Wrestling With Vitreous Forms   6 comments

Felipe del Bosque Blog March 6th 2011

Darkening Skies – An Unfulfilled Promise

Earlier this week, on two successive days, the clouds gathered overhead and the sky darkened as an eerie portend of things to come.  It looked like we were about to be hit by a deluge.  If that had happened no-one would have shed any tears, any rain in the dry season is a most welcome relief from the hot and dry conditions that have prevailed for three months now.  We did get a small amount of rain for two consecutive days, but despite the promise of the ominously black clouds, the precipitation amounted to almost nothing, certainly not enough to make a difference.

So high daily temperatures continue and the forest floors have become more parched and cracked.  The late start to the dry season and the amount of rain we received during last year’s sodden wet season have proven sufficient to keep the Bosque creek running quite well.  The gardens still need the sprinklers though for a couple hours every evening following sunset.

Monkey Business

It has been business as usual with the mammals this week.  The monkeys are everywhere in the trees.  The Milky Trees, (Brosimum utile), are fruiting and that has been attracting the attention of the Spider Monkeys.  The fruit of the Milky Trees is known as breadnut.  It has a soft fleshy skin which the monkeys relish and a hard chestnut-like seed inside which they don’t.  If you are standing under one of the Milky Trees while the monkeys are feeding, there is a chance that you will be bombarded, not deliberately, by a rain of discarded hard seeds which do hurt if they hit you.

On several occasions, I had troupes of four monkey species; Howlers, Spiders, Capuchins and Squirrel, all passing by at once on the Zapatero Trail.  As ever the monkeys were accompanied in close attendance by the ubiquitous White Hawk.

The coatis and agoutis can be seen on a daily basis in the gardens and on the forest trails.  After all the excitement of the Puma sightings over the past month, this week resulted in only one sighting and that by the employees near the workshop.  The workers at Bosque, despite having lived on the Osa Peninsula all of their lives, for the most part have never seen a wildcat, and so their excitement is every bit as tangible as those guests who are lucky enough to see one.

Almost every night as I return for my nocturnal lucubration I happen across a Nine-banded Armadillo, the presence of which is consistently revealed by its resemblance to a tank being driven through the forest.

Another mammal seen almost nightly is the unpleasant looking Virginia Opossum.  I watched one the other night displaying typical breeding season scent marking behavior as it rubbed the side of its head back and forth on the lower part of a tree.

Bringing the House Down

One night last week as I was working late in the office, I heard a noise from outside the office window that sounded like someone systematically dismantling the thatched roof.  When I went to investigate, I was confronted by a Tamandua, an anteater, hanging from the beams only 6 feet from the ground.  Tamanduas are related to sloths and armadillos and following the cerebrally vacant pattern of their dull witted cousins, they do not seem to have an incredible amount of awareness of what is going on around them.  I stood right next to the Tamandua which was only dimly aware that there was something in front of it. Its long snout thrust out in front, noisily sniffing the air then came into contact with my out held hand.  At this point it thought it might be wise to retreat.

Tamanduas are not to be trifled with though.  They have very powerful front legs and long sharp claws that rip through dead wood as they search for their favorite prey, termites, not as one might imagine, ants.  Woe betide any creature unfortunate enough to consider this dullard of a creature as easy meat, those claws can inflict some serious damage.

Not So Funny For The Snakes

One notable feature for this week has been the apparent sudden appearance of the Laughing Falcons, (Herpetotheres cachinnans), which have been loudly announcing their presence.  They are medium sized cream colored birds with dark wings and have a distinctive broad black mask running through the eyes giving them the appearance of a villainous cartoon thief.  But at the moment it is their characteristic call which is revealing their whereabouts.  The Laughing Falcon is named after its call, that seemingly never ending series of slow “Hee Haw, Hee Haws”.

Laughing Falcons are specialist reptile feeders and they are particularly fond of snakes.  The bird’s Latin name, Herpetotheres cachinnans loosely translates into “Reptile destroying chortler”.

