Archive for the ‘Army Ant’ Tag

ARMY ANTS:  A LIVING WAVE OF BLACK DEATH   6 comments


Veridion Adventures. Philip Davison. Rainforest animals. Rainforest plants

November is upon us.  The wet season continues, relentless heavy rain falling if not all day then at least part thereof.  One day last week over 14 inches of rain fall in an overnight deluge.  The following day the forest trails were more akin to newly formed streams, the water flowing downhill until it reached a point where it could tumble into the main creek that runs through the grounds, swelling its volume and increasing its velocity to that of a raging torrent.   There have been some dry, sunny days and if the weather continues its normal pattern then progressively as we move through the month the number of rainless days should increase.

I have been away for a month and upon my return, as with each and every year, the first thing I hear is the call of the Summer Tanager, (Piranga rubra), which has spent the summer in North America.  Not much has changed in the area while I was away.   The resident wildlife can still be found without any effort.  The White-nosed Coati, (Nasua narica), populations are growing at a steady and sustained rate.  I have never seen as many wandering the grounds as I do now.  The solitary males are normally bold creatures, but the females tend to be shy and retiring.  Now, however, the females and their young will allow you to approach very close without scurrying off into the shelter of the trees.

Rainforest lizards. Costa Rica. Polychrotidae. Anolis osae. Osa Anole. Philip Davison. Veridion Adventures.

Osa Anolis, (Anolis osae)

The wet conditions have proved to be conducive in allowing the amphibians to continue their courtship and breeding.  There are not so many egg masses present as in the main breeding period, (May – July), but there are still several species spawning on a nightly basis.  Feeding on the eggs are the Cat-eyed Snakes, (Leptodeira septentrionalis), which can be found every night by the pond.  The ever-present anoles of several species can be seen in the forest.  The commonest and most obvious is the Osa Anole, (Anolis osae), with its bright orange dewlap.  If one male is signaling to another to leave his territory then you can’t miss that flash of color against the dark background.

Ants Are Everywhere

Ants are ubiquitous insects in the forest.  On the trees you will see lines of Tiger Ants, (Camponotus sericeiventris), walking in line, foraging for food.  They receive their name from the black and yellow coloration rather than an aggressive nature.  In the lawns you would be well advised to avoid stepping in those small powdering mounds of earth that betray the presence of Fire Ants, (Solonopsis sp), living just beneath the surface.  I have never known anything so small cause so much pain as the fire ants.  The problem is that they are so small you don’t know you are covered in them until they start to bite and they all do so together.  It would be almost impossible to miss the presence of Leaf-cutter Ants, (Atta cephalotes), in these forests, whether it be descending the tree trunks with freshly cut leaf fragments or seeing lines of ants moving as a green river, snaking across the forest floor as they make their way back to, the nests with, what essentially is composting material for their fungus gardens.  Leaf-cutter Ant nests occur every 100 meters or so in whatever direction throughout the forest and can easily be identified by the large waste tips of excavated material marking the nests’ peripheral boundaries.

Rainforest insects. Hymenoptera. Formicidae. Atta cephalotes. Leaf-cutter Ant. Philip Davison. Veridion Adventures.

Pebble-capped towers formed by heavy rain on Leaf-cutter Ant nest waste tip

Army Ants:  A Living Wave of Black Death

It is a warm day, the rain has stopped, the sun is shining and you are quietly walking through the forest, binoculars strung around your neck and camera in hand.  The air is still and there is little sound bar the occasional call of a bird here and there and the soft white noise of calling insects which is not too intrusive.  You walk in a state of reverie, not thinking about anything in particular, your eyes scanning the vegetation for small subjects to photograph or watching for movement that may indicate a bird or mammal is moving across your path.  It is a day for enjoying your surroundings and contemplating the life contained within.  You are blissfully unaware of the carnage being carried out in the forest ahead.

As you make your way forward you start to hear more birds calling.  Some of the sounds you are familiar with; a Black-hooded Antshrike, (Thamnophilus bridgesi), Bicolored Antbirds, (Gymnophythis leucaspis), and Chestnut-backed Antbirds, (Myrmeciza exul).  This seems as if it might provide some good photographic opportunities so you make sure the camera is ready with the correct settings.  Now some other birds fly past you and land on the tree trunks, most of them a variety of treecreepers; Streak-headed, (Lepidocolaptes souleyetii), Tawny-winged, (Dendrocincla anabatina), and Ruddy, (Dendrocinclo homochroa).  The bird calls are increasing in intensity, excitement and volume as you make your way to where they seem to be congregating.  As you approach you can see them briefy dropping from the vegetation to the ground and back up again.  There is another sound, a hum which pervades the air.  Having left your dreamlike state and become more acutely aware you see that you are surrounded by flies buzzing everywhere. You see one or two Gray-headed Tanagers, (Eucomectis penicillata), amongst the mixed bird flock, the presence of which along with the flies provide the clues as to what is happening.   Finally you hear, a sound like softly falling rain and yet there is not a cloud in the sky.  From about 5 meters in front of you and advancing rapidly towards you like a sheet of black polythene being pulled across the forest floor is a foraging front of Army Ants, (Echiton burchellii); a living wave of black death.

Rainforest ants. Hymenoptera. Formicidae. Dorylinae. Eciton burchellii. Army Ant. Costa Rica. Philip Davison. Veridion Adventures.

Army Ant, (Eciton burchellii), on the march

The feet of thousands of miniature assassins moving as one across the dried leaves give the illusion of rain falling.  You stand dumbstruck by the scene playing out in front of you.  As the procession of annihilation moves closer you can see down by your feet beetles, cockroaches and crickets running for their lives.  These are the lucky few.  The killers are insatiable.  Any small creature unfortunate enough to caught in their unrelenting path will be overwhelmed, stung to death, and then decapitated, dismembered and disemboweled.  The wickedly sharp mandibles of the army ant hunters slash and cut through exoskeleton, muscle and connective tissue.  The victim’s mutilated body fragments are then carried away by the mindless insect ghouls to provide a feast macabre for the larvae.  As fascinating to witness as this bloodbath at the macro level is, you had better move.  The ants are now crossing the path all around your feet. You might be too big for them to tackle, but the long stinger and virulent toxin can cause a lot of pain.

Rainforest insects. Hymenoptera. Formicidae. Dorylinae. Eciton burchellii. Army Ant. Costa Rica. Philip Davison. Veridion Adventures.

