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Felipe del Bosque Blog June 10th 2013

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In Transition

This week has started the way the last week finished with relatively dry and bright conditions.  There had been enough rain over the previous few weeks to make sure that the ground remains moist but not saturated.  There has been a little overnight rain but the days have been cloudless and sunny.  Even though there has been some precipitation every night the creeks are still not running with water again.

Anole Who You Are

Bosque del Cabo is home to many different species of small lizards known familiarly to most people as Anoles.  They are not very large lizards ranging in size from 4 or 5 inches in length through to 9 inches.  They are arboreal insectivorous lizards and be found everywhere from ground level to the top of the canopy.  One species, the Golfo Dulce Anolis, (Norops polylepis), is so ubiquitous that it seems like just about every tree in the forest is home to at least 2 individuals.

Another fairly common species is the Pug-nosed Anole, (Norops capito).  It derives its name from the short snubby snout.  Despite its relative abundance it is not very commonly seen.  It is very cryptically colored, the rich greys, greens and brown ensure it blends in perfectly with the bark of the trees where it can be found, usually facing down with its head held away at almost 90° from the vertical.

Pug-nosed Anole

This individual was found on the Titi Trail while I was out looking for some forest birds to photograph, which is a departure from the norm for me.  As you can see it was in the perfectly assumed pose that I would have expected.  I photographed it from several different angles but despite my moving the tripod, albeit slowly, the lizard did not move, did not flinch once.  Subsequent inspection of the images revealed that only one part of its body had been in motion, the eye as it kept me under close scrutiny relying on its camouflage to escape detection but ready to jump and run off if its ruse was foiled.

Pug-nosed Anole.

This is the time of year when the eggs of Green Iguanas, (Iguana iguana), hatch and the young leave the nests.  Sometimes during the day the bright lime green juveniles can be seen lying on top of the low lying vegetation sunning themselves.  At night they can be found in the same locations but now sleeping.  While awake they are wary of an approaching photographer but at night they are dead to the world and make perfect, if somewhat subdued, subjects.  This one was above my head as I was trying to get photos of nocturnal spiders.  It did not flinch once as the flash went off.

Green Iguana

Marine Toads, (Chaunus marinus), abound at Bosque del Cabo.  Once the sun sets in the evening they seem to issue from every nook and cranny in huge numbers.  They are the largest of the Costa Rican amphibians, the females particularly getting to weigh in at 3 lbs at which they can attain the size of a dinner plate.  But where there are large ones there have to be small ones.  One of the paradoxes of the rain forest is that this the largest of the amphibians has possibly the smallest tadpoles.  When the newly metamorphosed tadpoles emerge from the water, and when they do so it is by the thousand, they are tiny, barely discernible, little black toadlets.  They then seemingly disappear and you rarely see an individual that is not then an adult toad.  This small juvenile I found on hopping across the forest floor.  The coloration is completely different from the adult form and could be so easily mistaken for a different species.  The adults tend to be uniform brown or a mix of brown and gray.  This one had blotches of green, brown, gray and a distinctive white stripe running down its back.

Marine Toad

It’s a Spider Man

Not long after sunset when the last rays of light fade in the quickly darkening sky that is when the nocturnal animals begin to emerge.  At first one or two Tink Frogs can be heard, their metallic clinking call will resonate through the background forest.  Progressively the chorus will be joined by a myriad of other calls, the males of different species joining the choral congregation, each one serenading as yet unseen females.  The females emerge later and select a potential partner for the evening, being enticed by a quality of his song that evades our selective range of hearing.

Bats will leave their roosts and head off into the darkness in search of food.  Depending upon species this could be nectar, fruit, insects, frogs, other bats, fish or blood.  Those with good hearing will detect the echolocation pulses of sound made by bats that operate at lower frequency levels.

Bats can be seen flying but a great many other mammals emerge and skulk in the shadows of this lightless world attempting to get through the night without being eaten or finding something to eat.  Cats, coatis, opossums and rodents are all very adept at moving around without you being aware of their presence.

Other calls will pervade the night air after sundown, those of the katydids and crickets that in combination form an insect white noise of hisses and clicks, the individual sounds of which are indiscernible to our ears.

