Mellow Yellow   4 comments

Felipe del Bosque Blog November 26th 2012

Coming to the End

This week the precipitation reduced and the sun hours increased dramatically.   In fact there were about four days without rain except for a smattering late in the afternoon.    It is too early to say whether we are in the dry season but if not then we are not so far off.

Why Change

It is difficult to better on a weekly basis that which had been seen the week before.  The diversity and abundance of both plant and animal life here at Bosque is so rich and accessible that unless something out of the ordinary happens or a set of climatic conditions change resulting in the stimulated response of some plant or animal group then most sightings are going to the same as the previous seven days.

The only new mammal sighting for the week was Alfaro’s Pygmy Squirrel, (Microsciurus alfari), which looks like a small dark colored chipmunk with a sparsely haired tail.  It is normally found in the forest and this week I saw them on several occasions.  The only other species of squirrel we find at Bosque is the Red-tailed Squirrel, (Sciurus granatensis).  These can be seen all around the grounds, quite often feeding on palm nuts or gnawing their way through the husks and shells of coconuts to get to the nutritious white flesh inside.

While out walking the trails, I saw three species of minute rain frogs on the forest floor this week: Stejneger’s Dirt Frog, (Craugastor stejnegerianus), the Rough-skinned Dirt Frog, (Craugastor rugosus) and (Craugastor crassidigitatus).  If you keep your eyes to the ground then every so often you should see movement down by your feet as these tiny amphibians leap out of the way of your footfall and hopefully to safety.


The Golfo Dulce Poison Arrow Frogs, (Phyllobates vitattus) can be heard, if not seen, calling from the creek beds.  The Black and Green Poison Arrow Frogs, (Dendrobates auratus), on the other hand can generally be seen most everywhere on the forest floor.

As the weather becomes progressively drier and the plants will begin to flower.  This in turn will bring out more insects including the butterflies.  It doesn’t take much, a few sunny days with no rain and out they come.  The species accumulation curves grow at an exponential before reaching a plateau later in the season.

Spiny Coats

The mucuna vines, (Mucuna urens), have been fruiting this week.  Their spiny coated seed pods can be seen hanging from slender tendrils that weave in and out of the branches at the top of the trees.  It is best not to handle these as those spines are tiny urticating hairs which embed into the skin and become almost impossible to remove while at the same time causing intense irritation.  The distinctive seed inside is known as the ojo de buey due to their resemblance to the eye of a bull.

Another flower blooming in the tropical garden is the flamboyant flame orange blossom of the African Tulip Tree, (Spathodea campanulata).  As its common name implies it originates in tropical Africa but is commonly planted as a non-native garden ornamental in Costa Rica.  Its other name Flame of the Forest is beautifully exemplified right now.

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

Yellow Peril

I had one group of people out with me one morning walking the zapatero trail on the primary forest tour.  Not so far into the tour and so only a couple of hundred feet down the trail I was talking about rainforest ecology when one of the guests pointed out something I had completely missed and walked straight by.  Lying coiled in the leaf litter at the side of the path was a deadly venomous pit viper, a Terciopelo, (Bothrops asper).

It coloration blended the snake, which was about 4 feet long, perfectly against the background.  The unusual thing about this snake was the very yellowy hue that it had as opposed to the normal mix of browns and grays.  Strangely enough this snake was sitting amongst some fallen dead leaves that were yellow in color, which may have been little more than a coincidence.  This meant that once the tour finished I would have to come back and get the photograph.

I returned after lunch and the snake was still lying exactly where it had been in the morning.  I set up the tripod and camera, selected the exposure I wanted and shot off a couple of photos.  I was using four flash units and all that light was too much for the poor reptile which proceeded to uncoil and slither away in the opposite direction from the bothersome creature firing bolts of light at it.  It moved off through the leaves and headed between a V at the base of a plant.  There it stopped.  I thought I had missed my opportunity but as it remained unmoving I thought I might be able to get on the downward slope and get some nice portrait shots of the snakes head looking directly up at it.

I folded the tripod and struggled through the undergrowth until I was facing the snake head on.  Very slowly and without making too much disturbance I managed to place the tripod so the camera was now positioned about six inches from the deadly venom delivering weaponry housed in the head of the snake.  I focused and “Poof” off went the flashes.  I was in deep shade and needed a lot of light.  The snake did not flinch.  I knew I was fairly safe as the body was in a straight line with no striking potential.  Another minor adjustment and I was now within just a few inches.  The snakes tongue flickered in and out, it knew I was there.  Those two pits on either side of the head between the eye and the nostril house very sensitive sensory apparatus that allow the snake to detect very small differences in background infra red radiation, it knew I was there alright.

I wasn’t concerned as I didn’t think the snake was showing any visibly obvious behavioral signs of being threatened.  Like many other things in life you get to know your subject through experience, although having said that it is sometimes complacency that gets you into trouble.  Still I managed to get the pictures I wanted and as soon as I had finished, the snake glided silently away down into the heavy cover of the vegetation on the forest floor.  It was another occasion where I felt privileged to have been so close up to one of evolutions most fabulous creations.

The Terciopelo is a pit viper of the subfamily Crotalinae which also includes the rattlesnakes.  They have a reputation as being very aggressive but as this individual demonstrated that is patently not true.  I do come across these snakes with a certain regularity and remove them to safety within the forest.  I can honestly say I have never had one act in an aggressive fashion towards me.