Army Ants, (Eciton burchellii), carrying severed spider leg back to feed larvae

For those insects capable of flight and able to escape the ravaging mandibles of the ants, the danger is not over.  The birds were attracted to the ant swarm to take advantage of the free meal they provide by flushing insects from their hiding places.  Gray-headed Tanagers are obligative followers of the army ants.  Wherever they are, you will find the tanagers.  The flies are there for the same reason.  These are Coffin Flies, (Phoridae sp).  When an insect attempts to escape by taking flight, the parasitic phorid fly swoops in, lays an egg and flies out again.  The eggs will hatch and the grub will eat the victim.

Army Ants are one of the major predators in the forest.  They rank alongside Boa Constrictors, Harpy Eagles and Jaguars as one of the top of the food pyramid predators in the forest.  They are a nomadic ant and they have to be nomadic because being such a super-efficient predator, should they settle in any one area for any length of time, they would deplete it of all small forms of life very quickly.

They have 2 three week cycles; a nomadic stage when they move in a flowing column of ants, the queen travelling with them, until they find a new hunting ground.  They do not construct a nest, they make a bivouac, generally at the base of a tree, which is a huge ball of ants held together by the interlinking of legs. The queen moves to center and swells up.  She starts to lay approx. 60, 000 eggs per day.  When the eggs hatch and the larvae emerge, the emit a pheromone which elicits a hunting response from the other workers.  They then move through the forest in a front anything up to 60 feet, (20 meters), across and take all small forms of life in their path: insects, small frogs, small lizards, small snakes, fledgling birds, if it is there then they will have it.  Once it has been butchered into small pieces, these are taken back via feeder columns to the bivouac to feed the larvae.  When the larvae pupate, the hunting response is switched off and  they return to the nomadic stage making their way through the forest once again.

A New Assassin

Rainforest ants. Hymenoptera. Formicidae. Dorylinae. Nomamyrmex sp. Army Ant. Costa Rica. Philip Davison. Veridion Adventures

Army Ant, (Nomamyrmex sp) carrying pupa from Leaf-cutter Ant, (Atta cephalotes), nest

There are many species of Army Ant and the species described above is the most commonly found in the area Echiton burchellii.  Last week I found a species that I had never seen before.  As well as slaughtering prey items on the forest floor, army ants will also enter the nests of other ants and take out the eggs, larvae, pupae, workers and queen.  They one ant they fight shy of taking on are the Leaf-cutter Ants.  There may be several hundred thousand in an army ant colony, there can be up to 8 million in a leaf-cutter ant colony.  The soldier leaf-cutters are huge and equipped with razor sharp mandibles.  They are programmed to fight to the death.  The army ants would lose so many of their own numbers if they were to raid a leaf-cutter ant nest.  Even if they come across them on a trail they will not interfere with them.

Rainforest animals. Hymenoptera. Formicidae. Atta cephalotes. Leaf-cutter Ant. Philip Davison. Veridion Adventures.

Leaf-cutter Ant, (Atta cephalotes), soldier

It was to my surprise therefore when last week a watched for the first time an army ant raid on a leaf-cutter ant nest.  Luckily I had the camera in my hand and found a place to lie down and take photos.  On this occasion the leaf-cutters seemed to be helpless to stop the nest being ransacked.  When I downloaded the images and looked at the images I did not recognize the species at all.  Despite their distinctive flat, square heads, extensive searching produced no I.D.  Eventually I found one photo and some information.  The genus is Nomamyrmex and it contains two species.  I am not sure which one I had been watching but I was happy to have witnessed an event I had never seen before being carried out by an ant I had never seen before and had the photos to prove it.

Rainforest insects. Hymenoptera. Formicidae. Dorylinae. Nomamyrmex sp. Army Ant. Philip Davison. Veridion Adventures.

Army Ants, (Nomamyrmex sp), raiding Leaf-cutter Ant, (Atta cephalotes), nest

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

 

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Drops of Colored Poison on a Leafy Bed   Leave a comment


Felipe del Bosque Blog February 11th 2013

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The Patter of Tiny Feet

The dry conditions continue but with the bonus of some rain at night which is enough to keep things green.  That hint of dampness is enough to tempt the Halloween Crabs, (Gecarcinus quadratus), out from the dark dank tunnels in which they reside beneath the surface of the forest floor.  They may be land crabs but they breathe through gills which have to remain moist to function effectively, so even though they may have escaped the confines of their aquatic environs and adopted a terrestrial habit, they have not fully adapted to totally dry conditions.  It always remains something of a surprise for people who had never heard of land crabs, and consequently only associate these crustaceans with the rocky coastal shorelines, to find the forest floor crawling with them following a summer shower.

It is not only those creatures in possession of 10 legs that have been spurred into action; the six-legged life forms of the social kind have suddenly become more obvious by their untiring activities.  Leaf-cutter Ants, (Atta cephalotes), familiar to most visitors to Bosque del Cabo due to the mesmerizing lines of slightly wavering fragments of leaf being carried in what seems like a slow moving river of green through the lawns and across the forest floor, have caught a second wind.

Normally at the height of the dry season the Leaf-cutter Ants cease their assiduous cutting and carrying during the daylight hours and recommence once the sun has set.  The dry season in the south west of Costa Rica can quite often result in very little rain for five months of the year and sometimes none at all during February and March.  At this time of year, should the ants cut and carry leaf, the distance over which it has to be transported and the time required to do so can result in the leaf drying out.  If the leaf contains small quantities of toxic compounds, as it dries these may become more and more concentrated thereby constituting a lethal cocktail for the ant or the fungus grown on the leafy mulch that provides staple diet of the ants.  This time of year those leaves delivered to the nest that were tasted and recognized as being unsuitable by the quality control ants are brought back to the surface and dumped on top.  The further we go into the dry season, the higher these mounds of dried leaves will built up around the entrances of the nest.

Leaf-cutter Ant

Currently the waste disposal ants in the colonies seem to be hard at work too.  In many of the nests around the trails excavation has been taking place at a heightened level of activity.  If you were to walk the trails on a daily basis you would see the heaps of earth accumulating in ever increasingly sized mounds.  Take a closer look and you will see the ants whose allocated employment is to remove excavated earth and waste products from inside the nest and bring it to the outside.  Each one is carrying a fragment larger than her own head.  Where the waste tip issues from the side of a hill or bank you will see the friable piles tumbling down, in ant terms each mouthful the size of a boulder, to the base.

