Archive for the ‘Walking Stick’ Tag

Phasmids: A Neotropical Walking Stick   2 comments


Wildlife, nature, fauna and flora of Costa Rica.

Sticking to the Twigs

There are some animals that live out in the open, right in front of your eyes, and yet you never see them.  That is because they don’t want to be seen.  Only when mistakenly they venture forth onto a background that reveals their presence will you have the opportunity to marvel at their disguises.  One such group of animals are the Phasmatodea, more commonly known as Walking Sticks or Stick Insects.

Last week I saw one that had made such an error.  It had left the vegetation where it lives perfectly concealed from view and had wandered onto the screen of my cabin.  There it stood out like a sore thumb.  Thankfully for the phasmid it was my eyes that saw it before those of any potential predator.  If removed the unfortunate creature and placed it back amongst some twigs from which I could take its picture but also from where it could make its way back into the obscurity of the vegetation.

Phamatodea: Walking stick in Costa Rican Rainforest

The long spindly legs and body of a Walking Stick make enable it to avoid the attention of predators

The body and legs of the walking stick are long and spindly.  They are either green or brown in color and quite often, as this one was, a mixture of the two.  The body and legs are grooved and have small thorns.  They resemble so perfectly a twig that, even when you are looking directly at them, they are imperceptible.  Some species have wings but not the one I was looking at.  They are vegetarian and tend to be host specific.  Walking sticks reach the zenith of their diversity in tropical forests such as these, of the 2,500 species identified so far, 30% live in the Neotropics.

As well as the perfectly camouflaged body form the phasmids use other means by which to complete the illusion.  This one, when disturbed, would rock back and forth as a twig being blown in a breeze.  Then it would freeze and hold the front legs as well as the long filamentous antennae out in front of its head to make to enhance its long twig-like form.

In and Out of the Rainbow

There has been a new wave of plant life that has come into bloom over the past week or so.  The cycle of change in the forest is such that throughout the year you are never short of something new to see or hear each time you venture out onto one of the trails.  As the flowers of certain species turn to fruit, then so do others come into bloom.  The flowers and fruit provide a continual annual transition of color and form.  You only have to keep your eyes open as you walk and you will be rewarded with a visual sensory feast.

Last week one of the most obvious additions to the floral display was the Recadito, (Palicourea guianensis) of the family: Rubiaceae.  The multi-clustered bright yellow flowers are borne on a vivid red stalk at the end of the branches.  They are visited a lot by butterflies, especially if found growing at the forest edge.  It is a small tree with large leaves and is reasonably common in wet habitat from Mexico to Bolivia.  There are 27 species of Palicourea to be found in Costa Rica, 3 of which occur on the Osa Peninsula.

Rubaceae of the Osa Peninsula, Costa Rica.

The distinctive floral display of Recadito, (Palicouria guianensis)

Another related plant, but much smaller and subtler is the Cafecito, (Psychotria capitata).  It too, belongs in the family: Rubiaceae but it is a very large genus, 115 of which live in Costa Rica, 40 of those on the Osa Peninsula.  They are not always easy to identify to species level.  This one, Psychotria capitata has small white flowers which when pollinated give rise to small purple berries.  At that point it resembles a rather swollen blackberry fruit.

Cafecito, (Psychotria capitata), Osa Peninsula, Costa Rica.

Delicate white flowers of the unobtrusive Cafecito, (Psychotria capitata)

Crosier for a Green Bishop

Ferns, or pteridophytes, are non-flowering vascular plants that most people who enjoy walking in the countryside will be familiar with.  You will not see fruits or seeds as ferns produce tiny dust-like spores produced in special spore cases on the underside of the leaves.  There are about 800 species of fern in Costa Rica but their form is so distinctive that they are not too difficult to recognize as such.  They are mostly low growing in shady areas of the forest but there are some that grow to a substantial size, the tree ferns.  These behemoths of the pteridophyte world, along with the cycads, were the dominant form of terrestrial vegetation before flowering plants evolved, and can be regarded as the “Food of the Dinosaurs”.

There are tree ferns found growing in these forests but they don’t reach the giant statures of those in other parts of the world.  Most of the ferns here are of the low growing type.  When a new leaf is produced it lies in the center of the plant, wound around itself like a green rope on a spool.  As the days pass it unfurls up and outward, revealing leaves that appear as an organic fractal, repeating the pattern on a smaller and ever smaller basis.  Eventually as the stalk has reached its maximum growth, the final part resembles a Bishop’s Crozier, which ultimately uncurls and the side-branching leaves and leaflets open out to reveal the familiar frond.