But there is one other type of creature that now creeps out from its daytime hiding place the arachnids, spiders and scorpions.  These would come very low down on the list of people’s favorite animals but conversely very high on a list of the most feared and loathed.  If, after the dying embers of sunlight have faded and died, you stand long enough staring at a spot where a leaf has been cut leaving a hollow tube, you will see the horror unfold.

The first stirrings, the first movement will be the tip of a leg, a long, thin, hairy leg come into view.  It will be waving slowly from side to side, twitching, sensing the air to ensure the creature to whom the limb belongs is safe to crawl out from its daytime residence.  Another leg emerges then another and another.  Long and spindly covered with a dense matt of fine down interspersed with longer stiffer bristles.  A head appears bearing eight eyes.  Finally yet four more legs and the plump body are drawn out of that hollow tube and the beast with eight legs turns to settle facing down on the flat surface of the leaf.  This is a Wandering Spider, (Cupinnius spp).

Wandering Spider

Wandering Spiders are ambush predators, they don’t make a web although they will have a thread of silk attaching them to the substrate to aid in a quick escaped should they be attacked.  But it is the Wandering Spider, this highly adapted predator of the small world that surrounds us, that is normally the killer here.  Hold a flashlight by your eyes and shine it around in the darkness.  There you will catch the glint of a million and one diamond sparkles reflecting back at you in colors of orange, blue, green or white.  Even on the driest of nights the attractive miniature starbursts are there.  These are not droplets of water.  Follow the shine and there you will find yourself face to face with a spider.  Now look around, they are everywhere, in the bushes, on the trees and in the grass.  You are looking at eyeshine.

Wandering Spider.

The eyes of the Wandering Spider serve little purpose other than to differentiate between different light levels rather than resolving image.  Those hairs covering the whole of the spider’s body are sensitive to touch.  The bristles detect minute movements in the air currents surrounding the spider.  It now knows the direct location of its prey.  Small transverse slits, sensillae, on the legs are sensitive to minute vibrations so the movement of approaching predator or prey can be detected in advance of its arrival.

Prey, which can be anything from insects, small frogs or other spiders, is pounced upon, bitten and injected with immobilizing neurotoxic venom and digestive juices.  The prey dies and is digested within its own skin.  The spider then sucks out the pre-digested liquid soup.  There are no spiders in Costa Rica that are capable of killing a person but the Wandering Spiders have a bite that can cause some nasty ulceration.

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

Venturing Out

The grounds of Bosque del Cabo are a haven of biodiversity.  It is a miniature version of Corcovado National Park which covers a substantial area of the Osa Peninsula.  More or less everything you will see in Corcovado N.P. you will see here at Bosque with one or two exceptions.  The beauty of Bosque del Cabo is that it has such a rich variety of habitat with an excellent trail system and a 22 year history of non persecution of the wildlife.  Due to the large numbers of visitors who walk the trails running through the grounds of Bosque on an annual basis most of the animal life is not intimidate by your presence and can be approached to within a very close proximity without threat to you or it.  This has resulted in Bosque gaining a well deserved reputation as a wildlife aficionados or photographers dream location.

Open Osa

But as well as Bosque being a nice microcosm of all the National Park offers, the diversity of life continues off site too. I very rarely venture out of the grounds of Bosque.  I am surrounded by more than enough subject material to photograph.  Even if you do photograph the same subject, there are many different angles from which to capture the image as I means to which personality can be added or suggested by the way the creature is looking at you.  Most of my photography is macro composed largely of the small life found around the grounds particularly reptiles, amphibians and a great many arthropods.  My portfolio was drastically lacking mammals and birds, a situation I had decided to remedy over the coming months.

By way of good fortune, one of the Bosque guests who was staying over the course of the week was here more specifically to photograph birds.  One morning she requested a ride to the open areas several miles down the road to catch the birds just after sunrise.  I took the opportunity of jumping in the truck too and headed off to get some avian images.  The sun was well above the horizon when we arrived but the bird activity was intense.  Unfortunately there were a team of surveyors working in the river and so the egrets, ibises and herons had been scared off.  Conditions were very bright and sunny which was causing a lot of contrast so I decided to try and get the birds sitting on the wire fences that I could approach with the sun behind me.

