I’m Just Mad About Saffron   1 comment


Philip Davison. Costa Rica. Blog. Nature Diaries

Tuesday 2nd February 2016

Senna to Sleep

Over the past few weeks many of the trees have started to flower.  The increasingly dry conditions stimulate blooming at this time of the year but because most of the floors are 100 foot up in the forest canopy then the only time the visitor has to see them is when flying over the forest or when the spent blooms fall to the ground and lie littering the forest floor amongst the dry leaves.  However there are some smaller trees, shrubs and herbaceous plants that grow beneath the canopy or in more open conditions.  Here you can get to see the floral display at a closer proximity.

One of those small trees generally found growing along sunny paths and roads is the Saragundi, (Senna reticulata).  Its bright yellow flowers tinged with a hint of orange stand upright like fat golden candles giving the whole of the tree crown an overall fiery glow against the green background of the forest or azure blue of the sky.  Stand beneath the tree and you will hear the constant buzz of bees attracted by its flowery display as they come to take nectar and pollen.

Fabaceae. Senna reticulata. Saragundi. Osa Peninsula. Costa Rica.

Despite its showy appearance Saragundi is not a welcome part of the native flora as far as farmers are concerned.  It is a rapidly growing weedy tree that will quickly invade and take over open areas such as pasture land and nor is it easy to eradicate.  It is little wonder that the local gardening team around here hates them with a vengeance and cut them down as soon as they germinate.

Should you see a Saragundi later in the day, more towards dusk, you will notice that the leaves start to droop and the plant goes to “sleep.”  This is a feature common to many plants in the Fabacaea family, (legumes), and it is known as a nastic response.  The base of each leaflet has a fleshy elbow called a pulvinus.  During the course of the day the rhythmic flow of potassium ions causes water to either enter or exit the cells of the pulvinus.  In the morning the large water holding cells become full of water making the pulvinus turgid which holds the leaflet out straight.  At dusk water exits the cells making the pulvinus flacid and so the leaflet folds down appearing as if to go to sleep.  It is not known what evolutionary benefit this nyctinasty conveys on the plant but it most certainly looks like some of the forest trees are dozing off for the evening.

A Rod of Gold

Growing along the currently dusty roadsides or lining the forest edge abutting the gardens are weedy long-stemmed plants that have a crown of yellow flowers atop.  These are the Jackass Bitters, (Nuerolaena lobata).  It belongs to the Aster family which includes the daisies and dandelions.  It is one of the most species rich families of plants on the planet rivaled only by that of the orchids.

The flowers heads are composites; each individual head is a group of flowers, the greater display of many flowers together provide a more attractive visual target to potential pollinators.

Asteraceae. Nuerolaena lobata. Jackass Bitters. Osa Peninsula. Costa Rica.

There is a lot of folk medicine currently based on the supposed curative properties of Jackass Bitters but none that has any scientific backing.  However its anti diabetic qualities are being scrutinized in a laboratory situation with regards to its ability to exert some control over blood sugar levels.

Canna Look at Your Lily

Tucked under the shady conditions beneath the taller vegetation where the garden meets the forest edge are a low growing plant with yellow flowers.  These are the Canna Lilies, (Canna x generalis).  It is mostly a hybridized form cultivated to bring a splash of color to leafy green flower borders.  It is not obvious from which natural species of Canna that this variety has been hybridized but it is possible that it may be a Neotropical native Indian Shot, (Canna indica).  You will seeing this variety growing freely in many garden situations around the country.

Cannaceae. Canna generalis. Canna Lily. Osa Peninsula. Costa Rica.

Going Bats for Garlic

Going for a walk through the forest this time of year may certainly cause a stimulation of your olfactory senses.  There are many scents and odors that seem vaguely familiar but you cannot quite put bring to mind what it is simply because it out of context.  Currently walking through the forest there are areas where you experience the definite smell of chives, or is it onions, no wait a minute it is garlic.  What would garlic be doing growing in a tropical rain forest situation?

Here and there along the forest trail there are patches of yellow flowers littering the forest floor en masse.  At this point the aroma of garlic is very strong.  The flowers lie for some distance concentrically around the base of a large tree which given its appearance looks more like a tree from higher temperate forests.  The bark is rough and deeply fissured, closely resembling an Oak Tree than a smooth bark tropical tree.  This is the Ajo or Garlic Tree, (Caryocar costaricense), so named because its flowers give off a scent reminiscent of garlic.

Caryocaraceae. Caryocar costaricensis. Garlic Tree. Osa Peninsula. Costa Rica.

There is very little wind in the Pacific lowland forests of Costa Rica so the plants have to rely on animal agents for pollination and seed dispersal.  Bats are very important pollinators and seed dispersers but bats prefer musky smells rather that sweet smells which is why there are some very strange odors in the forest.  It is the scent of garlic that attracts the bats in so the Garlic Tree is a bat pollinated tree.

Seeing Things in a Different Light

On the hot sunny days of the dry season many butterflies can be seen flying around the garden areas.  There are several species that are noticeable due to their striking yellow coloration.  These could be the “butter” flies.  These are the sulphurs and they are not easy to tell apart species wise unless you have them in the hand.

Pieridae. Coliadinae. Phoebis sennae. Cloudless Sulphur. Osa Peninsula. Costa Rica.

Sulphur butterflies belong in the Subfamily: Coliadinae of the family: Pieridae.  To the human eye the butterflies all have yellow coloration to a greater or lesser extent.  Some may appear to be more creamy-yellow, others lemon yellow and yet others orangey-yellow but without exception – yellow, hence the name sulphur.  But that is not how they look to other butterflies.