Feeding of the Ravenous Hordes

The leaf-cutters are not the only ants that have been stimulated into action over the past week or so.  At various points on several trails long columns of ants moving quickly, deliberately and determinedly have been seen.  These are army ants, (Echiton spp), one of the forests most formidable mini predators.  Army ants have no nest, they are nomadic.  They have to periodically change the location of their temporary headquarters due to the fact that being such a super efficient predator, were they to remain in any one area for a protracted period of time they would deplete the locality of all small forms of life.

They may be encountered in one of two phases of activity; translocation or foraging.  When on the move to a new hunting area the whole colony including the queen is on the march.  There appears to be an endless river of ants streaming across the forest floor, insects in fluid form.  The workers carry the immobile pupae like swaddling aliens in their mandibles.  When virgin territory is reached the army ants ball up, linking their legs together to form a living bivouac, generally somewhere in a sheltered spot such as a hollow log or under a large fallen branch.  The queen moves to the centre, swells up and starts to lay about 60,000 eggs a day.

When the first larvae emerge, they emit a pheromone which causes a change in the behavior of the other workers.  They are stimulated into a hunting response which results in the mustering of half a million murderous assassins swarming through the forest slaughtering all that find themselves so unfortunate to be in their path.  The ravenous hordes surge relentlessly across the forest floor, up trees and scouring every nook and cranny.  The foraging front can be anything up to 60 feet across and 3 feet in breadth.

Army Ant

The ant’s progress will be heralded by flocks of exciting birds gathering as if at a tickertape parade.  You will hear the calls of antbirds, ant-thrushes, antwrens, woodcreepers, woodpeckers and tinamous.  If ever you see Grey-headed Tanagers you will see army ants, they are obligative followers of the army ants.  None of the birds are here to eat the ants.  As the front moves forward so many creatures are flushed, fleeing for their lives only to meet their end in the bill of a hungry bird.

Even if they escape those two terminal hazards, a third gruesome fate may await.  Clouds of parasitic flies, Phorid flies are flying in droves at the head of the advancing front.  The hum of their countless buzzing wings can be heard in the air.  They fly in and lay an egg on any victim attempting to escape the melee of death beneath.  The fickle hand of fate has played them a cruel hand.  They may have escaped mandibles, bills and jaws but the insidious cargo they now carry will now become their executioner.  When the egg hatches the fly maggot will eat its victim alive.

The ants push forward, unrelenting in their pursuit of fresh meat.  Whatever they come across they have, spiders, scorpions, centipedes, beetles, cockroaches, crickets, small frogs, small lizards, small snakes and even fledgling birds, it matters little to the ants.  There is no hiding place; the only choice is to run.  Once found, the prey is overwhelmed in a seething mass of frenzied killers, the ant’s venom laden stingers plunging through the victim’s skin time and time again and within seconds it will have been done to death.  Then it will be butchered on the spot, the slashing mandibles of the ants acting like meat cleavers to dismember the cadaver.  The separate parts of its now mutilated corpse will be carried back along feeder columns from the foraging front to the bivouac to feed the hungry carnivorous larvae.  Once the larvae pupate, the hunting response is turned off and away they go nomadically through the forest until they reach new and rich killing fields from which they will steal the lives of countless unfortunate creatures now dwelling there in blissful ignorance of their rapidly approaching fate.

Swollen With Indignation

Snakes are never the easiest animal life form to find in the forest.  They are ever-present but tend to elude those who want to see them but ironically make an appearance for those who don’t.  As with everything else, once you overcome your aversion to these reptiles, then they become fascinating creatures evolutionarily modified for a unique legless life-style.

One reasonably common snake around the grounds of Bosque del Cabo is the Neotropical Bird-eating Snake, (Pseustes poecilonotus).  They can grow up to six feet or more in length, are a pale blue-grey in color with a yellow belly and quite often a dark head.  If approached they put on a defensive display that involves flattening the neck laterally and turning the head side on so that they look larger than they are.  They are also very snappy snakes and are inclined to readily strike out and bite if molested, a characteristic of both juveniles and adults alike.

Tropical Bird-eating Snake

As the common name suggests, the bird-eating snake feeds on chicks and eggs from nests.  The breeding success of many birds at Bosque is hampered by these lithe predators whose forked tongue allows them to locate the presence of prey very quickly.  Many times around the restaurant area where Cherrie’s Tanagers and House Wrens nest and raise their offspring, it is almost a certainty that before too long the bird-eaters will turn up.

Pseustes poecilonotus

This individual I happened across this week when returning to my cabin.  It was lying across the path and I could see it ahead so just stood and watched for a while.  Its tongue was flicking constantly in and out tasting the air for scent particles.  It moved very slowly its head face down intently following what seemed to be a trail across the ground.  Then it lifted its body and flattened its neck, still its tongue rapidly flicking to taste the air and leaf litter in front as if something was bothering it.  I could see no sign of other life.  It looked like its attention was going to be held in this area for a while so I fetched the camera, lowered myself to the ground and took some close ups of its head before letting it slowly slither off into the undergrowth.

Unexpected Visitors

As the forest is so full of life it is no surprise that things turn up all over the place all of the time.  If I was to sit on the patio of my cabin and take time to look around I will see a myriad of small animals each one of which can capture your attention and then hold you thrall to its actions which can be observed, noted and later analyzed.  It may produce nothing more than an air of idle curiosity but when you delve a little deeper then most subjects however large or small have a fascinating life history and natural biology.

Jumping Spider

This week I was sat reading in the shade and noticed a line of minute ants making their way up and down the outside wall of my abode.  They were little more than moving specks and in typical ant fashion were following in a fairly strict line in both directions.  There was nothing unusual in this per se and my attention was concentrated more on where they were coming from and consequently where they were going to before returning again.

Saltacidae

Off to one side of the ant column was another small dark speck that I could make out as having eight legs.  Tiny as it was, its form and behavior suggested that of a jumping spider, Family Saltacidae.  As I sat watching a small drama unfolded.  One of the ants broke ranks and the maverick spirit took a line of its own deviating away from the main caravan.  This was to be its undoing.  Small prey attracts small predators; nature is red in tooth and claw at every size level.  This ant that had left behind the safety in numbers that comes with a being part of a group had now exposed itself as a target.  That error did not escape the attention of the spider.

Jumping Spider

Despite its minute dimensions, the jumping spider is an evolutionarily adapted hunting and killing machine.  Looking at it face on you will find the front of the head bears huge eyes which in spider terms are visually acute.  It’s not very often that the spider prey will see these eyes as the jumping spiders are as stealthy as a cat.  Once they have singled out their victim they sneak up on it at the last moment launch into the air landing on the hapless prey.  Needle sharp chelicerae inject a powerful immobilizing venom and digestive enzymes which both kill the prey as well as reducing its innards to a soup that the spider can suck from its now dead shell.

