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Felipe del Bosque Blog July 23rd 2012

Felipe del Bosque

Veranillo

The weather is not as yet falling into any distinct pattern.  The heavy rain that heralded the start of the wet season had stopped and although thunder still rumbled around the skies, it was not accompanied by precipitation.  The creek remained dry and no water was going over the fall.  The capricious nature of the weather was providing intermittently ideal holiday conditions for the guests to Bosque del Cabo; sunny days and rain at night.  But towards the end of the week that situation changed, the rain at night turned into violent thunderstorms with torrential downpours.  For several nights in succession the forest was lashed with a deluge of heavy rain.  Branches and trunks could be heard snapping and breaking under the aqueous onslaught.  But this is a rainforest and it is all part of the cycle that has continued for millennia.

This time of year, the end of July through the beginning of August, the south westerly region of Costa Rica experiences what is known as a “veranillo” or little summer.  We are still in the wet season but the rains stop for a couple of weeks and everything dries up providing climatic conditions similar to those found in the dry season.

What causes the veranillo is the position of the earth at this point relative to the position of the sun.  As the earth’s inclination and orbit around the sun change over the course of the year the area known as the Inter Tropical Convection Zone is moves south from its northerly extreme on the 21st June until it passes over the equatorial region once again where it will be over the equator on 21st September.  The Inter Tropical Convergence Zone is known by those nautical folk as the doldrums.  The direction from which the wind brings the cloud and their cache of rain changes creating a temporary lull before the real rains arrive in September.

Cat Man

There were two cat sightings this week at the lodge.  A female Puma was seen by Casa Miramar.  The individual in question was the Bosque del Cabo resident female “Half-tail”.  Over the past few years she has raised several sets of cubs in the area around the Titi Trail and once again this year she has been identified as being pregnant so we await news and further sightings to monitor the progress and birth of the cubs.

One family staying with us had one of their sons walk up to the waterfall along the Bosque creek on his own.  Part way up he heard some small rocks being dislodged and falling down the bank.  He was sure he was looking at a sleek black cat and from his description, in all likelihood it was a Jaguarundi he had observed.  Of the few Jaguarundi sightings that occur at Bosque each year, most of them are in or near the vicinity of the creek.  Jaguarundis are not necessarily rare cats but are shy and therefore elusive so this particular boy had been very fortunate to get so close to one.

Snubbing Variations on a Green Theme

On one of the days when I had no one to take out on tour I thought I might go and see if I could find some new subjects to photograph.  As I walked through the forest, not too far from my cabin, I saw a small, long, green shape move around the trunk of a small tree to the opposite to myself.  As I slowly circled around to get a closer look I could see it was a Green Canopy Anole, (Norops biporcatus).  As I moved, the lizard moved, always with one eye on me but always on the far side of the trunk and with each maneuver slightly higher up.  I managed to get myself into a position to get a photo before it finally made one last scurry up and out of shot.

Green Canopy Anole

Not much further into the forest, but this time heading down a tree not up, was another of the anolis species, the Pug-nosed Anole, (Norops capito).  In contrast to the leafy green coloring of the Canopy Anole, this species is green, brown, grey and tan, colors that are all woven together into a hazy cryptic pattern that would blend the lizard into most any mottled background.  As it relies for the camouflage effect it doesn’t move but rather clings to the trunk and remaining motionless hopes you won’t see it.  I did see it but took advantage of its static stance no more than 3 feet off the ground to get some photos.

Pug-nosed Anole

There are 21 species of anolis lizard in Costa Rica, 6 of which occur on the Osa Peninsula.  They range in size from large to small and the above two species fall into the former category.  The Green Canopy Anole inhabits tree trunks in the canopy and feeds largely upon beetles and ants.  The Pug-nosed Anole, instantly recognizable due to its short stubby snout, prefers lower regions of trees that have large buttressed roots.  Their diet consists more of spiders, crickets and caterpillars which it forages from the forest floor.  Both of these species will also eat smaller anolis lizards.

Anolis lizard males have a loose flap of skin under the chin which is attached to a rod of cartilage over which they have muscular control.  When the flap of skin, or dewlap to give it the correct title, is extended it serves as a brightly colored flag to intimidate and scare off other males or court females in his territory.  Each species has different colored dewlap, the Green Canopy Anole having deep postbox red while the Pug-nosed Anole has yellow ochre.