Pieridae. Coliadinae. Phoebis agarithe. Orange Giant Sulphur. Osa Peninsula. Costa Rica.

Butterflies, unlike humans see light at the ultraviolet wavelength of the electromagnetic spectrum.  The dorsal surface of the male sulphurs wings are colored with a yellow pigment.  This re-enforces a reflective ultra violet component that covers most of the dorsal wing surface and appears to sexually attractive to females which only have a small amount of ultra violet reflectance on their wings in comparison.  The ultra violet patterning is used by the males in courtship displays.  To human eyes the butterfly appears as a dancing honey colored piece of confetti.  The females however see something different.  Larger males with bright reflective radiance appear to be more attractive to larger females.  In the world of the sulphurs flashy show offs get the girls.

Philip Davison is a biologist, writer and photographer based in Costa Rica.

January 2016 – Hot, Dry and Wild With Life   Leave a comment


Philip Davison. Costa Rica. Blog. Nature Diaries

Weather January 2016

Max Temp 40.0ºC (106ºF)                                                      Max Low Temp 25.1ºC (77ºF)

Min Temp 34.5ºC (94ºF)                                                         Min Low Temp 21.5ºC (71ºF)

Average High Temp 39.3ºC (103ºF)                                       Average Low Temp 24.1ºC (76ºF)

Total Rainfall 42.7mm (1.68ins)

Animal Sightings January 2016

Mammals

Common Opossum

Tamandua

Nine-banded Armadillo

Greater White-lined Bat

Tent-making Bat

Western Red Bat

White-throated Capuchin Monkey

Central American Squirrel Monkey

Mantled Howler Monkey

Central American Spider Monkey

Alfaro’s Pygmy Squirrel

Red-tailed Squirrel

Central American Agouti

Tome’s Spiny Rat

Northern Raccoon

White-nosed Coati

Kinkajou

Tayra

Striped Hog-nosed Skunk

Ocelot

Puma

Collared Peccary

 

Birds

 

Great Tinamou

Great Curassow

Crested Guan

Brown Booby

Brown Pelican

Magnificent Frigatebird

Bare-throated Tiger Heron

Black Vulture

Turkey Vulture

King Vulture

Roadside Hawk

Broad-winged Hawk

Black Hawk

Crested Caracara

Yellow-headed Caracara

Short-billed Pigeon

White-tipped Dove

Royal Tern

Scarlet Macaw

Orange-chinned Parakeets

Red-lored Amazon

Mealy Amazon

Spectacled Owl

Stripe-throated Hermit

Long-billed Hermit

Purple-crowned Fairy

Charming Hummingbird

Blue-throated Goldentail

Rufus-tailed Hummingbird

Black-throated Trogon

Blue-crowned Motmot

Black-mandibled Toucan

Fiery-billed Aracari

Pale-billed Woodpecker

Lineated Woodpecker

Streak-headed Woodcreeper

Black-hooded Antshrike

Chestnut-backed Antbird

Golden-crowned Spadebill

Bright-rumped Atilla

Dusky-capped Flycatcher

Great Kiskadee

Masked Tityra

Red-capped Manakin

Riverside Wren

Mourning Warbler

Gray-headed Tanager

Summer Tanager

Cherrie’s Tanager

Red-legged Honeycreeper

Orange-billed Sparrow

 

Reptiles

 

Basilisk

Helmeted Iguana

Slender Anole

Golfo Dulce Anole

Big-headed Anole

Mediterranean House Gecko

Central American Smooth Gecko

Clawless Gecko

Central American Whiptail

Four-lined Whiptail

Mussarana

Cat-eyed Snake

Barred Forest Racer

Green Parrot Snake

Salmon-bellied Racer

 

Amphibians

 

Marine Toad

Black and Green Poison Arrow Frog

Golfo Dulce Poison Arrow Frog

Fitzinger’s Rain Frog

Stejneger’s Dirt Frog

Tink Frog

Red-eyed Green Tree Frog

Milky Frog

Bolivian Frog

Savage’s Thin-fingered Frog

 

Butterflies

 

Cogia calchas

Pyrgus oileus

Quadrus cerialis

Urbanus simplicius

Urbanus teleus

Xenophanes tryxus

Anatrytone potosiensis

Anthoptus epictetus

Callimormus radiola

Euphyes vestris

Eutocus sp

Panoquina lucas

Polites vibex

Pompeius pompeius

Saliana fusta

Synapte silius

Vehilius stictomenes

Battus polydamus

Heraclides cresphontes

Parides erithalion

Eurema albula

Eurema daira

Phoebis agarithe

Phoebis argante

Phoebis sennae

Pyrisitia nise

Glutophrissa drusilla

Arawacus lincoides

Calycopis isobeon

Pseudolycaena damo

Strymon yojoa

Cupido comyntas

Hemiargus hanno

Detritivora gynea

Mesosemia zonalis

Metacharis victrix

Mechanitis polymnia

Antirrhea philoctetes

Caligo eurilochus

Morpho helenor

Morpho menelaus

Opsiphanes tamarindi

Cissia confusa

Cithaerias pireta

Hermeuptychia hermes

Pareuptychia ocirrhoe

Pierella helvina

Pierella luna

Archaeoprepona demophon

Marpesia berania

Pyrrhogyra naearea

Adelpha cytherea

Adelpha heraclera

Agraulis vanillae

Dione juno

Dryas iulia

Eueides aliphera

Eueides lybia

Heliconius cydno

Heliconius erato

Heliconius hecale

Heliconius ismenius

Heliconius sapho

Philaethria dido

Anartia fatima

Anartia jatrophae

 

Philip Davison is a biologist, writer and photographer based in Costa Rica.

