Archive for the ‘Rainforest animals’ Tag

ARMADILLOS: SUCCESS OF THE ANCIENTS   1 comment


Wildlife, nature, fauna and flora of Costa Rica.

Transition, that is what is occurring now.  The days remain largely sunny but the rain has started to increase in volume, intensity and duration at night.  The creek running through the area is always a good yardstick by which to measure how dry the ground is.  This year the creek never dried up and as of this week the flow is fast and the level high.  The small cascades along its course are looking very picturesque with the water tumbling from higher to lower levels into the plunge pools, babbling softly as it does so and sounding like playful water nymphs inviting you to join them and cool off in the heat of the day.  The water here is clean and crystal clear, its depth holds no latent or potential disease and the only animal life is the occasional sighting of a tropical crayfish hidden beneath a submerged rock, its bright blue body being visible to only those with the keenest eyes.

The Puma, (Puma concolor), has been seen again and its tracks could be found on several trails around the grounds.  The past week has also been a good one for seeing the Squirrel Monkeys which are normally a little more retiring living as they do in the thickets of secondary forest.  At the moment they have been making daily excursions in large numbers through the gardened areas.

The repetitive call of the Bright-rumped Atilla, (Attila spadiceus), had fallen silent for some months but once again they have started up and bursts of “Read it, read it, read it, read it” can be heard again echoing around the trails in the early morning.  The frog breeding season normally starts with the first rains in May and then by the end of July it is over.  Not this year.  Every evening, just after sunset, the various species of amphibian emerge en masse, the males begin to call for a mate and by next morning the vegetation on and around the pond is covered in frog’s eggs.

Armored Four Sight

It is dark in the forest.  You can’t see much.  Your flashlight illuminates the path in front of you but the beam does not penetrate very far into the blackness and it also casts deep shadows.  There is something moving in those shadows.  You stop and listen.  It is not something small.  You shine the flashlight in the direction of the movement, your eyes peering into the gloom.  You still can’t make out any shape but the sound of the creature advances ever closer.  It crashes forward a few feet then stops for a moment and then moves again.  You can start to see the dead leaves and fallen twigs moving.  Your heart is in your mouth, it is almost upon you.  Then silence.  It is suddenly aware of your presence and it has stopped, motionless, whatever it is probably eyeing you as a meal.  Then crash, it takes flight and rushes across the path in front of your feet.  No wonder it sounded like a small tank rumbling across the forest floor, it is a mini armored insect feeder, a Nine-banded Armadillo, (Dasypus novemcinctus).

Rainforest mammals. Armadillo. Mammalia. Xenathra. Dasypodidae. Dasypus novemcinctus.

Juvenile Nine-banded Armadillo, (Dasypus novemcinctus), grubbing for food

Armadillos rank alongside sloths as one of the mammals that people would like to see when they visit the forests of the Osa Peninsula.  They are not as readily found as the monkeys, agoutis or coatis but they are here and they do show up fairly frequently.  They are encountered more commonly at night but it is not unusual to see them trundling around on the ground during the day too.

Armadillos belong in the ancient mammalian order: Xenathra along with anteaters and sloths.  Nine-banded Armadillos have a large geographic distribution.  They are found from the Southern United States through Central America down into Argentina.  Between 4 – 2 million years ago when the southern part of Costa Rica and Panama rose out of the sea to form the land bridge between the North American and South American continents it provided a means by which terrestrial animals could move between the formerly separated land masses.  Many northern species moved south and survived.  Only three species moved north and survived; opossums, porcupines and the Nine-banded Armadillo. Nine-banded Armadillos have a large geographic distribution.  They are found from the Southern United States through Central America down into Argentina.

There is no mistaking an armadillo for any other type of creature.  The body is covered in a shell composed of bony plates within a keratinous horny skin.  The eyes and ears of an armadillo do not function too well.  The long snout provides an excellent sense of smell which is essential in the location of food.  The majority of the armadillo’s diet is insects.  It has powerful claws which it uses to grub up a variety of ant and termite species from the ground.  With the nose stuck in the dirt, an armadillo can hold its breath for upto 6 minutes while it feeds on a particularly good banquet.  Those claws also dig out burrows in which the armadillo lives.

Reproductively armadillos are very interesting.  The female armadillo can delay implantation of the fertilized egg into the uterine wall if the prevailing weather or feeding conditions are less than optimum for its survival.  The egg always divides into four which means that the female armadillo will give birth to four identical quads.

Last week as I headed out for a walk I saw four of these juvenile siblings snuffling their way through the lawn, heads stuck in the ground, turning over the earth in search of a meal.  They had absolutely no idea I was there.  I took some photos and then lay on the ground to take some photos as they came trundling towards me.  It only dawned on them that I was there when one hit the camera.  The first defense response of an armadillo is to jump, albeit not too high, and then run off.  The first one to make contact with me turned and ran but the others still had no idea of my presence.  The adults are no better.  I have stood still in the past and had large armadillo running back and forth over my feet.  Should anything alarm them and they take flight, their short-term memory is little more than a few seconds before they return about their business as if nothing had happened.  I enjoyed watching these youngsters for a while before heading off and leaving them to feed and hopefully avoid coming across something that might not be as benevolent as I was.