Pteridophytes of the Osa Peninsula, Costa Rica.

An unfurling fern frond

Mustachioed Murderer

Walking through the forest I entered a more open spot where the sun was lighting up a clearing.  I noticed something move very quickly on the forest floor.  It settled on the surface of a leaf.  I knew what it was but to begin with I was a little puzzled as it looked to possess four large eyes, so in my mind I was looking at one insect perched on top of another.  I bent down to take a closer look and I could now see my mistake.  There were most certainly two very large distinctive eyes but the dark markings contrasting with the yellow ground color of the thorax gave it the appearance of a second insect sitting on its back.  I could now also confirm my identification as that of a Robber Fly, family: Asilidae.

Robber flies are true flies of the order: Diptera and therefore only possess one pair of wings.  A distinctive feature of the robber flies is the cluster of hairs at the front of the head that give them a look of an Edwardian gentleman sporting a rather luxurious mustache.  This is known as a mystax, which is taken from the Greek word for mustache.

Why would a fly have a protective mustache of bristles protecting the front of the head?  The Robber Flies are accomplished predators and will hunt down any arthropod of a suitable size, not too small, not too large, that makes the unfortunate mistake of entering into the killer’s field of view.  The Robber Fly has large eyes and respond with speed to a potential meal.  It uses the stiletto-like piercing mouthparts to stab its victim and to inject a saliva which contains a deadly cocktail of neurotoxins and cell destroying enzymes which render the prey to a corpse being digested from within.  The fly then sucks out the pre-digested meal.  They have no hesitation in attacking wasps and ants which themselves are capable of inflicting a fatal bite or sting.  The mustache serves to protect the fly from such retribution.

Asilidae: Robber fly on the Osa Peninsula, Costa Rica.

Assassin with stilleto ; Robber fly with cockroach prey

Robber Flies prefer sunny gaps in the forest, which is exactly where I found this one.  They sit on a perch located low to the ground and wait for a meal to pass by.  Their reaction speed is so fast that in a blur of the eye they can snatch a flying insect out of the air.  You can see in the photograph that this one had just caught a tropical cockroach.  Don’t try to catch one in your hand as a stab from that proboscis is very painful.

There are about 7,500 species of Robber Fly distributed around the planet, preferring warmer areas that are arid or receive only seasonal rainfall.  They are not that hard to find, pick a sunny light gap and then you just have to sit and watch for that quick movement.

Philip Davison Is a Biologist, Writer and Photographer Based in Costa Rica

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Bosque del Cabo – Looking at the Rarely Seen   3 comments


Felipe del Bosque Blog April 1st 2013

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Mud Mosaic

Initially there had been no sign of the weather changing with the hot and dry conditions continuing throughout the week.  The creek is still flowing but the forest floor is now starting to crack intensely forming a series of polygonal reticulations.  The lawns have lost a lot of their vibrant green color and there are large scorched patches of parched grass which have become crispy and brittle underfoot.  Some of the plants on the forest edges are now turning yellow and wilting.

One small glimmer of hope is that over several nights there has been a mass of dark cloud gathering.  By early evening there was the occasional sprinkle but in total precipitation it did not amount to much, little more than a damping of the top surface of the ground.  The rains did not materialize despite the heavy dark cloud cover but it is still a little too early in the season.

Dione juno

Not Sticking Out.

Most people are familiar with walking sticks, the insects not the ambulatory aid.  All of the different species basically have the same morphological design; a long body, legs and antennae.  When they are located in amongst the vegetation they are almost impossible to see.  When stationary they hang motionless from a twig with the antennae close together and held out straight from the front of the body along with the front pair of legs.  The illusion is that of just one more spindly twiglet.  For this reason, despite the relative abundance, they are rarely seen.  You can be staring directly at one but the deception is flawless you won’t see it.

Walking sticks belong to the Order: Phasmatodea or Phasmids which consists of approximately 2,500 species divided into six families.  They are distributed globally but a large percentage exists in the neotropical forests.  They are plant eaters and closely resemble the vegetation on which they are feeding.  Some of them, particularly the males have wings and so if you pay too close attention the twig you are looking at may take to the air and disappear into the distance.  As well as the amazing cryptic form of the phasmids, they can also enhance the impression of being a plant part with behavioral displays such as swaying back and forth to mimic movement in a breeze.