Posted February 1, 2016 by felipedelbosque in Uncategorized

Flying a Dangerous Flag   4 comments


Philip Davison. Costa Rica. Blog. Nature Diaries

Thursday 28th January 2016

Stay Behind the Barrier

Black and yellow is the most visible color combination that exists.  It follows that any creature sporting patterns in this visually obvious blend might not be trying to conceal itself.  Bees, wasps and hornets are generally striped in yellow and black.  Many poisonous spiders, butterflies and caterpillars are decked out in the same fashion.  If they are not trying to hide then they are making themselves obvious, for whatever reason they are telling you to stay away.  This strikingly acute combination of color is known as aposematic coloration or warning coloration.  Humans use it too in the form of black and yellow striped tape to keep people from getting too close to a dangerous situation.

In the area of Matapalo these colors can be frequently seen and encountered throughout the forest.  Flying along the forest rides and around the nectar giving bush Lantana camara in gardens are the brightly colored Heliconiids or longwinged butterflies.  One of the most common of these is Heliconius sapho, its yellow banded velvet black wings beating slowly interspersed between periods of short glides as it makes its way down the trails.  This aesthetic beauty is telling potential predators one thing – “STAY AWAY”.

The Postman Butterfly. Heliconius sapho.

The butterfly is unpalatable and what makes it unpalatable is the fact that it is packed with cyanide.  Having a toxic defense against predation serves no purpose if the predator does not know about it.  Eating one of these butterflies would result in the death of the butterfly and the creature eating it.  The predators learn through experience.  Once a predator, whether it be a bird or a lizard, catching and trying to feed on one of these butterflies will experience a foul taste caused by the cyanide.  It spits it out and it does not take too long before the black and yellow coloration is associated with something so wholly unpleasant that anything dressed in the same colors will be avoided with a passion.

Leaf it Alone

It is not just adult Lepidoptera that use toxic defenses; many caterpillars are prone to do the same. Frangipani, (Plumeria rubra), despite being thought of as a Hawaiian plant whose flowers are used to make the leis to put around the necks of tourists, is actually native to Central America.  It is the national plant of Nicaragua.

Frangipani continually flowers throughout twelve months of the year.  As the sun sets the pale white blossoms give off a heavenly scented sweet perfume which drifts into the night, the aroma of which attracts night-flying hawk moths.  The moths are attracted with the promise of a nectar rich feed.  But nectar is energy expensive for the plant to produce so the plant cheats the moth; it reneges on the promise and produces no nectar at all.  The duped hawk moth searches in vain but to no avail, the long proboscis probes into one flower after another and becomes covered in pollen.  Flying from flower to flower it transfers the pollen and pollinates the plant.  The moth having thus been enticed subsequently receives no reward for its labors.

There are moths that unwittingly have their revenge, the Frangipani Hawk Moth (Pseudosphinx tetrio).  The eggs of this moth are laid on the undersides of the Frangipani leaves.  Upon hatching the caterpillars are very small, only 10 – 15 mm.  They won’t stay that way for long.  After consuming their own egg shell they set about consuming the leaves with gusto.  The caterpillar is a committed eating machine; it turns plant tissue into animal tissue at an incredible speed.  They can almost be seen to grow day by day.

The last part of the leaf to be eaten is the stalk.  If damaged the stalk leaks a stiff white liquid rich in alkaloids.  The alkaloids are very toxic and would normally deter anything from consuming the leaf.  The Frangipani Hawk Moth caterpillars store the alkaloids in their bodies making them in turn highly toxic.  Once more that information needs to be relayed to any potential predator to save both parties from harm.  The vividly black and yellow hoops with a flash of bright red head, tail and legs should serve the purpose very well.  It appears to do so as these caterpillars feed in full view both day and night on the very naked limbs of the Frangipani.

Frangipani Hawkmoth. Pseudosphinx tetrio

Within little more than a week the plant will be denuded of leaves and the caterpillars will have increased to a very stout 60 – 70 mm.  Should more plant tissue be needed to complete the larval stage before pupation then the caterpillars set about consuming the rubbery branches of the tree.  One night, as if by magic, all the caterpillars will have disappeared, retiring to some secluded nook or cranny to pupate before emerging in the future as a relatively drab moth which will mate and start the process over again.  Although the Frangipani may look a little forlorn in its leaf denuded state, it really doesn’t take long for it to produce fresh growth, in fact quite often on parts of the plant as the caterpillars are still feeding.

Beware a Colorful Meal

Spiders might not be that easy to find but once you start to look they are everywhere.  In common with many other forms of life, the species richness and diversity of spiders is huge.  More obvious than most are the orb weaving spiders, the webs of some species traversing large expanses between trees.  However there are many smaller spiders with consequently smaller webs.  One of the more distinctive of these is the Arrow-bodied or Spiny-bodied Spider, (Micrathena sexspinosa).  Either name is appropriate and speaks for itself.

The body of the spider has an array of spines and thorns which in itself should be enough to discourage any potential predator.  But sometimes physical defenses can be overcome.  The spider has invested in a second insurance policy – a foul-tasting chemical defense.  As with the above butterflies and caterpillars there is no point having that means by which to avoid predation if the predator is oblivious to its existence.  So once again aposematic coloration comes into play, the spider is dressed in a black and yellow checkered pattern.