That is what happened to the ant.  It would not have even registered that anything was happening.  The attack was lightning fast.  The ant did not know what hit it and it was dispatched in the blink of an eye.  The tragedy played out on the mini stage before me was one of countless such encounters that you can witness all around if you choose to redirect the focus of your attention.

Bat Sac

Despite their numbers, abundance and diversity bats are not always the easiest animals to find.  When you do find a bat, without having it in your hand it may not always be the easiest animal to identify to species level.  Costa Rica has a very diverse bat fauna, 111 species in total of which 80 species live on the Osa Peninsula.

Some bats are so distinctive though that their identity leaves little ambiguity as to what it is you are looking at, the Greater White-lined Bat, (Saccopteryx bilineata), falls into this category.  One morning while walking on the Zapatero Trail with a group of guests, we stopped to watch two bats flitting around between the giant buttresses of the tree.  They would settle momentarily then flit off again to land not so far away.  When they did land it was face down but with the head pushed out at almost a right angle to the body.  This is the characteristic poise of the Greater White-lined Bat.  After the tour had ended I headed back in the hope of getting some photographs.  My luck was in, the bats were still there.  They were not keen on my presence and kept moving but with a little perseverance I managed to capture several images.

Greater White-lined Sac-wnged Bat

The Greater White-lined Bat is one of the sac-winged bats belonging to the Family Emballonuridae.  They are insectivorous bats and are normally communal roosters having one male guarding a harem of one or more females.  Quite often there can be several roosts in close proximity.  They are called sac-winged bats as the male has a small pouched scent gland on the wing in front of the forearm.  This emits a smelly secretion which is used in both territorial and mating displays.  The male can be seen during the course of the day flying up and down in front of the females serenading them with releasing scent from his ‘sac’.

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

Localised Poison

There are two species of poison arrow frog to be found at Bosque del Cabo; the Black and Green Poison Arrow Frog, (Dendrobates auratus), and the Golfo Dulce Poison Arrow Frog, (Phyllobates vittatus).  Both are visually unique, both have different calls and they inhabit different habitats so there should be no confusion as to what you are looking at when you find one.

Black and Green Poison Arrow Frog

Currently on the forest floor behind the restaurant where the Creek Trail enters the forest the Black and Green Poison Arrow Frogs can be seen without little difficulty.  You just have to walk ten yards or so then stop and look down by your feet and invariably you will see at least one but often several hopping around.  They are not inclined to be shy either, quite often making their way across the open expanse of the cleared trail or jumping around on the leaf litter to the sides.  The Golfo Dulce Poison Arrow Frogs can be a little more difficult to locate.  They prefer damper habitat and can be found by the creek beds.

Both species have different calls.  The black and green has a high pitched trill which is produced in a very broken stuttering fashion.  The golfo dulce calls with a long unbroken trill.  At certain times of the year you can hear the golfo dulce constantly calling but that is not always going to lead you straight to them.  They are more retiring than their black and green relatives and usually call from under fallen leaves, hollow logs or small spaces in the banks.  Also due to their inherent ability with regards to ventriloquism they seem to be in a different location to where the calls are emanating from.

The poison arrow frogs are diurnal.  For a frog to be found hopping around on the forest floor during the light of day would normally make it an easy target for predators.  These frogs have evolved toxic skin secretions to protect them against predation.  But there is little point having a toxic skin secretion if the predators are not aware of it.  If the frog gets eaten it is too late for both the frog and the animal naïve enough to eat it.  The glowing colors that they sport make them stand out clearly against the background.  If something is so deliberately drawing attention to itself it is not inviting predators to dine on it but rather warning them off.  These are warning colors, aposematic coloration.

Golfo Dulce Poison Arrow Frog

The black and green secretes a lipophilic alkaloid skin toxin which if you get it on your skin can cause burning and itchiness of cuts and scrapes.  Woe betides you if you get it on any mucus membranes such as eyes, nose or mouth.  Put two of these frogs in a bag together and they will die.  The golfo dulce is the most poisonous of the Costa Rican poison arrow frogs.  The skin toxin is a batrachotoxin which poisons heart muscle causing a painful death.  Do not attempt to handle these frogs but by all means admire them for their toxic beauty.

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 0.04 ins.  Total Weekly Rainfall 0.29 ins

Average Daily Rainfall 1.1 mm.  Total Weekly Rainfall 7.4 mm

Highest Daily Temp 96°F.  Lowest Daily Temp 75°F.

Highest Daily Temp 35.9°C.  Lowest Daily Temp 24.8°C.

Species List for the Week

Mammals

  • Mantled Howler Monkey
  • Spider Monkey
  • White-faced Monkey
  • Agouti
  • Alfaro’s Pygmy Squirrel
  • Red-tailed Squirrel
  • Greater White-lined Bat
  • Collared Peccary

Birds

  • Crimson-fronted Parakeet
  • Red-lored Amazon
  • Scarlet Macaw
  • Great Curassow
  • Crested Caracara
  • Mangrove Black Hawk
  • Roadside Hawk
  • White Hawk
  • Crested Owl
  • Spectacled Owl
  • Chestnut-backed Antbird
  • Short-billed Pigeon
  • White-tipped Dove
  • Blue-crowned Motmot
  • Rufus Piha
  • Long-billed Hermit
  • Red-capped Manakin
  • Chestnut-mandibled Toucan
  • Grey-headed Tanager
  • Bright-rumped Atilla
  • Dusky-capped Flycatcher
  • Black-throated Trogon
  • Great Tinamou
  • House Wren
  • Black Vulture
  • Turkey Vulture

Reptiles

  • Barred Ameiva
  • Cat-eyed Snake
  • Central American Smooth Gecko
  • Central American Whiptail
  • Clawless Gecko
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Mediterranean House Gecko
  • Pug-nosed Anole
  • Tropical Bird-eating Snake

Amphibians

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

Butterflies

  • Anartia Fatima
  • Anartia jatrophae
  • Archaeoprepona demophon
  • Caligo eurilochus
  • Colobura dirce
  • Dryas iulia
  • Eueides aliphera
  • Eueides lybia
  • Eurema albula
  • Glutophrissa drusilla
  • Heliconius erato
  • Heliconius hecale
  • Heliconius ismenius
  • Heliconius sapho
  • Heraclides cresphontes
  • Hermeuptychia hermes
  • Morpho helenor
  • Morpho Menelaus
  • Parides erithalion
  • Pierella helvina
  • Pierella luna
  • Pierella argante
  • Phoebis sennae
  • Philaethria dido
  • Pyrisitia proterpia
  • Pyrrhogyra crameri
  • Temenis laothoe