All That Glisters

Down amongst the leaf litter a glitter of polished bronze slips under the leaves.  As it passes from beneath one leaf to the next you can see a metallic object glinting momentarily before disappearing again.  It moved too quickly to truly see what it was but you persist.  There it is again.  You bend down to move the leaf where it went, but nothing.  Then you see it just a hands breadth away.  A small head looking at you with intent dark eyes.  It is a lizard or more particularly a skink.  It is tiny with an elongated body and shiny smooth scales.  The scales catch the light and reflect a bright dark copper.  You find yourself looking at a Brown Forest Skink, (Sphenomorphus cherriei).

Rainforest lizards. Skinks. Reptilia. Squamata. Sauria. Scincidae. Sphenomorphus cherriei.

Brown Forest Skink, (Sphenomorphus cherriei), looking out from under a leaf

Several weeks ago I took photos of yet another small leaf litter dwelling lizard, the Northern Spectacled Lizard, (Leposoma southi), and stated that I really wanted to find and photograph the Brown Forest Skink too.  It is no easy task as they move quickly and once beneath the leaf litter ‘swim’ in a serpentine fashion through the decomposing vegetative material.  This one poked its head out long enough for me to get a quick shot or two.  I will have to keep looking to get the full body shot.

The hard and shiny scales of a skink may serve several purposes.  They help it glide between the material of the substrate making up the leaf litter in which it lives.  But there are lots of birds hopping around close to the forest floor whose keenly acute vision would spot a meal such as skink very quickly.  If caught in the bill of an avian predator the scales allow the skink to slip out and hopefully, as far as the skink is concerned, make its escape.

Rainforest Skink. Lizard. Reptilia. Squamata. Sauria. Scincidae. Sphenomorphus cherriei.

Brown Forest Skink, (Sphenomorphus cherriei), close up of head

Dressed In Black For The Telling Of Dark Tales

Walking on the forest trails you see a something take flight and then settle again on another plant.  The overall aspect is of an insect cloaked in funereal colors.  The body is black and the wings have black banding.  Nonetheless it draws your attention.

The creature is a Black-winged Dragonlet, (Erythrodiplax funeralis), a common dragonfly found inhabiting forest rides or at the edge of open areas.  Dragonflies are restless predators.  They are on the constant look out for a meal.  They are easily disturbed too.  Those huge eyes and mobile head can spot a potential predator or prey item very quickly.  If it is the former they fly to another perch.  The Black-winged Dragonlet has a much more fluttery flight than some other dragonflies which seem to dart back and forth.

They catch their prey on the wing which means they feed on flying insects.  Should a meal fly by the dragonfly swoops in and catches in its legs which form an open basket beneath the thorax.  The legs are covered in spines which make it difficult for the victim to escape.  Once ensnared, the prey will be dispatched, the hard body parts and the wings dumped to the ground and the rest of the body consumed.

Rainforest insects. Dragonflies. Odonata. Anisoptera. Libellulidae. Erythrodiplax funeralis.

Black-winged Dragonlet, (Erythrodiplax funeralis)

Dragonflies can present a challenge to photograph.  They are acutely visually aware, they move quickly and they don’t like being approached.  This one I had to follow, very slowly and patiently, before I managed to get a photograph.  It did take a good few attempts as it kept moving from perch to perch and I was on the point of giving up when it seemed to settle, at least long enough for me to hit the shutter several times.  Anyone out there who has tried photographing flying insects knows that patience is an essential virtue if you are going to obtain any images.

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

Spiders: The Eighth Level of Diversity   2 comments


Wildlife, nature, fauna and flora of Costa Rica.

The rainfall of April, May and June from 2016 was more or less exactly the same in terms of monthly totals for the same periods in 2107 but this week has proved to be very wet.  The rain has been incessant, both day and night with very little of the sun having been seen.  A total of 15 inches rain fell and now the creek is running quite fast, so no water problems this year.

Spiders:  Not Everyone’s Favorite

I have to admit that many people I take out would rather just walk straight past spiders and ignore their presence.  Some people, despite their revulsion, are intrigued by their natural history, they are, after all, fascinating creatures.  I find them interesting to observe, understand and photograph.  They are mini carnivores with a wealth of different life histories.  They are also ubiquitous, they can be found just about anywhere on the planet, (apart from maybe Antarctica), and in abundance.  It is often stated that at no point in your life are you any more than six feet away from a spider and I can demonstrate the proof of that fact quite adequately every evening when I take people on the night walk.

There are approximately 40,000 species of spider distributed worldwide which makes them the eighth most numerously named group of animals on the planet.  Although they are all, (apart from possibly one species), carnivores and use venom to subdue and kill their prey, they are not dangerous to humans expect for those well documented species, the numbers of which you could count on the fingers of your hands.