Spiny-bodied Spider. Micrathena sexspinosa.

Any naive bird or lizard that ignores the warning signs and tries to eat the spider will end up with the spider jammed in its bill or mouth by way of the spines and thorns.  All the while the spider issues from its skin a nasty tasting secretion that the unfortunate predator has to endure while trying to remove the spider from its bill or mouth.  Once the cause of the vile experience has been eliminated then the bird or lizard will probably never attempt to eat anything black and yellow again.

Tiny Timid Tigers

For the last example of black and yellow aposematic coloration we turn to the hymenoptera, more specifically the ants.  Ants like spiders may not at first be as obvious as mammals, birds and butterflies but take the time to look at little more closely and they most certainly are there.  Leaf-cutter Ants are hard to miss, their long winding ribbons of green cut leaf fragments running like verdant rivers across the forest floor.  Army Ants likewise when in a foraging frenzy move in fronts upto sixty feet across appearing as an almost large black plastic sheet being pulled across the forest floor, its intent being the slaughter and butchering of all small forms of life unfortunate enough to not be able to escape from its path.  Noisy excited attendant birds and the hum of parasitic flies usually herald its approach.

But rather than these mass movements there are many other ants that occur in smaller numbers.  Seen walking down tree trunks, along branches and roots in small lines like kids playing follow the leader are distinctive black ants with golden bands, the Tiger Ants, (Camponotus seriseivestris).

Tiger Ants are closely related to the Carpenter Ants and share the same life history as general foragers taking nectar, seeds and fruit from plants.  They attend aphids and certain Lycaenid caterpillars for honeydew as well as taking small creatures either dead or alive.  They live in colonies in hollows within dead or living trees but in much smaller numbers than Leaf-cutter or Army Ant colonies.

Tiger Ant. Camponotus sericeiventris

The name Tiger Ant conjures up visions a seriously ferocious adversary capable of doing limitless damage to any unsuspecting tourist that accidently puts his hand upon them.  In actual fact they are harmless, most certainly to humans, the name referring to the coloration rather than their nature.  They do however have a means of defense if disturbed.  The aggravated ant will turn its abdomen between its legs so the rear end is facing forwards and then it will shoot a jet of formic acid towards its aggressor.  Many ants indulging in the same defensive strategy will generally deter the cause of its ire to retreat to a safe distance.

Philip Davison is a biologist, writer and photographer based in Costa Rica.

 

To be Blunt – Seeking Supper   3 comments


Philip Davison. Costa Rica. Blog. Nature Diaries

Monday 25th January 2016

A Sinister New World Emerges

Once the sun sinks low on the horizon and the light levels fall to dusk then the daytime animals return to the safety of their nightly abodes.  There is not much twilight this close to the equator, the sun seems to fall from the sky and before you know it darkness has descended and the world around you takes on a very different atmosphere.  The calls of birds ceased some hours ago.  Those cicadas whose constant high pitched hiss has permeated throughout the hot sunlit day have now gone quiet.  Even the sundown cicadas, the white noise of which replaces their daytime cousins, have called to a crescendo the fortississimo now having fallen silent too.  The blackness that was the green lawn starts to flicker here and there with small green flashes of light as the male fireflies emerge, the twinkling stimulating a response from the females which live higher in the vegetation.  In the background a Spectacled Owl, (Pulsatrix perspicillatus), calls sounding for all the world like a distant muffled laugh.  Not too far away a ground roosting night hawk, the Common Paureque, (Nyctidromus albicollis), calls with a series of plaintive whistles.  The night shift has begun.

All the Better to See You

From somewhere hidden for the day deep in the depths of the undergrowth nocturnal snakes emerge.  There is one with a body long and pencil thin that supports a head seemingly too large and out of scale with the other dimensions.  It has large eyes, very large eyes, all the better for seeing its prey.  The snout is short and the eyes are directed forwards giving it some perspective.  The long slender body is triangular in section which reinforces the skeletal strength of what is little more than a muscular tube.  This is the Brown Blunt-headed Snake, (Imantodes cenchoa).

Brown Blunt-headed Snake. Imantodes cenchoa.

The slightness of the serpent allows it to move unnoticed through the branches and leaves which make no movement in its passing.  Like an angel of death it seeks a victim.  The tongue flicks in and out constantly sampling the air until it picks up on an odor measured in quantities at the molecular level.  The scent plume leads the snake to its source and consequently its prey, a sleeping lizard.

Lying in Peril

This lizard is a Golfo Dulce Anolis, (Anolis polylepis).  It has been active during the day waiting head down on a leaf in low lying vegetation for hapless insects to wander by.  It jumps from its ambush position, grabs the meal and consumes it in quick time.  Bouts of feeding maybe punctuated with territorial disputes of chasing interloping males from its territory or perhaps courting a passing female.  With the day’s activities at an end it retires to what would normally be the relative safety of a leaf tip to sleep for the night.  Any predator approaching on the leaf would cause vibration which becomes amplified along the length of the leaf thereby warning the sleeping lizard which awakens to the imminent danger.  It jumps off and disappears into the leaf litter below.

Golfo Dulce Anolis Lizard. Anolis polylepis.