Plants

  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Apeiba tibourbou Flowering
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Attalea rostrata Fruiting
  • Bauhinia variegata Flowering
  • Cascabella thevetia Flowering and Fruiting
  • Citrus spp  Fruiting
  • Clusia rosea Flowering and Fruiting
  • Clusia vallerii Flowering and 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
  • Jacaranda mimosifolia Flowering
  • Heliconia chartacea Flowering
  • Heliconia latispatha Flowering
  • Heliconia pogonantha Flowering
  • Heliconia psittacorum Flowering
  • Heliconia rostrata Flowering
  • Hibiscus rosa-sinensis Flowering
  • Hymenaea coubaril Fruiting
  • Hymenocallis littoralis Flowering
  • Ixora coccinea Flowering
  • Lantana camara Flowering and Flowering
  • Lagerstroemia speciosa Fruiting
  • Morinda citrifolia Fruiting
  • Musa acuminate Flowering and Fruiting
  • Nephelium lappaceum Fruiting
  • Piper auritum Flowering and Fruiting
  • Piper nigrum Fruiting
  • Piper umbellatum Flowering and Fruiting
  • Pleiostachya pruinosa Flowering
  • Plumeria rubra Flowering
  • Psychotria sp Fruiting
  • Stachytarpheta frantzii Flowering
  • Virola guatemalena Fruiting
  • Zammia sp Flowering

 

 

Small Balls of Fire   Leave a comment


Felipe del Bosque Blog June 4th  2012

Flash & Crash

The week started bright and sunny but after a few days the heat built up, the hot moist air rose, condensed in the upper atmosphere and those thunderstorms so typical at this time of year arrived.  Here the storms pass overhead more often than not, bringing with them spectacular lightning shows, thunder that rattles all the buildings down to the foundations and of course the inevitable torrential rain.

The bosque creek still is running very low, but it won’t take too many of these downpours to fill it up.  The ground, which for the time being is soft and sticky, will soon become wet and cloying.

Dripping New Life

Now that it has been wet for a month or so, conditions that have encouraged the male amphibians to be out calling, the females having joined them and we are starting to see lots of eggs.  The Red-eyed Green Tree Frogs, (Agalychnis callidryas), have been laying their eggs in small masses under the leaves overhanging the pond.  The Smokey Jungle Frogs, (Leptodactylus savegei), are foam nesters and their distinctive egg containing frothy masses can be seen around the pond.  The smaller Banana Frogs, (Dendropsophus ebrecattus), lay their eggs on the vegetation floating on the pond surface.

All 3 of the above species have initially taken their eggs out of the water to develop away from aquatic predators.  With each, the eggs develop until about a week, then the larvae will drop into the water where they have to undergo a tadpole stage before metamorphosing into a terrestrial or arboreal frog.

The Leaf-cutter Ants have now been stimulated into 24 hour action on all of the trails.  During the dry season they normally work at night, away from the drying effects of the sun and high temperatures that could possibly desiccate the piece of leaf they are carrying over such long distances thereby rendering all that hard work to useless.  Now, with a change in the humidity it is possible to cut and carry all day and all night.

Stop and You’re Dead

Over the past week it has not just been the Leaf-cutter Ants making their presence obvious; the Army Ants have been out in force too.  Their unmistakable foraging columns can be seen traversing the forest floor, a living river of ants moving with unswerving purpose.

If you are lucky you may see the foraging front that the columns are serving.  This is a relentless forward marching line of ants up to 60 feet across and 10 feet or so in depth.  It is the phase in the recurring cycle of Army Ant activity where they move through the forest killing, dismembering and transporting any unfortunate small creature too slow to escape their advancing numbers.

You will be alerted to the presence of the murderous hymenopterans by the excited activity of so many birds; Antbirds, Antpittas, Ant Wrens, Ant Shrikes, Ant-tanagers, Ant Thrushes, Ant Vireos, woodpeckers, woodcreepers, tinamous and the ever present followers of the Army Ants, the Grey-headed Tanagers.  These birds are here, not to feed on the ants, but to take advantage of the easy meal afforded them by the frantic efforts of the insects to escape the jaws of the ravenous hordes.

There will be a hum in the air near the front of the seething black mass of ants; this is the sound of parasitic Phorid flies that are in the vicinity for the same reason as the birds.  As insects are flushed from their hiding spots, in go the flies, lay an egg on them and then retreat post haste.

The ants return with the mutilated remains of recently dead prey to a bivouac, a massive ball of ants that provide temporary accommodation for the colony by linking together their legs to construct a nest of living bodies.  This shelters the queen and the larvae while they feed and grow.  As soon as they pupate, the bivouac deconstructs and the ants then enter their nomadic phase, moving through the forest until they arrive at new killing fields to start the carnage once again.

All mammal life is as normal with many daily sightings of Howler, Spider, Capuchin and Squirrel Monkeys.  Solitary male White-nosed Coatis can commonly be seen around the grounds of the lodge while out in the forest, large groups of females in attendance of their large litters of offspring have been seen, particularly on the Titi Trail.  Agoutis too have been seen walking around with young ones, which have now left the shelter of the dens, in close proximity.

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

 Ball of Fire

Paper Wasp Nest         Paper Wasp Nest         Paper Wasp Nest

I you look under the leaves of many of the plants around the grounds you will see suspended structures that vary in shape from globular to cylindrical with various forms in between.  These are the nests of the paper wasps.

Paper Wasp Nest

The shape of the nest tends to be unique to the species of wasp making it.  The nests are made from carton which is chewed up plant material, normally wood.  Sometimes the wasps can be seen around the bar and restaurant area scraping away the surface layer of wooden rails with their mandibles.  They chew it into a pulp from which they make the paper that gives them their names.  They pulp is deposited layer upon layer to build the nest which houses the combs that constitute the brood chambers for the eggs and subsequently the developing larvae.  The nest may vary in color depending upon the source of the original construction material.  Some nests may be adorned with decorative features such as hanging flanges.

