the plants from the need for liquid water for sperm to swim in.  Thus, flowering plants can occupy dryer habitats than ferns.

When new fern fronds grow,  they unfurl from tightly coiled "fiddleheads" like the one shown above right.

Coiled structures are not restricted to ferns.  This millipede has coiled itself up in a defensive posture.  The bright colors indicate a species protected by poisonous chemicals (or at least a mimic of such a species); the poison (sometimes a cyanide compound) is exuded along the sides.  When I first took these photos I assumed the tiny red "droplets" were the defensive chemical; closer examination proved them to be parasitic mites, getting a blood meal at the thin skin where the legs join the body.  Below center, a mating pair of millipedes.


Millipede Video



A relict from prehistoric days, tree ferns can be 30 feet high.  There are quite a few at Monteverde.  Flowering tree species such as conifers, palms and broadleaf trees have largely filled the niche of tall photosynthesizer in many of the worlds forests; but much of our modern coal came from forests with a much greater percentage of tree ferns.







Videos of the "feather flash"  One   Two


Just outside the gates of the preserve is the Hummingbird Gallery.  I've never been in the building, so I can't tell you what they sell, but outside they have a collection of hummingbird feeders that attract a stunning variety of hummers.  In most of the US we are lucky to see 1 species of hummingbird; in Costa Rica there are nearly 60 species.

Hummingbirds, of course, are small, active birds which can hover in front of flowers, all the better to use their long brush tongues to gather the flower's nectar for a quick sugar hit to keep the bird in the air.  They supplement this sugar fix with proteins gleaned from insects they hunt down.  A feeder with some red plastic to catch their eye and some sugar water to tank them up will bring the hummers in from miles around.

The Purple-throated Mountain-gem has a set of blue feathers on its head that it can "flash" to warn away intruders and competitors as shown in this video.

The Bananaquit is an unusual bird, somewhat related to warblers.  More generalized in its diet than a hummingbird, it feeds on plant juices from flowers and fruits, as well as on insects.

More Hummingbird Videos:

Fiery-throated Hummingbird

Hummingbird Dogfight







The Resplendent Quetzal is the "Holy Grail" for birders visiting Monteverde.  We caught glimpses of this bird, but as you can tell from the photo it was more of a "Not Entirely Repugnant Quetzal" 



The Cloud Forest, as mentioned above, is built on water and epiphytes.  These images show plenty of the latter; note the long trailing vines or lianas reaching from the canopy to the ground.

In this picture, a vine takes hold of a bigger plant and takes another step into the canopy.  Some vines grow from the ground up (this is common in temperate zones where harsh winters and dry conditions in the summer would kill canopy-top epiphytes without access to ground water); while others grow from the top down (such as the strangler figs).  This one is growing up.

Video: Rain in the cloudforest.





Not all the colors in the cloud forest are a shade of green.  Flowers and other organisms often stick out with bright reds and other colors.  Above, the Hot Lips "flower" really consists of two large bracts (bracts are modified leaves often found around flowers) surrounding the actual flower.  It is often pollinated by hummingbirds.

Planthoppers (left) feed on plant juices which they suck out of the plant with long, tube-like mouthparts.  Some may pick up defensive chemicals from the plant and have bright coloration.



I think the plant to the right is an orchid; orchids are a prominent group among the epiphytes.  Below, an inflorescence on the surface of a leaf. 



Snails and other molluscs would be expected to do well in the moist cloud forest habitat.  Above, a snail crawls across a leaf; to the right are some eggs, possibly from a snail or slug.


Two strange moths attracted to the light at the visitor center at Monteverde.  Moths, with their drab colors and "hairy" bodies, normally feed at night.  The hairs help hold in heat generated by the wing muscles. Butterflies, in contrast, warm themselves in the heat of the sun.  Male moths, such as the one below, often have elaborate antennae which are used to sense the pheromones produced by female moths (butterflies, by contrast, find their mates by sight at flowers during the day).  Caterpillars of both moths and butterflies feed on very specific host plants.



This large beetle was attracted to the lights at the Monteverde Visitor Center in 2005.  It was fascinating to watch, but I don't really have any ecological information to pass on; depending the species the larvae have dramatically different lifestyles.  

On the other hand, long-horned beetles (Cerambycidae) have fairly similar lifestyles.  The larvae usually bore through the wood of trees; the adults' purpose is to mate and lay eggs on new trees, thus dispersing the species.  We saw large cerambycids in the cloud forest both in 2005 and 2007.




The end of the road.  The road from Santa Elena ends at the visitor center at the Monteverde Preserve.  Tourists who have reached the mountaintop by renting a 4-wheel drive vehicle could drive and park here; most take taxis.  Cheaper still are the buses which run early in the morning, around noon, and in the afternoon to take people from Santa Elena to the preserve.



Below:  A map of the preserve and the paths we explored in 2005 and 2007.  Most of the preserve is in the Pacific drainage; however from the ventana at the lower right hand of the map one can see the forest on both sides of the divide.  I keep wanting to take the Sendero (trail) Chomogo through the center of the reserve, maybe next time.