Tonight however the lizards sleeping position is not so safe as doom is approaching from a different direction.  The Brown Blunt-headed Snake is not on the same leaf.  Its search has led it to a position on a plant in close proximity.  That long strong sinuous body reaches out across the gap.  It has already identified where its meal lies.  The lizard is oblivious to its presence.  The snake’s body draws into a series of s-shaped loops and then with lightning speed and precision the strike is made.  The lizard knew nothing of its final moment on earth, dispatched and eaten like the insects that met their fate in a similar way earlier in the day.

Upping the Ante

Not all lizards sleep at night though.  There are nocturnal lizards, the most common and noteworthy of which are geckoes.  Around the Osa Peninsula there is a very common gecko that can be found in all buildings and on the trunks of garden trees.  It is a visitor that became naturalized, the Mediterranean House Gecko, (Hemidactylus frenatus), hitching a ride from Southern Europe courtesy of human transport and wherever conditions were suitable then there it settled, not just here but in tropical conditions everywhere.  They are familiar to most people as those small creatures hanging around by house lights to catch the insects attracted in by the incandescent glow.

Asleep or not the gecko is still a meal that does not escape the attention of the Brown Blunt-headed Snake.  With a similar stealthy approach it closes in on a gecko which remains perched head down on a tree trunk waiting for insects to land.  But this hunter is about to become the hunted, the difference being this one is wide awake and alert to the danger

The snake slithers into position, the tongue confirms the gecko’s presence, the eyes focus forward and the scene is set.  The snake strikes out, the jaws agape but the gecko’s reaction is rapid and it moves just in time.  The snake does not miss its target but rather than hitting the body the jaws close and the teeth sink into the tail.  Here the gecko has another defense, the tail breaks and the snake is left with little more than a wriggling piece of tail section, not much of a meal but better than nothing.

Mediterranean House Gecko. Hemidactylus frenatus.

Meanwhile the gecko has scuttled off post haste up the tree trunk, the missing tail section being little more than a minor inconvenience.  The most important thing is that it is still alive.  That missing part of the tail will regenerate over the coming months and apart from the fact that it will be of a slightly duller color than the original there will be nothing else to show for the encounter.

Philip Davison is a biologist, writer and photographer based in Costa Rica.

The Dragon Hunters   Leave a comment


Philip Davison. Costa Rica. Blog. Nature Diaries

Monday 18th January 2016

Hair Trigger

Arachnid. Costa Rica.

Spiders are an amazingly diverse group of animals, the eighth most diverse group of animals of the planet in actual fact.  It doesn’t take long while poking around in the undergrowth to come across a spider.  Some build webs and some don’t but they can all spin silk, the orb weavers having the ability to spin upto seven different types of silk.  The non-orb weavers tend to be ambush predators, remaining motionless in a strategic location where potential prey may wander innocently by unaware of the imminent life threatening danger.  The ambush position could be on the side of a wall, atop a leaf or sitting on a flower head.

Arachnid. Costa Rica.

This Wandering Spider, (Cupiennius sp), was sitting perfectly still on a blank white wall at night.  As many spiders are nocturnal predators the eyes play a lesser part in the identification and capture of a meal but that does not imply the spider is without the means by which to locate the exact location of its prey.  The body, which at first sight looks smooth, upon closer examination can be seen to be covered in hairs of different lengths.  These hairs form part of a battery of sensitive sense organs responsive to touch, vibration and moving eddies of air currents that allow the spider to detect a passing meal in the darkness.

Wandering Spider. Araneae. Ctenidae. Costa Rica.

The majority of hairs covering the body, which give most people the heebie-jeebies with regards to spiders, are tactile and touch sensitive, the stimulus of which will cause the spider to attack or run away.  Between the shorter hairs, particularly on the legs are long fine hairs called trichobothria.  These are super sensitive to the slightest movement in air currents which can be a giveaway for any larger creature passing by which could make a nice meal.  The Wandering Spiders can even detect insects such as moths flying overhead which they jump and grab straight out of the air.

For those more stealthy prey items whose movements are too slow to disturb the air, they cannot avoid causing small vibrations of the substrate and the spiders are attuned to this also.  Around the body but more particularly around the leg joints are slit sense organs which allow the spider to detect any vibrations moving through the substrate upon which it is placed.

Whereas the Wandering Spiders rely on their tactile senses at night during the day there are spiders that actively hunt down their prey visually.  The Jumping Spiders prefer to hunt in full sun.  The most obvious feature are the large anterior eyes with which they can locate and subsequently stalk their victims.  They stealthily approach to the point where the potential meal is within striking distance.  The spider braces itself and then pounce.  The fangs are embedded upon impact, pumping venom into the victim which is held in a death grip by the front pair of legs.

Salticidae. Jumping Spider. Costa Rica.

Hunting the Hunters

The spiders may be highly adapted carnivores with specialized hunting techniques but they too in turn have predators specialized to catch and eat them.  Not the least of these are the giant Helicopter Damselflies, (Megaloprepus caerulatus), the largest damselflies on the planet.  They can be seen flying along the sunlit trails through the forest.  The peculiar motion of the blue/black tipped wings gives the impression of rotating helicopter blades.  What may at first seem like a somewhat erratic flight pattern actually has design.  The more astute observer will notice that they have the ability to fly vertically up and down as well as horizontally in and out.  But what are they seeking?  The large eyes and acute vision are scanning spider webs in front of which they momentarily hover scanning for the silken structures builder.  Once located the spider is grabbed in the legs of the damselfly which goes into reverse gear before biting off the spiders head and legs to finally gorge itself on the soft body parts.