Polybia sp         Polybia sp         Polybia sp

Wasps are carnivores and feed on a wide variety of small arthropod prey.  The paper wasps generally belong to the genus Polybia.  Depending upon species they range in size from about 1.5 inches to .25 of an inch.  They are generally dark in color but banded with yellow.  They don’t use the sting to kill prey, which they do with the mandibles.  The sting is used for defensive purposes and to that effect contains chemical agents guaranteed to cause maximum pain.  They may be small but they are pugnacious and will defend the nest with vigor.   To that effect it is probably better to view them from a distance rather than close up.

Polybia sp

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 0.37 ins.  Total Weekly Rainfall 2.59 ins

Average Daily Rainfall 9.4 mm.  Total Weekly Rainfall 65.8 mm

Highest Daily Temp 90°F.  Lowest Daily Temp 75°F.

Highest Daily Temp 32.2°C.  Lowest Daily Temp 24.2°C.

 

Species List for the Week

Mammals

  • Howler Monkey
  • Spider Monkey
  • White-faced Monkey
  • White-nosed Coati
  • Common Opossum
  • Agouti
  • Red-tailed Squirrel

 

Birds

 

  • Orange-cheeked Parakeets
  • Scarlet Macaws
  • Red-lored Amazons
  • Crested Caracara
  • Pale-billed Woodpecker
  • Grey-necked Woodrail
  • Lineated Woodpecker
  • Chestnut-backed Antbird
  • Black-hooded Antshrike
  • Common Paureque
  • Short-billed Pigeon
  • White-tipped Dove
  • Long-billed Hermit
  • Rufus-tailed Hummingbird
  • Blue-crowned Manakin
  • Red-capped Manakin
  • Chestnut-mandibled Toucan
  • Blue-crowned Motmot
  • Long-tailed Woodcreeper
  • Banaquit
  • Cherrie’s Tanager
  • Golden-hooded Tanager
  • Green Honeycreeper
  • Red-legged Honeycreeper
  • Bright-rumped Atilla
  • Golden-crowned Spadebill
  • Great Kiskadee
  • Great Tinamou
  • House Wren
  • Black-throated Trogon
  • Masked Tityra
  • Black Vulture
  • Turkey Vulture

 

Reptiles

 

  • Central American Whiptail
  • Central American Smooth Gecko
  • Clawless Gecko
  • Common Basilisk
  • Five-lined Ameiva
  • Golfo Dulce Anolis
  • Mediterranean House Gecko
  • Norops limifrons
  • Northern Cat-eyed Snake
  • Salmon-bellied Racer
  • Tropical Bird-eating Snake

 

Amphibians

 

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

 

Butterflies

 

  • Anartia Fatima
  • Arawacus lincoides
  • Archaeoprepona demophon
  • Ascia monuste
  • Autochton neis
  • Battus belus
  • Caligo eurilochus
  • Cupido comyntas
  • Eueides lybia
  • Eurema albula
  • Glutophrissa Drusilla
  • Heliconius cydno
  • Heliconius erato
  • Heliconius hecale
  • Heliconius ismenius
  • Heliconius sapho
  • Heraclides cresphontes
  • Hermeuptychia hermes
  • Marpesia berania
  • Mechanitis polymnia
  • Morpho helenor
  • Morpho Menelaus
  • Pareuptychia occirhoe
  • Perophthalma lassus
  • Philaetria dido
  • Phoebis sennae
  • Siproeta stelenes
  • Taygetis andromeda
  • Turesis basta
  • Urbanus simplicius
  • Urbanus tanna

 

Plants

 

  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Anthurium salvinii Flowering
  • Apeiba tibourbou Flowering and Fruiting
  • Arachis pintoi Flowering
  • Aristolochia Fruiting
  • Arundina graminifolia Flowering
  • Astrocaryum standelyarum Fruiting
  • Atrocarpus heterophyllus Fruiting
  • Averrhoa carambola Fruiting
  • Brassavola nodosa Flowering
  • Brownea macrophylla Flowering
  • Calathea lutea Flowering
  • Callistemon viminalis Flowering
  • Cascabella thevetia Flowering
  • Chamaedorea costaricana Fruiting
  • Cocos nucifera Fruiting
  • Crestentia alata flowering and Fruiting
  • Clusia rosea Fruiting
  • Clusia valerii Fruiting
  • Costus speciosus Flowering
  • Couroupita guianensis Flowering and Fruiting
  • Eichhornia crassipes Flowering
  • Ficus insipida Fruiting
  • Garcinia madruno Fruiting
  • Genipa Americana Flowering
  • 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
  • Lacmellea panamensis Fruiting
  • Lantana camara Flowering
  • Lagerstroemia speciosa Flowering
  • Mangifera indica Fruiting
  • Miconia argentia Flowering
  • Morinda citrifolia Fruiting
  • Musa acuminate Fruiting
  • Naucleopsis ulei Fruiting
  • Pandanus tectonus Fruiting
  • Passiflora vitifolia Fruiting
  • Piper auritum Flowering and Fruiting
  • Piper umbellatum Flowering and Fruiting
  • Plumeria rubra Flowering
  • Psidium guajava Fruiting
  • Spathiphylum freidrichsthalii Flowering
  • Symphonia globulifera Fruiting
  • Terminalia catappa Flowering
  • Virola guatemalensis Fruiting
  • Virola koschnyi Fruiting
  • Vochysia ferruginea Fruiting

 

 

Bees Whose Bite is Worse Than Their Sting   Leave a comment


Felipe del Bosque Blog June 19th 2011

More of the Same

The weather continues to stay settled with bright, dry days and a little rain at night.  We are experiencing an occasional daytime shower but nothing like the torrential rains from the beginning of the rainy season.  Hopefully things will continue in this fashion until September when we will be expecting heavier rain of longer duration.

For the moment, all unstable vegetation seems to have already fallen.  That is not to say there will be no further tree falls over the coming months, but there have been no more large trees bite the dust, (that should be, wet forest floor), over the past week.

A team of experts were called in to cut up those unfortunate trees that were standing in the path of the giant Milky Tree that fell last week.  Even though the Milky Tree itself had little value in terms of lumber, the others did.  They were cut up in situ and the planking was then taken to be stored in the wood yard for future construction projects.

Counting By Numbers

People who study ants are known as myrmecologists and there are not too many of them.  Most of the visitors to the forests that encompass Bosque del Cabo did not realize before they arrived that they would be leaving having become enamored by the fascinating world of ants.  For those ant fans out there, at the moment, the ants are out in force.  During the dry season it is not always easy to view the flowing green rivers of freshly cut leaf being carried by none other than the Leaf-cutter Ants.  During the dry season they tend to work at transporting the leaf material back to the nest after the sun has set.  But now, when there is a break in the rain, any of the trails at Bosque will provide you with ample opportunity to marvel at this incredible spectacle.