Clash Of The Titans

One night last week there was a little rain which brought about the following night an increase in amphibian numbers, namely one amphibian the Smoky Jungle Frog.  Always present around the pond, in greater or lesser numbers, the temporarily higher humidity resulted in five large males entering the water.  Like massively built Sumo Wrestlers, two exceptionally large males were doing battle, physically attempting to assert their authority over the domain of the breeding pool.  The slightly larger of the two heavyweights continually pushed his adversary beneath the water surface while almost swallowing whole the opponents head.

Little Things Matter Too

The daily hot, dry weather ensures that the butterfly figures remain high.  Just a brief walk around the perimeter of the Tropical Garden will reward the visitor with phenomenal numbers of butterflies from a myriad of species.

The two damp nights encouraged the Halloween Crabs to abandon their holes in the ground and emerge to forage enmasse.  Halloween Crabs are detritus feeding land crabs, about 2 inches across, with a bright purple shell bearing two orange spots which gives them the appearance of a Halloween mask.

Philip is a biologist, writer and photographer as well as the onsite naturalist guide at Bosque del Cabo Rainforest lodge on the Osa Peninsula, Costa Rica.


Photo Feature

While I was out on tour with a group of people this week, one lady noticed a beautiful 4 foot Terciopelo, (Bothrops asper), somewhat off the trail lying motionless amongst the leaf litter.  The snake lay there for a good few days only shifting position slightly.  With every new group that passed I would point the snake out, but for most people the cryptically camouflaged snake blended in too well with the dead leaves that very few people could see it until I pointed it out with a long stick.

Terciopelos are ambush predator pit vipers that lie in wait for unsuspecting rodents to pass by.  They sit off the trails amongst the dry, brown fallen leaves and unless you have finely honed spotting skills you will probably never see them.

Not too far along the same trail on the same day, as I was talking about a fallen tree, I noticed a little frog tucked up on top of a leaf.  It was a little Emerald Glass Frog, (Espadarana prosoblepon).  I am not sure how it managed to find itself so far from water and out during the day, but there it was.  After the tour, I returned with my camera to get some photographs.

Espadarana prosoblepon

Most Glass Frogs are a shade of green on the dorsal surface; it is only when you view the ventral surface that their name makes sense.  The skin of the underside is transparent and you can see the frog’s internal organs, the degree of transparency, the color of the membrane coating the viscera and color of the bones all provided useful diagnostic features for identifying the frog to species level.

Espadarana prosoblepon

The Emerald Glass Frog has a white sac covering the internal organs, which in some other species are very conspicuous, the heart and the intestines.  The bones of the Emerald Glass Frog are also green, a condition brought about by a bile pigment called biliverdin.  This is the same pigment that will cause a bruise you might get to initially look green before turning yellowish, bilirubin.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Temperature and Rainfall

Average Daily Temp High 94°F.  Average Daily Temp Low 73°F.

Average Daily Rainfall 0.02 ins.  Total Weekly Rainfall 0.17 ins

Average Daily Temp High 34.1 °C.  Average Daily Temp Low 22.5 °C.

Average Daily Rainfall 0.7 mm.  Total Weekly Rainfall 4.7 mm

Species List for the Week


  • Howler Monkey
  • Spider Monkey
  • Capuchin Monkey
  • Central American Squirrel Monkey
  • Northern Tamandua
  • Central American Wooly Opossum
  • Virginia Opossum
  • White- nosed Coati
  • Jamaican Fruit-eating Bats
  • Tome’s Spiny Rat
  • Agouti
  • Puma
  • Collared Peccary


  • Red-lored Amazon
  • Scarlet Macaw
  • Great Currasow
  • Laughing Falcon
  • Mangrove Black Hawk
  • Roadside Hawk
  • Swallow-tailed Kite
  • Rufus Piha
  • Blue-crowned Motmot
  • Chestnut-backed Antbirds
  • Black-hooded Antshrike
  • Common Paureque
  • Crested Owl
  • Short-billed Pigeon
  • White-tipped Dove
  • Blue-crowned Manakin
  • Red-capped Manakin
  • Fiery-billed Aracari
  • Chestnut-mandibled Toucan
  • Grey-headed Tanager
  • Summer Tanager
  • Bright-rumped Atilla
  • Great Kiskadee
  • Riverside Wren
  • Great Tinamou
  • Black Vulture
  • Turkey Vulture