Helicopter Damselfly. Pseudostigmatidae. Costa Rica

The damselflies can be recognized when they alight by the habit of folding the wings together over the body.  Their cousins, the dragonflies keep the wings held out to the sides when at rest. During the day it is not too often that they do rest.  Each individual has a perch from which it frequently takes off to investigate any passing creature that might make a meal or another dragonfly that might prove to be a mate or another dragonfly that might be a rival for that meal or mate.  They make aerial sorties swooping at speed, hovering in place and if unmoved to action return to the perch for a short while before they are off again on another sortie.

Dragonfly. Libellulidae. Costa Rica.

They differ from the more delicate damselflies not only by how they hold their wings but also in the structural placement of the eyes.  Damselflies have two large compound eyes widely separated on either side of the head.  Dragonflies have two large compound eyes that meet together for a greater or lesser part of their margins on top of the head.  However no matter where the eyes are placed they allow for excellent diurnal vision which combined with the unsurpassed aerobatic proficiency make these some of the masterful airborne hunters.

As we move into the dry season the hot and parched conditions stimulate many of the plants into flowering.  This is most certainly true of the orchids.  There are two orchids that can be seen blooming at the moment in the area.  One is a non native terrestrial orchid, the Bamboo Orchid and the other is a native epiphytic orchid.

Orchidaceae. Costa Rica.

The Bamboo Orchid is a native of South East Asia but is planted in many parts of Costa Rica as a beautiful ornamental edging plant.  Bamboo refers to the long erect stalk that resembles that a of a bamboo grass.  The attractive purple flowers appear throughout the year giving a nonstop display of color for the back of a flower border.

Orchidaceae. Costa Rica.

The majority of orchid species in Costa Rica are epiphytic, that is they grow on the outside of trees without harming them.  Generally to see orchids you need to be at the top of the canopy, 88% of Costa Rica’s 1400 orchid species are to be found there.  Many of the orchids flower from December into January but some may be seen flowering at any time of the year.  This particular specimen was found growing close to the ground near the base of a large tree. Due to the diversity of genera and species the identification of orchids, like so many tropical plant and animal taxa, is the realm of specialists.  For most visitors it is enough to see and enjoy the exotic blooms should you be lucky to encounter them.

Philip Davison is a biologist, writer and photographer based in Costa Rica.

 

Summer’s Muted Color Collection   Leave a comment


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THURSDAY 14th JANUARY

Blue and Brown

As the wet season fades into memory and the dry season progresses then the number of butterflies increases.  Week by week as the weather becomes warmer and drier you will start to see more and more species of butterflies and not only that but also an increase in the number of individuals.  The best place to observe the most colorful of these constantly fluttering confetti-like insects is in the open areas particularly around the nectar plants that they favor which in this area happen to be the orange/yellow flowers of Lantana camara.  Here bright poster colored, slow flying heliconiids painted in yellow, orange and red are conspicuously flitting from sunlit flower head to flower head.  The casual observer will not fail to be impressed by the constant swirling to and fro of so many different species.  Flying overhead but not landing are the sulphurs, butterflies dressed, as the name suggests, in vibrant yellows and creams.  They exhibit ultra violet markings, invisible to us, but seen by other butterflies or by humans with a U.V. filter.

Down by your feet, visiting and taking nectar from the flowers of low growing herbaceous plants, are butterflies so small as to be barely discernible.  Concentrate your attention to the level of the grass and there will be revealed a motion of tiny flicking blue wings, butterflies smaller than a fingernail.  These are some of the Lycaenids, the Cenaurus Blue, (Hemiargus hanno), and the Eastern Tailed Blue, (Cupido comyntas).  Their delicate form and intricately patterned wings decorated with dark spots, pale dashes and splashes of red can only really be appreciated if you lie down at their level and watch them close up.

Butterflies. Lycaenidae. Costa Rica.Butterflies. Lycaenidae. Costa Rica.

Moving into the forest beneath the umbrella of the canopy which casts the forest floor into shade a whole other group of ground hugging butterflies can be seen, but once again only with patience and a sharp eye.  Most of these butterflies disappear as soon as they alight amongst the dead leaves or on the textured bark of trees.  The satyrs have a ground color in shades of grey and tan.  Overlying this are streaks of browns in ochres and chestnut.  They look like the leaves amongst which they settle.

Butterflies. Satyrinae. Costa Rica.

Butterflies. Satyrinae. Costa Rica.Butterflies. Satyrinae. Costa Rica.

There are several species of butterfly in the same subfamily as the brilliant Blue Morphos that do not have the bright blue coloration.  One of them, the White-signed Morphet, (Antirrhea philoctetes), looks more like a satyr than a morpho.  It is a beautiful tan and chocolate brown with darker dashes, black dots and a white stripe across the underside of the fore and hind wings.  It also sports a distinct eyespot.  Just as the earthy colored satyrs, the White-signed Morphet never flutters more than a few inches above the ground.  When it lands it remains motionless blending in perfectly with the background.

Butterflies. Morphinae. Costa Rica.

Another butterfly that remains unmoving on the side of tree trunks is the Owl Butterfly.  Having been unnoticed the close proximity of a walker on the trail may cause the butterfly to take to the air.  But not for long as it quickly settles head up on the trunk of another tree.  If you approach slowly you can see the intricate patterning of browns, tans, creams and yellow overlain with wavy black bands.

Butterflies. Morphinae. Costa Rica.