Above:  A Google Earth view of the area from Santa Elena to Arenal, showing the relationships between these areas and the protected areas.    The red line roughly indicates where I think the continental divide is; the green line encloses major protected areas including the Monteverde preserve (actually a small chunk of the total, almost entirely to the west - left - of the red line near Santa Elena).  Other major reserves are the Zona Protectora de Arenal, the Parque Nacional Arenal, Zona Protectora San Rámon and the Bosque Eterno de Los Niños (about 20,000 hectares).  Protection in these reserves varies.  The Monteverde Preserve - more formally the Reserva Biológica Bosque Nuboso Monteverde (the Monteverde Cloud Forest Reserve) - started as watershed land bought and preserved by the Quakers and later was expanded to over 10,000 hectares.  It is administered by the Centro Científico Tropical, a non-governmental organization.  The visitor center, below, has a restaurant, gift shop and dormitory.  




A higher elevation usually means fewer reptiles, and this seems to be the case at Monteverde.  On the other hand, we did have a couple of good finds; the two snakes thanks to sharp-eyed guides.  

The Spotted Woodsnake is at home in the cloud forest as its primary foods include worms and slugs, both of which do well in the moist habitat.  

An unidentified anole pauses along the cable for the suspension bridge in the photo above.

The Striped Palm Pit Viper (left, below) is a snake of moist uplands.  It spends most of its time in trees; Savage (2002) reports about 41 bites from this venomous snake annually, with no fatalities.  Its arboreal habits put it at the ideal height to strike at humans moving through the forest.


Recycling in the cloud forest:  The dung beetles, above, have collected a small ball of (hopefully) monkey dung on a trail and are rolling it to a space where they will dig a pit and bury it.  Eggs laid on the dung will hatch into larvae that will feed on the undigested material in the dung - burying it protects the resource from other coprovores (dung-eaters).

Fungi (right) are among the few organisms with the enzymes necessary to break down cellulose, the tough material at the heart of wood and other plant materials (ironically, cellulose is composed of glucose, and should be an ideal food source, if it weren't so difficult to break down).  Fungi break down the dead trees in the forest and return the nutrients to the soil.  Fungi themselves may be important food for some organisms.  The part of the fungus that we see is the fruiting body; this part usually stands clear of the wood or soil so that it can drop tiny spores into the wind.  The spores will then alight on decaying material elsewhere.  The upper picture shows mushrooms, the lower one shows a shelf fungus.


This clearwing butterfly - a female no doubt - has landed on a leaf and is using its long proboscis to take up some bird guano.  The proboscis is normally used to gather nectar from flowers, but female butterflies also need proteins and salts in order to produce eggs, and those substances are abundant in the droppings - you can read more about it here; the butterfly pictured here is one of the  "ithomiine" butterflies mentioned in the article when it speaks of research done in Costa Rica.


Katydids - close relatives of grasshoppers - feed by chewing on leaves.  A wide variety exist, particularly in the forests of Costa Rica.  Katydids are most active at night; during the day they remain motionless in the foliage or in the leaf litter.  To avoid predation at these times, most katydids closely mimic leaves, and not just healthy green leaves but dead leaves or damaged ones (and, of course, katydid feeding will produce damaged leaves).  We saw these two katydids on our night hike; both resemble leaves which have been chewed on.  In both, the veins of the insect wings are arranged in a pattern similar to the veins in a leaf, complete with a "midrib".  The upper specimen seems to be trying the "damaged leaf" motif; the lower one resembles a fallen leaf and no doubt that species spends its daytime on the ground.



These katydids were seen at La Selva in 2005.

This caterpillar seems nice enough; one could almost imagine stroking its furry back.  That would probably be a mistake; many such caterpillars posses urticating spines.  These little spines can penetrate your skin, complete with toxins and allergens  A brush against one of these can lead to a rash for days afterwards.  The red "eyes" aren't eyes at all, just the hard head capsule enclosing the truly large jaw muscles that caterpillars use to chew their way through their plant food.


A feared inhabitant of the tropical world is the much maligned tarantula.   Yes, these are large spiders, and yes, like all spiders they possess a poisonous bite.  However. this species is not as fearsome - at least to people -as its reputation would have us think.  These tarantulas live in holes in the forest floor, and venture out only at night.  They feed mostly on invertebrates and small vertebrates.  Like the caterpillar above, these spiders possess urticating hairs; however they have one additional trick - they can fling these stinging hairs with their hind legs!  As for the fearsome part, how afraid can you be of an animal that any toddler could crush with one well-placed (and hopefully well-shod) foot?  

Passalid Beetles - also called "bessbugs" feed as larvae in decaying wood.





At the visitor center, this artisan was making incredible reproductions of forest creatures including frogs, scorpions, butterflies and hummingbirds.  I noticed he kept a copy of several of the laminated field guides handy, no doubt to improve the realism of his creations, some of which can be ID'd to species.

Glass-Making Video

Below: Lunch in the cafeteria.




Many of the insects came out only at night.  We went on night hikes both years to see them - and whatever else might be about.  One of the big advantages of these night hikes at Monteverde is that they are always guided, and the guides see (or at least know where to look) for a lot of things.  

This was our year for walkingsticks, and even the guide was amazed at the number we saw on the hike.  Many were mating; note that the males are usually smaller and slighter than the females, whose bodies must accommodate the much bulkier eggs).  In the picture to the left a male approaches a female walkingstick; below another pair is copulating.

Many walkingsticks are slender and twig-like; others are stockier.  We saw several of this latter form; note that the body is sculpted and colored to resemble lichen-covered tree bark - definite camouflage in an epiphyte-rich cloud forest.


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