The parrot family was well represented a little higher in the trees.  Scarlet Macaws, (Ara macao), were flying into their feeding spots in the fruiting trees.  The vibrant scarlet infused with rich blues and yellows of the noisy flying birds contrasted starkly with the background of green of the tree which hugged the base of the hills before giving way to open pasture in front.  Large numbers of Red-lored Amazons, (Amazona autumnalis), were flying in to feed at the same spots.  Smaller, stockier and with shorter wings than the macaws, the amazons made just as much or even more noise due to their greater numbers.  Typical of parrots the amazons are monogamous and can be seen flying in pairs but in this case there were many pairs.

By far the most numerous and noisy, especially considering their size, were the Orange-chinned Parakeets, (Brotogeris jugularis).  The trees were full of them screeching and squawking in a pitch higher than the other parrots present.  They were too high up in the tree tops to take a decent photograph until some commotion broke out and two landed above my head at about 7 feet.  They are vibrant green with a yellow belly, brown patches on the wings and as the descriptive name suggests a little orange under the bill.

Orange-chinned Parakeet

Parrots are seed eaters and the bill is adapted to extract the seed from the hard enclosed shell.  The bill is short, thick, hooked and very powerful which exerts a lot of pressure on a nut shell which once cracked allows the muscular tongue to remove the nutritious seed.

Another noisy bird sharing the branches at the top of the trees with the various parrot species were sizable numbers of Great-tailed Grackles, (Quiscalus mexicanus).  These are quite vocal birds and have a repertoire of calls, some more melodic than others but always more melodious than the parrots.

Great-tailed Grackle

The females are brown and fly in flocks.  The males are jet black with a bright yellow eye.  If a male should see a female close by he will puff up his feathers and let out a high pitched call.  The female will select her mate by choosing the largest males.

In a small tree by the side of the road there were a pair of Red-crowned Woodpeckers, (Melanerpes rubricapillus), tending to a youngster who look to be freshly fledged.  At one point the scraggly looking young bird flew down to a rotten fence post which it appeared to examine closely for some sign of insect life on which to feed.

Red-crowned Woodpecker

There were several other species of birds that were using the barbed wire strung between the fence posts as a vantage point on which to sit and wait.

One bird that is very common and can be seen sitting everywhere from the tops of trees to fences posts is the Tropical Kingbird, (Tyrannus melancholicus).  It is one of 384 species of Tyrant Flycatchers found in Costa Rica.  If you see the outline of a bird silhouetted against the skyline that continually leaves its perch sallying for flying insects you can generally expect it to be a TKB.

Tropical Kingbird

It has a fairly widespread distribution occurring from the southern United States, down through Central America into South America.  Once seen it is easily recognized by its gray head, yellow breast and long notched tail.

On any given day driving from Puerto Jimenez to Bosque del Cabo or visa versa at some point on the journey your vehicle will approach and cause to take to the air flocks of small doves that have been sitting in the road.  These are Ruddy Ground Doves, (Columbina talpacoti).  They are feeders on small seeds and inhabit open areas.  The back is a rich soft reddy brown with a gray head and shoulders in the male but the female tends to be a more gray brown.

Ruddy Ground Dove

Having been forced into taking to the air they don’t fly too far and usually settle on the fencing wires at the side of the road waiting for it to become clear again.  If you are on foot they can be quite approachable and that was the case with the female in this photograph.

There were two small birds sitting not too far apart on the fence posts that I managed to get photographs of.  They both sat quite still, not seeming to mind my presence.  One was a juvenile Mangrove Swallow, (Tachycineta albilinea).  Despite its young age it had already mastered the typical flight and would take off and skim across the upper level of the grass catching insects in its open bill then come and perch more or less in the same place for a while.  Being newly fledged it had not fully developed the albilinea or the white line above the eye that is so diagnostic of this species.

Mangrove Swallow

The other bird was a more subtly colored female White-collared Seedeater, (Sporophyla torqueola).  It is the only female seedeater with wing bars which makes identification slightly easier.  It just sat until I got too close and then off it flew.