Another type of ant, whose presence can be equally as obvious, is the Army Ant.  There are several different species of Army Ant in the area and to the untrained eye they may look to be one and the same.  Whether they are larger or smaller, they have the same characteristic habit of moving in a congested column and always with purpose.  Unlike the Leaf-cutter Ants which are mycovores, (fungus eaters), the Army Ants are strictly carnivores.  Over the past week, I have been able to show people the feeder columns heading back to the bivouac, (they don’t have an established nest, they are nomads).  With close scrutiny you can see a huge amount of dismembered arthropods being taken into the bivouac to feed the larvae.  On occasion we will happen across a foraging front over 60 feet across, moving across the forest floor and dispatching anything small enough that did not have time to move out of the way.

The Comfort Zone

On the site of the “Killer Wasp” attack from a few weeks ago, we now have a new resident, something a little more tranquil by nature, a female Long-billed Hummingbird.  She has chosen the underside of a leaf from a palm just to the side of the kitchen, behind the reception, to build her nest.  The nest is still under construction.  If you look closely you will see the strands of spider silk she has used to fix the nest to the leaf.  Following the addition of each new piece, the female then sits inside to try it out, with the bill facing the underside of the leaf.  She appears to be in a most uncomfortable looking position but it is how she will stay while incubating the eggs.  Hopefully I will get more photographs as the nest is completed.  There have been Long-billed Hummingbird nests in the same area, different leaves, in the past.  Their proximity to a busy human though fare does not appear to deter them.

Long-billed Hummingbird Nest

What Katydid

On one of the nightly “Sunset Tours” this week, I saw an unusual looking Katydid sitting on a leaf of the Calabash Trees.  There is nothing unusual about seeing an unusual looking Katydid as many of them display strange morphological characteristics.  There are a great many Katydids that have evolved to resemble various plant parts.  The Pseudoleaf Katydids in particular are intriguing creatures.  This one resembled nothing I had ever seen before.  The wings were raised up above its back which brought to mind the prehistoric Dimetrodon.  The color of the katydid was a mix of cryptic browns and grays that I can only imagine would blend in with the background color of the tree bark.

Katydid       Katydid       Katydid

Katydid

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

Blooming Orchids and Stingless Bees

Over recent weeks, while taking guests out on tour through the primary forest, I noticed an orchid that had been growing on the side of a tree for many years had started to produce flower buds.  This particular orchid had flowered every year and this year I kept a watch for bud development as I knew that the flowers would soon follow.  Over the course of a few days the flower buds lengthened and then on this day as I walked past, there were the flowers.  So after lunch it was back on the same trail with camera to get the images.

Stanhopea cirrhata

The orchid is a Tendril Stanhopea, (Stanhopea cirrhata).  It is a Neotropical orchid of which there are 55 species, 3 occurring in Costa Rica, but only one on the Osa Peninsula.  Stanhopea orchids are normally found in cooler climes, but Stanhopea cirrhata prefers growing exactly where this one is; in tropical lowland wet forest, low down on a branch in a less sunny location and close to the creek.  The flowers occur as a pair and give off a very sweet fragrance which not surprisingly attracts in male Orchid Bees, which are the plants main pollinators.  When I arrived to take the photograph, there was an Orchid Bee hovering in front but it did not wait for me to capture its image for later identification.

Stanhopea cirrhata

There had been some other bees that I had taken a mental note to return and photograph on the same trail as the orchids.  A few weeks previous I saw a swarm of brilliant orange/yellow bees gathering on plant leaves, close to the ground, at the base of a Milky Tree.  Following their appearance, over the course a week or so, a long waxy tube started to form from a crevice in the tree.  The tube was reddy orange in color, and extended 6 inches or more horizontally from the tree trunk.  These were one of the species of Stingless Bees, (Tetragonisca angustula).  The color of the tube depends upon the type of flowers that the bees have visited.  Incorporated into the wax you may also find mud and plant fibres.

They may be stingless but they can certainly bite and hard too.  They are renowned for their tenacity, swarming on mass into the mouths, ears and nose of those who antagonized them.  Some species as they bite release caustic secretions which burn.

Stingless Bees

Before the introduction of the European Honey Bee, Stingless Bees were the main source of honey for the indigenous peoples of Costa Rica and many of them still prefer Stingless Bee honey.  The honey itself has been clinically proved to have an antibiotic property.  You have to be careful which bees you are using though as some of them make a honey poisonous to humans.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Temperature and Rainfall

Average Daily Temp High 83°F.  Average Daily Temp Low 74°F.

Average Daily Rainfall 0.33 ins.  Total Weekly Rainfall 2.28 ins

Average Daily Temp High 27.9°C.  Average Daily Temp Low 23.1°C.

Average Daily Rainfall 8.3 mm.  Total Weekly Rainfall 57.9 mm

Species List for the Week

Mammals

  • Howler Monkey
  • Spider Monkey
  • Capuchin Monkey
  • Red-tailed Squirrel
  • Agouti

Birds

  • Orange-chinned Parakeets
  • Red-lored Amazon
  • Scarlet Macaw
  • Great Currasow
  • Crested Caracara
  • Mangrove Black Hawk
  • Roadside Hawk
  • Yellow-headed Caracara
  • Common Paureque
  • Lineated Woodpecker
  • Black-hooded Antshrike
  • Chestnut-backed Antbird
  • Wedge-billed Woodcreeper
  • Short-billed Pigeon
  • White-tipped Dove
  • Rufus Piha
  • Rufus-tailed Hummingbird
  • Red-capped Manakin
  • Chestnut-mandibled Toucan
  • Great Tinamou
  • Little Tinamou
  • Bright-rumped Atilla
  • Masked Tityra
  • Black-throated Trogon
  • House Wren
  • Black Vulture
  • Turkey Vulture

Reptiles

  • Barred Ameiva
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Pug-nosed Anole
  • Clawless Gecko
  • Mediterranean House Gecko
  • Cat-eyed Snake
  • Litter Snake
  • Salmon-bellied Racer

Amphibians

  • Marine Toad
  • Red-eyed Green Tree Frog
  • Banana Frog
  • Masked Smilisca
  • Milky Frog
  • Small-headed Frog
  • Smokey Jungle Frog
  • Black and Green Poison Arrow Frog
  • Golfo Dulce Poison Arrow Frog
  • Fitzinger’s Rain Frog
  • Tink Frog