The problems occur due to their amazing crypsis or camouflage.  It is almost impossible to see them, even large ones on the forest floor amongst the leaf litter.  As was demonstrate by the individual above, you can stand right beside them and they won’t move, they won’t give themselves away.  They don’t bear you any malice, they can’t eat you and in a confrontation with something much bigger than themselves they will probably die.  So they lie stock still hoping you don’t see them.

Unfortunately they can be found in areas where people are working in the fields and if stepped on may retaliate to that form of provocation by biting.  Even then if bitten by a terciopelo it is quite often a dry bite, only 1 in every 7 or 8 bites results in a full envenomation.  So as long as you stick to the trails and don’t go wandering off through the undergrowth you should never see one let alone get bitten by one.  As for me I still feel that frisson of excitement when happening upon one and more especially if I get a close encounter such as this.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Temperature and Rainfall

Average Daily Rainfall 0.03 ins.  Total Weekly Rainfall 2.09 ins

Average Daily Rainfall 7.6 mm.  Total Weekly Rainfall 53.1 mm

Highest Daily Temp 87°F.  Lowest Daily Temp 74°F.

Highest Daily Temp 30.2°C.  Lowest Daily Temp 22.6°C.

Species List for the Week


  • Howler Monkey
  • Spider Monkey
  • White-faced Monkey
  • White-nosed Coati
  • Nine-banded Armadillo
  • Agouti
  • Alfaro’s Pygmy Squirrel
  • Red-tailed Squirrel


  • Mealy Amazon
  • Red-lored Amazon
  • Scarlet Macaw
  • Great Curassow
  • Black Hawk
  • Crested Caracara
  • Great Black Hawk
  • Roadside Hawk
  • Black-hooded Antshrike
  • Chestnut-backed Antbird
  • Wedge-billed Woodcreeper
  • Short-billed Pigeon
  • White-tipped Dove
  • Rufus Piha
  • Blue-crowned Motmot
  • Long-billed Hermit
  • Stripe-throated Hermit
  • Rufus-tailed Hummingbird
  • Blue-crowned Manakin
  • Red-capped Manakin
  • Chestnut-mandibled Toucan
  • Buff-rumped Warbler
  • Green Honeycreeper
  • Summer Tanager
  • White-shouldered Tanager
  • Bright-rumped Atilla
  • Dusky-capped Flycatcher
  • Golden-crowned Spadebill
  • Great Kiskadee
  • Great Tinamou
  • Masked Tityra
  • Black Vulture
  • Turkey Vulture


  • Cat-eyed Snake
  • Central American Smooth Gecko
  • Clawless Gecko
  • Common Anolis
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Litter Skink
  • Mediterranean House Gecko
  • Parrot Snake
  • Terciopelo


  • Banana Frog
  • Black and Green Poison Arrow Frog
  • Fitzinger’s Rain Frog
  • Golfo Dulce Poison Arrow Frog
  • Marine Toad
  • Masked Smilisca
  • Red-eyed Green Tree Frog
  • Rough-skinned Dirt Frog
  • Savage’s Thin-fingered Frog
  • Stejneger’s Rain Frog


  • Anartia Fatima
  • Dryas iulia
  • Eurema albula
  • Heliconius erato
  • Heliconius ismenius
  • Heliconius sapho
  • Hermeuptychia hermes
  • Magneuptychia libye
  • Mechanitis polymnia
  • Morpho helenor
  • Morpho Menelaus
  • Perophthalma lassus
  • Philaethria dido
  • Pierella helvina
  • Pierella luna
  • Pyrgus oileus
  • Pyristia nise
  • Theope publius
  • Urbanus simplicius


  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Apeiba tibourbou Flowering
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Bauhinia variegata Flowering
  • Cascabella thevetia Flowering and Fruiting
  • Citrus spp  Fruiting
  • Clusia rosea Flowering andFruiting
  • Clusia vallerii Flowering and Fruiting
  • Cocos nucifera Flowering andFruiting
  • Crestentia alata flowering and Fruiting
  • Costus speciosus Flowering
  • Couroupita guianensis Flowering and Fruiting
  • Dypsis lutescens Flowering and Fruiting
  • Etlingera elatior Flowering
  • Ficus insipida Fruiting
  • Heliconia chartacea Flowering
  • Heliconia latispatha Flowering
  • Heliconia pogonantha Flowering
  • Heliconia psittacorum Flowering
  • Heliconia rostrata Flowering
  • Hibiscus rosa-sinensis Flowering
  • Hymenaea coubaril Fruiting
  • Hymenocallis littoralis Flowering
  • Ixora coccinea Flowering
  • Lantana camara Flowering andFlowering
  • Lagerstroemia speciosa Fruiting
  • Morinda citrifolia Fruiting
  • Musa acuminate Flowering andFruiting
  • Nephelium lappaceum Fruiting
  • Piper auritum Flowering and Fruiting
  • Piper nigrum Fruiting
  • Piper umbellatum Flowering and Fruiting
  • Pleiostachya pruinosa Flowering
  • Plumeria rubra Flowering
  • Psychotria sp Fruiting
  • Spathodea campanulata Flowering
  • Stachytarpheta frantzii Flowering
  • Zammia sp Flowering




4 responses to “Mellow Yellow

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  1. I’m going to be very articulate in my reply. . . .FREAKING AMAZING!


  2. Awesome head shot of the terciopelo Philip! You’ve gut a whole lot more guts that I do. 10ft away with a 300mm lens is about as close I have been able to muster.


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