An Eye for an Eye

At the moment there are lots of fruits lying on the ground as you walk the forest trails that have fallen from a number of different tree species.  One of the most copious producers of fruit are the figs and one species in particular, Ficus insipida, produces very large succulent, but as far as humans are concerned, tasteless figs.  If you find yourself underneath one of these trees in fruiting season it is like standing under a rain of falling mushy meteorites.

As the figs decay and ferment, they attract in the adult Blue Morpho butterflies.  Blue Morphos are large and spectacular butterflies but defy all attempts to get a picture of the open wings showing that bright blue shock of color.  One of the tricks to doing so is to find some rotting figs.  If there any morphos feeding there and they get spooked, they will take off and fly up and away. But if you just wait motionless, before too long they will return, the feast is too much of an opportunity to pass over.  They land and then flick their wings open and closed a few times.  If you can synchronize clicking the shutter with the opening of the wings, you will get the shot blue you were seeking.

As I was walking along on one of the trails, I startled a female Morpho menelaus into flight.  Unfortunately she settled on a leaf some 10 feet above me but still in a position where I could get the underside of the wing.  Although the females are not as strikingly blue as the males, the pale powder blue they display is still attractive.  The underside of the wing tends to be more patterned with distinct eye-spots but is still quite pretty without being too garish.

Morpho menelaus

The coloration exhibited by most butterflies is produced by pigmentation, with the morphos it is a result of the refraction of light.  Butterflies are Lepidoptera which means “scaled wings”.  On close examination, it can be seen that the wings of a butterfly are covered in tiny overlapping scales which in the case of the morpho are transparent and layered causing them to act as a prism.  The light passed through the scales and it is the blue light that is refracted back out.  At Bosque there are 4 species of butterfly, 3 of them are blue and 1 is white.

When you watch a morpho flying you will see it has a very erratic flight path, up and down, left to right.  As it opens its wings the dorsal surface gives a bright flash of blue, when it closes its wings the ventral surface is cryptically colored and it disappears.  Any predator trying to follow the flight path of a morpho, (with a flying butterfly that is generally going to be a bird), with get the stroboscopic effect of blue flashing light appearing in front of it making it impossible to catch.  But wherever there is a system there will be a way round that system.  There are birds, Jacamars, they are related to kingfishers, that have learned to intercept the morpho on its flight path so the perches of Jacamars normally have lots of discarded morpho wings beneath where they eaten the body and let the wings fall to the ground.

On a separate occasion, while walking on a trail I saw a butterfly that I find every now and then but not commonly, a riodinid, Mesosemia zonalis.  Although I happen across it once in a while I have never managed to get an image.  This individual was flitting from leaf to leaf on low growing vegetation.  I tried to get into a position to get a good shot but every time I had the camera ready, the butterfly flew off.  Eventually I managed to get one or two shots before it fluttered out of reach.  As is the case with many riodinids, nothing is known about its early life history or the plants on which the larvae feed.

Mesosemia zonalis

Nocturnal Assassins

In contrast, one night when I went back to my cabin there was an Automeris sp of moth caught in the sticky threads of a spider’s web.  The small dark but menacing looking arachnid had delivered its poisonous and ultimately fatal bite into an insect that dwarfed it.  As they moth slowly succumbed to the lethal injection it flicked forward its forewings to reveal a now obsolete defense mechanism, the large eye-spots that normally serve to intimidate and scare off a potential predator.  They may well provide that momentary distraction against other creatures but proved to be no deterrent against the diminutive black assassin lurking off to one side waiting in anticipation of sucking out the moth’s liquefied innards upon its demise.  If the warning is ignored the body is festooned with a covering of urticating hairs which may prove very distressing to anything other than a spider attempting to eat it.

Automeris sp

Automeris moths belong to the family Saturniidae which also contains the giant silkmoths.  They do not feed in the adult stage which is simply the reproductive and dispersal stage in the organisms life cycle consequently the adults are very short lived.

Long Variations on an Eight-legged Theme

Two arachnids turned up this week that I have been trying to photograph for some time.  One was a spider and the other an amblypygid.  The spider was an Net-casting Spider.  It has a long body and a eight very long legs which it holds in four pairs like a cross from the body.  Happy as I was to photograph the spider itself, it was actually a behavioral aspect of the spider’s natural history I was more interested in.