The most distinctive and distinguishing feature is the large eyespot on the underside of the hind wing that gives the butterfly its name – Owl.  The large dark bordered ring with a central pupil, along with white spots that mimic a catch light look just like an eye.  The illusion is deliberate.  This is a bullseye, a target for potential predators.  A bird, a lizard or a mouse will attack in the area of the eye because normally lying behind the eye is the major part of the central nervous system – the brain.  Wipe out the brain and the prey is killed instantly.  In the case of the butterfly the target is placed on a non vital area of the hind wing that the butterfly can afford to lose without it hindering its ability to fly.  All the predator disappointedly ends up with is a tatty piece of wing membrane.  As can be seen in the photo the Gold-edged Giant Owl, (Caligo atreus), the hind wing shows evidence of a previous attack.

Everywhere and Nowhere

A common question asked by visitors to the tropical forests is “Where are all the mushrooms?”  The fungi are most certainly here, the extensive mycelia of which permeate the soil reaching into and spreading throughout any dead organism whether it be animal or vegetable aiding in that process of rapid decay and decomposition.  But in these warm wet forests conditions are ideal all year round for the production of those familiar reproductive spore producing bodies – the mushrooms and toadstools.  In higher latitudes the almost overnight appearance of such a rich variety of fungal fruiting bodies is a visual treat for hikers in the forests and mountains.  But it is an all at once autumnal phenomenon.  Within a month or so the event has ended.  Here if you look carefully there will be mushrooms but not in such profusion or rich abundance.

Fungi. Agaricales. Costa Rica.Fungi. Agaricales. Costa Rica.

Fungi. Agaricales. Costa Rica.Fungi. Agaricales. Costa Rica.

This was a group of agaricales that were found growing on decomposing lawn mowings which had been discarded at the forest edge.  They were in various stages of fruiting from small and unopened to fully extended caps.  Actually the mushroom will grown very quickly overnight, open, shed millions of spores into the air and can have gone within 24 hours.  There are many animals that enjoy taking advantage of this sudden appearance of a tasty meal with flies laying eggs from which the larvae emerge very quickly to feed and develop.  Mice and squirrels enjoy the fungal feast as long as they are not poisonous, something humans have to be very wary of as there are some deadly toadstools out there.  Better to appreciate and enjoy the texture, form and function of these interesting ephemeral appearances than risk sampling the terminal flavor of an exotic final meal.

Jumping to an Identification

Orthoptera. Acreidae. Costa Rica.

Crickets, katydids and grasshoppers can be found in all tropical terrestrial ecosystems during both day and nighttime hours.  They might not be the easiest things to see but hearing them is unavoidable.  Although they all belong to the order: Orthoptera there are differences between the three groups.  Most familiar grasshoppers are brown or green and have short stubby antennae.  Grasshoppers make raspy sounds known as stridulation by rubbing the femur of the hind leg against either the front or hind wing.  Katydids are an elegant group consisting of many forms and colors.  Some not only have the green coloration of vegetation but have evolved remarkable mimicry with the wings resembling the veins and patterning of leaves against which they are almost indistinguishable.   Katydids, along with crickets, stridulate by rubbing the forewings together.  Katydids tend to have more pleasant calls than the grasshoppers but are not as melodious and musical as the crickets.  Both katydids and crickets tend to have long filamentous antennae.  Grig is an older English term for the jumping insects of the order: Orthoptera but these days generally refer to a separate family of katydids.

Orthoptera. Tettigoniidae. Costa Rica.

Philip Davison is a biologist, writer and photographer based in Costa Rica.

A New Age Begins   3 comments


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Week Ending 11th December 2015

Weekly Weather

Average High Temp 101ºF (38.3ºC)               Average Low Temp 75ºF (24.3ºC)

Average Rainfall 1 ins (25.4mm)                    Total Rainfall 7 ins (177.8mm)

Wet and Dry

The dry season at Bosque del Cabo Rain Forest Lodge always experiences a stuttered beginning.  The lodge is located on the south west tip of the Osa Peninsula, Costa Rica overlooking the Pacific Ocean to the south and the Golfo Dulce to the east.  The region is covered by some of the last remaining tropical forest on the Pacific Coast of Central America.  Due to the pronounced seasonality of the area having a profoundly dry five months followed by a wet seven months the forests here are more correctly classified as tropical seasonal forests as opposed to tropical rain forests which are not subject to the annual dry period.

The heaviest rains of the year fall between September and November.  By December the daily deluge abates and we gradually see more of the sun.  It is easy to be lulled into a false sense of “the summer is here” as commonly a few dry, bright days with blue skies will be followed by another week of torrential downpours.  But eventually the faltering weather passes through the transitional phase and settles into a more predictable pattern.  Given a few weeks of steady, dry heat and the plant life will begin to flower.  The number of butterfly species and individuals that had dropped in the wet season begins to build once more so the days are now filled with beautiful, brightly colored wings adorned in poster reds, yellows and orange dancing around the flower heads.

There is never a shortage of mammal or bird sightings.  Currently there are many migratory warblers and tanagers chattering noisily in mixed flocks as they move from tree to tree in search of insects or fruit to eat depending on their specific diet.  The resident bird populations do not mind those long distance travelers returning to spend the winter in the warmer climes of the tropics and join quite readily with their travelling cousins in large flocks.  Monkeys abound in the trees, constantly on the move looking for food whether it is flowers, young leaves, fruit or insects.  Under the trees the large ground living rodents, Agoutis, feed on the fallen fruit and large heavily coated seeds.  Solitary male White-nosed Coatis are on the lookout for anything they can get their paws on; grubs, crabs, bird’s eggs and chicks as well as fruit or discarded food in the bins of the restaurant.  The gregarious females with young patrol in large foraging packs looking for the same food as the males but not with the same bold abandon.