Walking Stick

Mini Beaver

Sometimes while walking around the gardens you may see some plants that have the stem neatly bitten through.  Closer inspection reveals a cut not too dissimilar to the way a beaver gnaws through and fells a tree using that perfectly executed circular grooved cut.  That might lead you to assume the culprit could be a smaller rodent practicing the same destructive tendencies on a mini scale.  It sounds plausible but it is not actually what is happening.  The villain in this case is smaller still and has six legs.  Not only that but it sports two very long antennae.  It is a species of Long-horned Beetle, Family: Cerambycidae.  As with so many other beetles it is a Herculean task for many specialist coleopterists to identify them to species level but the stunning alternate orange and black segments making up the long curved antennae are enough to give me at least an identification to family level of the mystery mini lumberjack.

Long-horned Beetle

Hanging Around at Night

The Three-toed Sloth, (Bradypus variegatus), is a common mammal on the grounds of Bosque del Cabo.  It is one of those creatures that fascinate people simply because it is such a unique looking animal.  Quite often it is the first mammal people enquire about seeing when they arrive at the lodge.  They are plentiful on the grounds but not always the easiest mammal to find.

The sloth lives almost 100% of its life up the top of trees.  It is a leaf eater and leaf does not yield much energy so much in the fashion of the Howler Monkeys of the neotropics or Koala Bears of Australia they do not move much and when they do it is not very far.  The Three-toed Sloth has a territory of about 40 trees but they return frequently to a home tree called a modal tree.  The diet is not that varied especially considering the diversity of tree species growing in any one given area.  They prefer to eat younger leaves which can be found at the end of the branches.  They are aided in reaching these by having proportionately long arms in comparison with body length.

One of the best trees in which to spot a sloth is the Cecropia tree.  These have an open crown which makes viewing more accessible.  The Cecropia is also a good place for the sloth to sunbathe.  It has a very low basal metabolism and very slow passage of food through the alimentary canal, sometimes up to a month.  The sun’s energy heats up the sloths body and helps speed up digestion.  In a temporal or period of low sunlight levels the sloths can die of hypothermia.

The sloth descends to the ground every 7 days or so to defecate.  There are several theories as to why they might do this but the most plausible is the fact that the sloth being such a slow mover if it were to defecate from the tree tops, any potential predator would spot the fresh feces, look up and there is its meal sitting directly above.  That descent for a toilet trip is hazardous to a slow moving creature so once a week it takes its life in its hands, climbs backwards down a tree trunk, bores a hole in the earth with its short stubby tail and poops.  It covers the material to stop it being easily located then ascends to the tree tops to wait another week before coming back down again.

Different individuals have different food preferences in terms of the leaves they eat.  This preference is conferred on a young sloth by its mother.  It inherits the taste for certain leaves by tasting the leaf fragments on the lips of the mother.  As different individuals have a specific group of tree species from which they are taking leaf, a small area with high tree species diversity can support a larger number of sloths than it otherwise would.

This female sloth had been hanging around in the vicinity of the mango orchard near the restaurant for weeks.  Every few days it would change its location to a new tree.  One night it was hanging from a vine about 9 feet above the ground.  It didn’t appear to be doing anything in particular and didn’t seem like it was going anywhere.  I went and got the camera and took a series of pictures then departed to leave the creature to figure out what it was going to do next.

Three-toed Sloth

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

Hide and Seek

There are some animals that may be present in large enough numbers to be considered common but are not seen that often because they don’t want to be seen.  They may live in inaccessible areas or make themselves scarce upon your approach.  Two such reptiles turned up last week.

The Southern Bromeliad Boa, (Ungaliophis panamensis), is a dwarf boa not reaching dimensions anywhere similar to its more famous relative the Boa Constrictor.  It is regarded as being not very abundant but I find this species more frequently than some of the other snakes at Bosque.  This individual turned up in the Boa Bar early one evening.

These boas can be found from high in the trees to ground level in the forest.  They are normally active from dusk to dawn.  The diet consists of frogs, small lizards and small rodents.  They are very shy and placid snakes more inclined to hide their heads under the body rather than bite if disturbed.

Southern Bromeliad Boa

Basilisks are renowned for their ability to run across the surface of the water which gives them their alternative name of Jesus Christ Lizards.  They are diurnal lizards and generally can be found in the vicinity of water such as creeks, ponds, mangroves and estuaries.  As soon as you approach they will stand up on their back legs and take off running bipedally across the surface of the water.  What allows them to do that is the fact that the toes on the hind feet are long and fringed which spreads the weight of the lizard over a much wider surface area and consequently not breaking the surface tension.