Spiders divide up into two broad groups.  The first group are the Tarantulas, Trapdoor Spiders, Funnel-web Spiders and the Purse-web Spiders.  The second group are all other spiders and they are subdivided depending of the mode of food capture.  There are the Web Weavers; those spiders that produce the familiar silken webs but those webs also come in different forms.  There are Orb-web weavers, Sheet-web Weavers, Tangle-web Weavers and Lace-web Weavers.  Then there are Ambush Spiders such as Crab Spiders as well as Wolf Spides, Huntsman Spiders, Lynx Spiders, Fishing Spiders, Spitting Spiders, Jumping Spiders, Woodlouse Hunters and Wandering Spiders.  All in all, if there is a way of catching prey, then spiders have it covered.

A Living Tetrahedron

I noticed this spider last week crossing the road in front of me.  The bright yellow coloration was in marked contrast to the grey grit across which it was scurrying.  As I bent down to take the photograph, the spider went into a defensive posture and tucked its legs up against the body.  This made it easy for me but gives it a somewhat unnatural pose.  I think this individual must have fallen from an overhanging tree branch, maybe escaping becoming a meal for a larger animal.  Being bright yellow might work to disguise it amongst foliage but not against the dark grey of the road surface.

Rainforest arachnid. Rainforest areneae. Costa Rica spider.

The strange tetrahedron shaped body of this unidentified spider

You can gauge how small the creature was by the size of the grit next to it which is only about 1mm across.  When looked at close-up though you can see the spider is remarkably shaped.  The body is drawn up into an almost polygonal shape, a tetrahedron, rounded along its edges.  There are raised red nodules along the rear edge.  You would think that these would make it an easy spider to identify, but no such luck.  Extensive searching has not provided an I.D.  I would hazard a guess that it is one of the many tropical orb-weavers.  If anyone has a name I would be very grateful to receive it.

A Silver Orb in the Sun

Further down the road, in an open sunny area I saw a large web with the weaver sitting in the center, its eight legs forming a cross of four pairs.  Because of its location I could not get around to the opposite side to get a dorsal view so had to settle for the ventral view.

This species I had seen before, on numerous occasions.  This was a Silver-orb Spider, (Argiope argentata).  The fluting of the body rim along with the black and yellow tiger striping of the legs are examples of disruptive form and coloration which serve to make the creature less spider-like.  It is an effective form of camouflage used throughout the animal kingdom.

Rainforest Silver-orb Spider. Rainforest animals. Argiope argentata Costa Rica. Spider web. Spider silk.

Ventral view of a Silver-orb Spider, (Argiope argentata)

The web itself is constructed from silken threads.  Silk is an amazing material and deserves a book devoted solely to that subject.  Silk is both elastic and strong.  Orb-weavers can produce upto five different kinds of silk, each variety having a different use.  Silk is produced as a liquid in the silk glands, it is then secreted from the spinnerets where it is drawn out by the hind legs into the long threads.

To construct the web, the spider first has to create a framework of threads radiating from the center.  Then starting on the outside, it spins a spiral thread, round and around towards the center.  The spiral silk is coated in a sticky hygroscopic glue which serves to catch any prey item unfortunate enough to fly or fall into it.  The elasticity of the threads takes out the kinetic energy of an impacting large flying insect and stops the web from breaking.  Silver-orb Spiders are fairly large and consequently so are their webs.  They are reasonably common in the area so it does not take too much effort to find them.

Hidden Death Dealer in the Flowerheads

Sometime ago I noticed a butterfly behaving in a very strange way on one of the Lantana flowerheads.  Further investigation revealed the butterfly was dead and the unusual movement was being caused by it being manipulated within the legs of a small but efficient killer, a Crab-spider.

Crab spiders are small squat spiders and receive their name due to their ability to walk sideways as well as forwards and backwards.  They are ambush predators.  Some have the capability of changing color over a period of weeks to match that of the flower where they are sitting and waiting for a prey item to land.  In this case the victim was a White-banded Fatima (Anartia fatima).

Rainforest Crab Spider. Unidentified Thomisidae sp Costa Rica.

Unidentified Crab Spider captures, kills and eats White-banded Fatima

The butterfly would have been totally unaware of the lethal assassin’s presence.  As soon as it landed to take a feed of nectar, the longer and stronger front two pairs of spider legs would have grabbed it.  The butterfly’s wings would have been beating frantically but taking flight was no longer possible.  At the same time, a powerful venom would have been injected through the spiders fangs into the butterfly’s body killing it almost immediately.  The spider holds on until the venom has done its work.  The wings stop beating and the now lifeless butterfly is motionless.  Digestive enzymes injected with the venom liquidize the butterfly’s innards which the spider will then suck out as a soup.  It will then let the dry and drained husk of the victim fall to the ground.

To find crab spiders you have to search diligently among the flower heads.  Sitting patiently without moving and having the same color as their ambush position makes them difficult to spot.  Sometimes the only clue to their presence is the telltale sign of strange behavioral anomalies of their victims.

Rainforest Crab spider. Thomisidae Costa Rica. Rainforest animals. Rainforest Spiders.

Death hidden by beauty. Crab Spider waits at tip of a flower for a meal to arrive

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