  • Basilisk
  • Barred Ameiva
  • Four-lined Ameiva
  • Central American Whiptail
  • Golfo Dulce Anolis
  • Clawless Gecko
  • Mediterranean House Gecko
  • Cat-eyed Snake
  • Litter Snake
  • Tropical Bird-eating Snake
  • Terciopelo


  • Marine Toad
  • Red-eyed Green Tree Frog
  • Smokey Jungle Frog
  • Milky Frog
  • Black and Green Poison Arrow Frog
  • Fitzinger’s Rain Frog
  • Glass Frog


  • Adelpha cytherea
  • Adelpha serpa
  • Agraulis vanillae
  • Anartia Fatima
  • Anartia jatrophae
  • Anthanassa ardys
  • Archaeoprepona demophon
  • Caligo eurilochus
  • Callimormus radiola
  • Cithaerias pireta
  • Colobura dirce
  • Consul fabius
  • Corticea corticea
  • Cupido comyntas
  • Dione juno
  • Dryas iulia
  • Eueides aliphera
  • Eueides lybia
  • Euptychia westwoodi
  • Eurema albula
  • Eurema daira
  • Glutophrissa Drusilla
  • Heliconius erato
  • Heliconius hecale
  • Heliconius ismenius
  • Heliconius sapho
  • Heraclides cresphontes
  • Hermeuptychia hermes
  • Junonia everete
  • Magneuptychia libye
  • Marpesia berania
  • Mechanitis polymnia
  • Morpho helenor
  • Morpho Menelaus
  • Panoquina ocula
  • Panoquina panoquinoides
  • Pareuptychia ocirrhoe
  • Parides erithalion
  • Perophthalma lassus
  • Philaethria dido
  • Phoebis agarithe
  • Phoebis argante
  • Phoebis sennae
  • Pierella helvina
  • Pompeius pompeius
  • Pyrgus oileus
  • Pyrisitia nise
  • Pyrrhogyra crameri
  • Pyrrhogyra otolais
  • Siproeta stelenes
  • Staphylus mazans
  • Temenis laothoe
  • Turesis basta
  • Urbanus proteus
  • Urbanus simplicius
  • Urbanus tanna
  • Vehilius stictomenes


  • Calabash flowering and fruiting
  • Monkey Comb Tree flowering and fruiting
  • Black Alligator Tree Fruiting
  • Garlic Tree Fruiting
  • Candlestick Plant Flowering.
  • Cannonball Tree Flowering and Fruiting
  • Heisteria fruiting
  • Passion Vine Flowering
  • Rubber Tree Flowering and Fruiting
  • Almendra Fruiting
  • Stinky Toe Fruiting
  • Guanacaste Tree Fruiting
  • Nutmeg Fruiting
  • Balsa Fruiting

6 responses to “Wrestling With Vitreous Forms

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  1. Very interesting again Philip. While I consider myself a “mammaler” first and foremost, I have a huge soft spot for frogs, so I love the emerald glass frog photos.

    I think the red-eyed tree frog that jumped on me during our first trip to BdC is what made me quite fond of these little critters. So, it is good to see that frogs are still common there.


  2. Thanks Alan. Over 11 years of taking out tours at Bosque del Cabo I don’t think I have encountered anyone who really doesn’t like frogs.


  3. Terrific captures of the emerald glass frog, Philip. Well done! What a great sighting. My son and I visited BdC a few weeks ago and can’t wait to return. What a special place.


  4. Philip did you not have your camera @ office to get pics of the tamandua??? Remember the first rule @ BDC??? ALWAYS HAVE CAMERA!!! Those could have been really good neat shots…


  5. Philip was the tamandua a little lost or was he trying to tell you something?


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