Net-casting Spider

Where the front 4 legs hand down beyond the head of the spider, it spins silk that is held with the tip of each of these legs.  When the legs are pulled apart, the silk is stretched into a rectangular frame which encloses within it a net of fluffy non-sticky silk called cribellate silk.  Should any naïve prey item stumble past, unaware of the death trap looming over its head, the Ogre-faced Spider drops down on a silken line, its legs in an every widening stance, it drops the net on the unfortunate victim and the legs close.  The silken net entangles the prey, which now securely enmeshed cannot escape, and succumbs to the miniature monsters venomous bite.

Net-casting Spider

Net-casting spiders have two huge eyes situated at the front of the head.    Although not much larger than the large eyes of the visually acute Jumping Spiders, the Net-casting Spiders eyes are 2,000 times more sensitive to light with the equivalent f 0.6 camera aperture.  This means even in total darkness, nothing will escape the all seeing eyes of these spiders.

The amblypygids are commonly called Tailless Whip Scorpions and although they are of the same order as spiders and scorpions they are in fact neither.  Amblypygids are nocturnal and if you visit the banks at the side of the road at night you will notice a lot of varying sized holes that play home to a host of different animals; crabs, ants, crickets, spiders and scorpions.  The night I went out to take the pictures there was a small tarantula sitting outside one of the holes.  There were plenty of Long-legged Crickets sitting on the bank.  But every few feet along the bank side were the subjects of my search, Tailless Whip Scorpions.

Tailless Whip Scorpion

At first look they are not the most handsome looking of creatures.  The head and thorax are fused into the cephalothorax whereas the abdomen is shaped like a Bishops mitre.  Being an arachnid it has the required 8 legs but at first glance you can only see 6.  Look again and you find that one pair of legs has been highly modified into very long filamentous thread-like legs.  These are covered in minute sensitive hairs that can detect the movement of any prey item in the vicinity simply by the small eddies in air currents its movements create.  The modified legs are swept back and forth until a food item is located.  At the front of the head are two appendages called pedipalps.  In the Tailless Whip Scorpions these are folded like two arms bend inward at the elbow.  The inside edges of the pedipalps are lined with needle-sharp spines.  The Amblypygid as it slowly approaches the unsuspecting victim opens the pedipalps which are now ready to grap and hold the prey in a deadly embrace from which escape is impossible.

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.

www.bosquedelcabo.com

 Photo Feature

 Cold Case Lacking in Forensic Evidence

There are many species of bird on the Osa Peninsula, well more species than mammals, reptiles and amphibians, but not in the same realm of figures as the butterflies and other insect orders.  Sometimes the birds can be seen nesting although by nature the nests normally have to be hidden from the hunger filled eyes of their predators that would make short work of any easily available and defenseless meal such as eggs and chicks.

Stripe-throated Hermit

Occasionally we have Long-billed Hermits, (Phaethornis longirostris), nesting by the side of the restaurant.  This week I found of a nest of the closely related Stripe-throated Hermit, (Phaethornis strigularis), on a path behind the bar.  Both of these hermit species construct small cup-shaped nests on the underside of a long leaf at its tip.  This means while there are eggs and chicks in the nest, as well as the incubating female, the leaf acts as an umbrella to stop the nest being constantly soaked.

Stripe-throated Hermit Eggs

The nest is constructed from fragments of moss and dry leaf that is sew together and held to the leaf by stolen spider silk.  The internal cup is lined with soft fluffy vegetation which provide a soft, almost cotton wool base for the eggs to rest upon.  The eggs will hatch about 17 days after being laid.  The female has sole responsibility for incubation of the eggs and subsequent raising of the chicks.  Until they fledge the chicks need a constant supply of regurgitated nectar and insects to provide both energy and protein.  After 3 or 4 weeks the chicks will leave the nest then go off and fend for themselves.

Stripe-throated Hermit

After I took the photo, I had to head off to Panama for a short while.  When I returned, the nest was still in place but there was no sign of the female, eggs or chicks.  There is a very low success rate with breeding birds in the tropics.  Along with everything else there is a high diversity as well as great numbers of individual predators.  One of the most frequently seen snakes in the area of the lodge is the Tropical Bird-eating Snake and although I don’t have the numbers, I have seen them consuming eggs and chicks from many of the bird nests in the area of the restaurant.  Without any evidence it is hard to say what may have been the fate of this nest but the bird eater would be high on the list of suspects.

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 1.0 ins.  Total Weekly Rainfall 7.02ins

Average Daily Rainfall 25.5 mm.  Total Weekly Rainfall 178.3 mm

Highest Daily Temp 88°F.  Lowest Daily Temp 75°F.

Highest Daily Temp 29.5°C.  Lowest Daily Temp 23.5°C.