This was a male Common Basilisk, (Basiliscus basiliscus), that I found sleeping in a palm near the restaurant one night.  When fully grown the males are approximately 3 feet long.  The males have a crest on the back of the head and a high fan that runs the length of the body and then the tail.  The females are smaller and unadorned.  The adults feed on a large variety of food including pond vegetation, insects, lizards, snakes, rodents and small birds.  The juveniles are more restricted to a diet of smaller arthropods.

Common Basilisk

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 0.01 ins.  Total Weekly Rainfall 0.08 ins

Average Daily Rainfall 0.3 mm.  Total Weekly Rainfall 2.0 mm

Highest Daily Temp 94°F.  Lowest Daily Temp 76°F.

Highest Daily Temp 34.3°C.  Lowest Daily Temp 24.7°C.

Species List for the Week

Mammals

  • Mantled Howler Monkey
  • Spider Monkey
  • White-faced Capuchin Monkey
  • Common Tent-making Bat
  • Western Red Bat
  • White-nosed Coati
  • Agouti
  • Alfaro’s Pygmy Squirrel
  • Red-tailed Squirrel
  • Three-toed Sloth
  • White-lipped Peccary

Birds

  • Mealy Amazon
  • Red-lored Amazon
  • Scarlet Macaw
  • Great Curassow
  • Broad-winged Hawk
  • Mangrove Black Hawk
  • Roadside Hawk
  • White Hawk
  • Golden-naped Woodpecker
  • Lineated Woodpecker
  • Streak-headed Woodcreeper
  • Black-hooded Antshrike
  • Chestnut-backed Antbird
  • Short-billed Pigeon
  • White-tipped Dove
  • Rufus Piha
  • Long-billed Hermit
  • Stripe-throated Hermit
  • Blue-crowned Manakin
  • Red-Capped Manakin
  • Spectacled Owl
  • Chestnut-mandibled Toucan
  • Cherrie’s Tanager
  • Bright-rumped Atilla
  • Buff-rumped Warbler
  • Dusky-capped Flycatcher
  • Golden-crowned Spadebill
  • Great Kiskadee
  • Great Tinamou
  • Black-throated Trogon
  • Slaty-tailed Trogon
  • Violaceous Trogon
  • House Wren
  • Black Vulture
  • Turkey Vulture

Reptiles

  • Barred Ameiva
  • Cat-eyed Snake
  • Central American Smooth Gecko
  • Central American Whiptail
  • Common Anolis
  • Common Basilisk
  • Clawless Gecko
  • Dwarf Boa
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Green Parrot Snake
  • Litter Skink
  • Mediterranean House Gecko
  • Pentaprion Anolis

Amphibians

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

Butterflies

  • Agraulis vanillae
  • Anartia Fatima
  • Anartia jatrophae
  • Caligo atreus
  • Colobura dirce
  • Cupido comyntas
  • Dione juno
  • Dryas iulia
  • Eueides lybia
  • Eurema albula
  • Heliconius erato
  • Heliconius ismenius
  • Heliconius sapho
  • Hermeuptychia hermes
  • Mechanitis polymnia
  • Mesosemia zonalis
  • Morpho cypris
  • Morpho helenor
  • Morpho menelaus
  • Philaethria dido
  • Phoebis argante
  • Phoebis sennae
  • Pierella helvina
  • Pierella luna
  • Pyrgus oileus
  • Pyrrhogyra crameri

Plants

  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Apeiba tibourbou Fruiting
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Attalea rostrata Fruiting
  • Bauhinia variegata Flowering
  • Brosimum utile Fruiting
  • Caryocar costaricense Flowering
  • Cascabella thevetia Flowering and Fruiting
  • Citrus spp  Fruiting
  • Clusia rosea Flowering and Fruiting
  • Clusia vallerii Fruiting
  • Cocos nucifera Flowering and Fruiting
  • Crestentia alata flowering and Fruiting
  • Costus speciosus Flowering
  • Couroupita guianensis Flowering and Fruiting
  • Dypsis lutescens Flowering and Fruiting
  • Etlingera elatior Flowering
  • Ficus citrifolia Fruiting
  • 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
  • Inga spp Fruiting
  • Ixora coccinea Flowering
  • Lantana camara Flowering and Flowering
  • Lagerstroemia speciosa Fruiting
  • Morinda citrifolia Fruiting
  • Musa acuminate 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
  • Psychotria sp Fruiting
  • Stachytarpheta frantzii Flowering
  • Zammia sp Flowering

 

 

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