The peace of the hot still sultry afternoon atmosphere is occasionally permeated by the call of a mammal or bird.  The ever active Spider Monkeys let out a series of high-pitched shrieks which sporadically turn into a hysterical frantic screaming match.  From deep in the forest the doleful Howler Monkeys bark and roar their disapproval of some irritation.  The White-faced monkeys oblivious to the presence of human observers chitter and chatter amongst themselves.  Coming from the surrounding vegetation are the chirps and cheaps of the warblers and tanagers.  But for the most part the soporific pulsating heat and the throbbing silence serve to create a languid attitude for visitors to the tropics.

Feed Me

All of a sudden the siesta is interrupted by a harsh ear-piercing screech.  Several birds of prey inhabit the area and neither the hawks nor the falcons have been blessed with a melodious call.  Commonly seen sitting at the top of the palms or on the ground are the Yellow-headed Caracaras, (Milvago chimachima).  Despite their raptorial appearance these elegant members of the falcon family are generally carrion feeders.  They can also be seen riding the backs of cattle feeding on bovine ticks.  Due to their association with cattle they are commonly seen in open pastureland.  Until 1973 they had not been recorded in Costa Rica but following widespread deforestation their distribution and geographical range spread north from Panama into Costa Rica and they can now be seen in Nicaragua.

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That nasty nasal screech was an adult Yellow-headed Caracara calling from on the ground but there was another call, similar yet more urgent.  Not too far from the adult was a newly fledged youngster that was making its first foray from the nest.  It had not yet mastered the art of flight and was demanding food from the parent bird that was watching warily over its offspring’s pitifully laborious progress hopping and jumping across the ground.  The brown speckled shabby looking youngster bore little resemblance to its sleek yellow-faced dark-browed parent standing guard over its precarious and vulnerable position.

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From Sublime to Ridiculous

Another bird seen either high or low is the Turkey Vulture, (Cathartes aura).  As you look up into the deep blue tropical sky it is likely that you will see flocks of birds soaring on the thermals.  Silhouetted against the azure background the shapes and shades circling above you will help discern the different species present.  Long thin wings bent back from the center like a Batman motive combined with a forked tail easily characterize the Magnificent Frigatebird.  A huge bird with broad, wide wings fingered at the end and divided into a monochrome white leading edge and black trailing edge leave no mistake that this is a King Vulture.  Similar in shape but uniformly dark except for grey fingered tips is the Black Vulture.  Soaring with them with the same wing form but with longer tail and complete grey trailing edge is the Turkey Vulture.

On the ground there is no mistaking the Turkey Vulture for its head bare of feathers is bright red.  Like the Yellow-headed Caracara the Turkey Vulture feeds on carrion but unlike its falcon cousin which locates food visually, the vulture has a highly developed olfactory sense and can locate the chemical signature of decomposition following the plume of molecules of death to their source hidden beneath the forest canopy.  They can often be seen beneath the palm trees feeding on the fallen palm fruit.

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Vultures are not everyone’s favorite bird but they play a vital ecological role in disposing of rotting carcasses and rubbish that won’t make to a landfill site.

Fruit and Nuts

Sitting beneath the palm trees in the company of vultures one will more often than not see Agoutis, (Dasyprocta punctata).  These large ground living rodents are related to Capybaras, Coypus, Pacas and more familiarly Guinea Pigs.  Along with the vultures they are waiting for the palm nuts to fall.  Agoutis are essentially seed eaters and have the ability to sit back on their haunches while holding the seed in their front paws which they can manipulate and turn allowing them to easily gnaw through very tough seed coats such as nuts.

At the moment there are a lot of fruits on the grapefruit tree which when ripe fall.  Eagerly awaiting this softer option dropping from above there are some Agouti individuals that pick up the sizable citrus prize in their mouths and carry it off to be eagerly consumed.  They do not eat the peel but rather the soft juicy segments inside.

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Whereas during the day vultures and Agoutis can be seen frequenting the palm trees at night it is possible to see another creature that utilizes the palms.  If you look a little more closely at what might seem like old and dropping palm fronds you will see that they will have had another force at work.  Something has nicked through the veins of the frond to be point where it folds over.  Take a look inside and there you will most likely find the culprit responsible for this chiropteran topiary – the Tent-making Bats, (Uroderma bilobatum).

The Tent-making Bats use the tents as either day roosts or night roosts.  If they are using them as a day roost there can be as many as forty bats hanging under the frond.  They regularly change the location of each roost they are using as predators would quickly figure out where to get an easy meal.  One of the commonest predators of the tent making bats are the Squirrel Monkeys.  During the day they identify which roosts are being used by the bats climb to the fronds above and then drop onto the roost.  The startled bats come fluttering from underneath where they are picked off by the monkeys.

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Currently they are being used as night roosts.  Once the sun has set the bats leave the day roosts and fly to the selected night roosts where they wait until it is very dark before they go foraging for food.  The Tent-making Bats are fruit-eating bats and use night roosts which are never more than 80 – 100 meters away from the nearest fruiting trees which in this area are figs.  The carry the figs in their mouths back to the night roosts whereupon landing they then hold the fruit between their wings, peel off the skin with the teeth and eat the pulp.  Just before the sun rises they leave the night roosts and return to the day roosts where they will pass the day sleeping.

Philip Davison is a biologist, writer and photographer based in Costa Rica.

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