 

Species List for the Week

Mammals

  • Central American Squirrel Monkey
  • Howler Monkey
  • Spider Monkey
  • White-faced Monkey
  • White-nosed Coati
  • Agouti
  • Nine-banded Armadillo

 

Birds

 

  • Mealy Amazon
  • Orange-chinned Parakeets
  • Red-lored Amazon
  • Scarlet Macaws
  • Grey-necked Woodrail
  • Great Curassow
  • Roadside Hawk
  • Pale-billed Woodpecker
  • Chestnut-backed Antbird
  • Black-hooded Antshrike
  • Common Paureque
  • Short-billed Pigeon
  • Long-billed Hermit
  • Stripe-throated Hermit
  • Blue-crowned Motmot
  • Red-capped Manakin
  • Fiery-billed Aracari
  • Chestnut-mandibled Toucan
  • Great Kiskadee
  • Black-throated Trogon
  • Great Tinamou
  • Riverside Wren
  • Orange-billed Sparrow
  • Black Vulture
  • Turkey Vulture

 

Reptiles

 

  • Barred Ameiva
  • Basilisk
  • Central American Smooth Gecko
  • Central American Whiptail
  • Clawless Gecko
  • Four-lined Ameiva
  • Golfo Dulce Anole
  • Green Canopy Anole
  • Mediterranean House Gecko
  • Northern Cat-eyed Snake
  • Parrot Snake
  • Pug-nosed Anole

 

 

Amphibians

 

  • Banana Frog
  • Black and Green Poison Arrow Frog
  • Gladiator Frog
  • Golfo Dulce Poison Arrow Frog
  • Marine Toad
  • Red-eyed Green Tree Frog
  • Smoky Jungle Frog
  • Tink Frog

 

Butterflies

 

  • Agraulis vanillae
  • Anartia Fatima
  • Anartia jatrophae
  • Archaeoprepona demophon
  • Dryas iulia
  • Eurema daira
  • Eurybia lysisca
  • Glutophrissa drusilla
  • Heliconius erato
  • Heliconius hecale
  • Heliconius ismenius
  • Heliconius sapho
  • Heraclides cresphontes
  • Hermeuptychia hermes
  • Mesosemia zonalis
  • Morpho helenor
  • Morpho Menelaus
  • Parides erithalion
  • Philaethria dido
  • Pyrgus oileus
  • Urbanus simplicius

 

Plants

 

  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Anthurium salvinii Flowering
  • Apeiba tibourbou Flowering
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Aspidosperma spruceanum Fruiting
  • Astrocaryum standelyarum Fruiting
  • Atrocarpus heterophyllus Fruiting
  • Averrhoa carambola Fruiting
  • Brownea macrophylla Flowering
  • Cascabella thevetia Flowering
  • Chamaedorea costaricana Fruiting
  • Cocos nucifera Flowering andFruiting
  • Crestentia alata flowering and Fruiting
  • Costus speciosus Flowering
  • Couroupita guianensis Flowering and Fruiting
  • Dipsis lutescens Fruiting
  • Ficus citrifolia Fruiting
  • Ficus insipida Fruiting
  • Gustavia brachycarpa Flowering
  • Hedychium coronarium Flowering
  • Heliconia chartacea Flowering
  • Heliconia latispatha Flowering
  • Heliconia pogonantha Flowering
  • Heliconia psittacorum Flowering
  • Heliconia rostrata Flowering
  • Hibiscus rosa-sinensis Flowering
  • Hymenaea coubaril Fruiting
  • Ixora coccinea Flowering
  • Lacistema aggregatum Fruiting
  • Lacmellea panamensis Flowering andFruiting
  • Lantana camara Flowering andFlowering
  • Lagerstroemia speciosa Flowering and Fruiting
  • Mangifera indica Fruiting
  • Miconia argentia Fruitin
  • Morinda citrifolia Fruiting
  • Musa acuminate Flowering andFruiting
  • Naucleopsis uliae Fruiting
  • Pandanus tectonus Fruiting
  • Piper auritum Flowering and Fruiting
  • Piper umbellatum Flowering and Fruiting
  • Pleiostachya pruinosa Flowering
  • Psidium guajava Flowering andFruiting
  • Stachytapheta frantzii Flowering
  • Terminalia catappa Flowering
  • Tocoyena pittieri Flowering and Fruiting
  • Virola koschnyi Fruiting
  • Vochysia ferruginea Fruiting

 

 

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