Butterflies

  • Adelpha cytherea
  • Caligo eurilochus
  • Chioides albofasciata
  • Colobura dirce
  • Corticea corticea
  • Cupido comyntas
  • Detritivora gynaea
  • Dryas iulia
  • Euphyes vestries
  • Eurybia lycisca
  • Heliconius cydno
  • Heliconius erato
  • Heliconius hecale
  • Heliconius ismenius
  • Heliconius sapho
  • Heraclides cresphontes
  • Hermeuptychia hermes
  • Junonia everete
  • Morpho helenor
  • Morpho menelaus
  • Pareuptychia ocirrhoe
  • Parides erithalion
  • Pierlla helvina
  • Pierella luna
  • Pseudolycaena damo
  • Pyrgus oileus
  • Pyrisitia nise
  • Siproeta stelenes
  • Urbanus simplicius

 Plants

  • Astrocaryum Palm Fruiting
  • Black Alligator Tree Flowering and Fruiting
  • Calabash flowering and fruiting
  • Cedrillo Fruiting
  • Clusia Vine Fruiting
  • Devil’s Little Hat Fruiting
  • Dinner on a Plate Fruiting
  • Monkey Comb Tree Flowering and Fruiting
  • Candlestick Plant Flowering and Flowering.
  • Cannonball Tree Flowering
  • Figs Fruiting
  • Inga Fruiting
  • May Tree Fruiting
  • Manglillo Fruiting
  • Nutmeg Fruiting
  • Royal Palm Fruiting
  • Santa Maria Flowering and Fruiting
  • Stanhopea Orchid Flowering
  • Stinky Toe Fruiting
  • Ylang ylang Flowering

ARMY ANTS: A LESSON IN COMPLEX RELATIONSHIPS   Leave a comment


Veridion Adventures. Philip Davison. Rainforest animals. Rainforest plants

Today was a day of sunshine and showers.  I had a tour in the morning and so off we went into the forest.  The group I had out had never been to Costa Rica and had never visited a rainforest.  They were keen to learn something about this amazing ecosystem.  All the paths on their Internet research had led then to one place, the Osa Peninsula.  So far the experience had proved to be over and above their expectations.

We were walking through the forest and I was explaining the complex web of interactions, the sum total of which comprise a rainforest.  Being in situ and having physical props to illustrate the intricate relationships that exist here always helps give people a better understanding and a means by which to remember it all.

As we rounded a bend and crossed a bridge over the creek, we were confronted by a frenzy of highly animated birds.  This was a large mixed flock of birds from many different families, genera and species.  There were birds everywhere, perched momentarily on the branches, clinging briefly to the trunks, flitting here and there, dropping to the ground and then up again, all of them calling excitedly.  This behavior indicated only one thing; Army Ants, (Echiton burchellii), were on the move.  As we walked up the slope, the heralds of an advancing Army Ant column were there to announce their presence; Grey-headed Tanagers, (Eucomectis penicillata).  Wherever there are Grey-headed Tanagers, you can almost guarantee there are Army Ants.   Sure enough there they were, thousands upon thousands of ants marching in determined fashion in a series of well defined columns, flowing like small rivers made up of living insects, their only goal, the harvesting of all small form of forest life as food for the colony.

These feeder columns will then spread out into a front sometimes 60 feet across.  Army Ants are one of the top of the pyramid predators in the forest; they rank alongside Jaguars, Pumas, Harpy Eagles and Boa Constrictors.  They are a nomadic ant, they have to be nomadic because being such a super efficient predator, if they were to settle into any one location for any length of time, they would very quickly deplete it of all forms of life; spiders, scorpions, centipedes, cockroaches, crickets, small frogs, small lizards, small snakes, fledgling birds, if it is there the ants will have it.  All the carved up remains of the prey is taken back to the ant bivouac to feed the larvae.

During the dry season if an Army Ant colony is moving through the forest as a front 60 foot across, you can hear it coming.  It sounds like light rain pattering on the dead leaves.  Advancing towards you will be a living wave of black death.  All the excited bird activity is not due to the birds feeding on the ants, but rather on the insects that are being scattered as they run for their lives.  There will be woodcreepers, woodpeckers, antbirds, antshrikes, antpittas and those obligative followers, the Grey-headed Tanagers.  If you stand on the path running by your feet you will have crickets, beetles and cockroaches all fleeing for their lives.  And that is what we were witnessing here and now in front of us.  We were in situ and having a live visual performance enacted for us to illustrate one of the intricate relationships that exist here. This is one experience I don’t think those visitors will forget.

Army Ants; A Lesson in Complex Relationships

Well if it is not bad enough trying to photograph snakes, you should try photographing ants.  Unless you find some on a tree trunk at eye level, you are going to be lying on the ground.  I use a ground stand that allows me to fix the ball head.  But it is not easy to see through the viewfinder so now I have to use a right angle view finder attachment.  I like to capture as much detail as I can so I need a good depth of field which means a tiny aperture, f/32.  Now I need a lot of light which is where those five flash units come in.  Taking photographs of the Leaf-cutter Ants or the Army Ants means lining yourself up with a moving column but because you are only 2 or 3 inches from the subject the field of view is going to very small.  So as an ant hurries past the front of the lens you have only got a microsecond to hit the shutter.  I normally just focus the camera on a point and hope the ant is the correct distance away.  Once everything is set up I sit back, try to gauge when the scurrying ant will be in shot and use the cable release to take the photo.  It all sounds very easy doesn’t it?  It is a very hit and miss affair.  For every half decent good photograph you get, there are probably many more that you have to commit to the discard pile.

Army Ant stand off

Army Ant stand off

Nest Raider

Nest Raiders

Army Ants are voracious predators.  They will enter the nests of other ants and sack it of everything; eggs, larvae, pupae, workers and queen.  The only ants they will not interfere with under any circumstances are Leaf-cutter Ants.  There may be 500.000 in an Army Ant colony and up to 8,000,000 in a Leaf-cutter Ant colony.  Anyone who has experienced the flesh carving abilities of a Leaf-cutter Ant soldier will testify to the fact that they are not something to mess around with.  The Army Ants would lose so many of their own numbers trying to raid a Leaf-Cutter Ant nest that they will give them a very wide birth, even if they come across them on the trails.  That was the situation here.  There was an injured Leaf-cutter Ant near the moving column of Army Ants but they would not attack it.  The super mini predators backed off and faced the one struggling individual but would not engage with it.

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

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