White-collared Seedeater

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 0.11 ins.  Total Weekly Rainfall 0.80 ins

Average Daily Rainfall 2.9 mm.  Total Weekly Rainfall 20.3 mm

Highest Daily Temp 86°F.  Lowest Daily Temp 74°F.

Highest Daily Temp 29.9°C.  Lowest Daily Temp 23.6°C.

Species List for the Week


  • Howler Monkey
  • Spider Monkey
  • White-faced Monkey
  • Nine-banded Armadillo
  • Common Tent-making Bat
  • Western Red Bat
  • Red-tailed Squirrel
  • Underwood’s Pocket Gopher


  • Red-lored Amazon
  • Scarlet Macaw
  • Great Curassow
  • Crested Caracara
  • Pale-billed Woodpecker
  • Laughing Falcon
  • Yellow-headed Caracara
  • Cocoa Woodcreeper
  • Plain Xenops
  • Black-hooded Antshrike
  • Chestnut-backed Antbird
  • Short-billed Pigeon
  • White-tipped Dove
  • Stripe-throated Hermit
  • Red-capped Manakin
  • Chestnut-mandibled Toucan
  • Fiery-billed Aracari
  • Cherrie’s Tanager
  • Golden-hooded Tanager
  • White-throated Shrike Tanager
  • Golden-crowned Spadebill
  • Great Kiskadee
  • Great Tinamou
  • House Wren
  • Riverside Wren
  • Black-throated Trogon
  • Black Vulture
  • Turkey Vulture


  • Barred Ameiva
  • Barred Forest Racer
  • Cat-eyed Snake
  • Central American Smooth Gecko
  • Central American Whiptail
  • Clawless Gecko
  • Common Anolis
  • Common Basilisk
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Green Iguana
  • Litter Skink
  • Litter Snake
  • Mediterranean House Gecko
  • Terciopelo
  • Tropical Bird-eating Snake


  • Banana Frog
  • Black and Green Poison Arrow Frog
  • Golfo Dulce Poison Arrow Frog
  • Marine Toad
  • Masked Smilisca
  • Milky Frog
  • Red-eyed Green Tree Frog
  • Savage’s Thin-fingered Frog
  • Tink Frog


  • Colobura dirce
  • Dryas iulia
  • Heliconius erato
  • Heliconius sapho
  • Heraclides cresphontes
  • Hermeuptychia hermes
  • Metacharis victrix
  • Morpho helenor
  • Morpho Menelaus
  • Opsiphanes tamarindi
  • Phoebis argante


  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Atrocarpus heterophyllus Fruiting
  • Attalea rostrata Fruiting
  • Bauhinia variegata Flowering
  • Cascabella thevetia Flowering and Fruiting
  • Castilla tuna Fruiting
  • Citrus spp  Fruiting
  • Clusia vallerii Fruiting
  • Cocos nucifera Flowering and Fruiting
  • Crestentia alata flowering and Fruiting
  • Costus speciosus Flowering
  • Couroupita guianensis Flowering
  • Dypsis lutescens Flowering and Fruiting
  • Etlingera elatior Flowering
  • Ficus insipida Fruiting
  • Garcinia madruno Fruiting
  • Gustavia brachycarpa Flowering
  • 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
  • Inga spp Fruiting
  • Ixora coccinea Flowering
  • Lantana camara Flowering and Flowering
  • Lagerstroemia speciosa Flowering
  • Morinda citrifolia Fruiting
  • Musa acuminata Flowering and Fruiting
  • Nephelium lappaceum Fruiting
  • Pachira quinata Flowering
  • Piper auritum Flowering and Fruiting
  • Piper nigrum Fruiting
  • Piper umbellatum Flowering and Fruiting
  • Pleiostachya pruinosa Flowering
  • Plumeria rubra Flowering
  • Pseudobombax Fruing
  • Stachytarpheta frantzii Flowering
  • Symphonia globulifera Fruiting
  • Tocomeyia pittieri Flowering and Fruiting
  • Virola guatemalensis Fruiting
  • Virola Koschnyi Fruiting
  • Voschia ferruginea Flowering
  • Zammia sp Flowering




One response to “Absent With Leave

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  1. Philip, only a few weeks until we get to BDC. Can’t wait for you to show us the wildlife.


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