Archive for the ‘Craugastor stejnegerianus’ Tag

BEETLES: HIDING IN CLEAR VIEW   6 comments


Wildlife, nature, fauna and flora of Costa Rica.

It has been another week of sunny days and rainy nights.  Last month the immediate area experienced almost 28 inches, (706 mm), of rain.  That is approximately 1 inch per day.  However, as to be expected, the pattern of precipitation was not that evenly spread.  There were several nights with really heavy downpours which accounted for a third of the total.  There were more nights when it rained hard but not in a deluge and then there were nights when there was no rain.

Atop Cabo Matapalo, at 500 feet, (150 m), above sea level, there is little chance of flooding, all the water is runoff.  This time of year the ground is saturated so when there is a torrential downpour the water may remain on the surface forming large areas of standing water which quickly drains away.  The creek water level is high and rushes down the channels, falling over rapids, cascades and waterfalls and finally flowing into the sea.  After a night of very heavy rainfall, the creek will have turned murky brown with the volume of sediment it is carrying.  Given a few days of sun the water will have returned to its crystal-clear state, inviting you to plunge into its cooling depths as a relief from the hot and humid atmosphere of the forest.

A Typical Rainy Season Day In The Forest

You wake in the morning, opening your eyes but still not fully conscious.  You had a good night’s sleep, restful and undisturbed, but were brought out of your slumber by a distant roaring sound.  It is still dark outside so what time is it?  Early, pre-dawn, and the roar is heard again, this time joined seconds later by a response, louder roaring but much closer to your cabin.  All of a sudden the roars are echoing around the forest.  To many, the first-time visitors to a Central American rainforest, this could only be large ferocious beasts gathering to collectively do you harm.  To the more savvy, seasoned visitor this is a familiar wake-up alarm call, Howler Monkeys, announcing their location to one another so that different troops can keep their distance during the course of the day.

It did its job as far as you are concerned, you are now fully awake.  The first light of dawn starts to brighten the sky, throwing the form of the trees into dark silhouettes.  Here you are only 8⁰ north of the equator so the dawn twilight does not last for long.  The sun rises rapidly and the grey sky turns blue.  The birds are awake now.  Flying overhead are noisy macaws and parrots heading off from their roosts to the feeding grounds.  Their squawking and screeching is not the most melodious of avian calls.  From within the forest the Chestnut-backed Antbird, Black-hooded Antshrike and the Bright-rumped Atilla are some of the first choristers to greet the new day.   The males are vocally drawing up the bounds of their territories.

It is after breakfast and the sun is now high in the azure sky.  The temperatures have rapidly risen from the cool chill from when you opened your eyes.  The air is still.  You grab your camera and head off into the shade of the forest.  The only sound is that of cicadas, their loud calls increasing in intensity, volume and pitch as the morning progresses.  Here and there from different points in the unseen depths of the forest, obscured from your vision by the trunks of the trees are more birds calling.  The familiar “Who cooks for you” of the Short-billed pigeon, the high-pitched squeaky call of the Black-mandibled Toucan, it sounds more like a rusty pulley that needs oiling than the call of a bird.

You see many things close at hand to photograph, flowers, fruit, a beetle, a praying mantis, small frogs and lizards.  Up above you the Spider Monkeys put on an impressive display of acrobatics as they swing through the tree tops.  You can’t miss Spider Monkeys with their high-pitched chattering and high-energy crashing through the tree tops.  This is in complete contrast to the languid slow moving and deeply voiced Howler Monkeys.  You come across a troop of White-faced Monkeys, more leisurely in their pursuit of a meal.  You see them peeling away bark and turning leaves, always gleaning, looking for the small creatures that make up the bulk of their diet.

It is approaching midday.  The sun is directly overhead.  Despite being beneath the shade of the canopy, the temperatures have risen dramatically.  Combined with the high humidity, conditions have become like those in a well stoked sauna.  If the air was still outside the forest, within its confines there is not a breath of air.  The sweat is rolling down your face and your clothes are now soaked.  Thankfully you brought a lot of water with you and a packed lunch.  Time to take a break for some respite in order to recover you waning energy levels.

As you sit, taking in the sounds around you, a rumbling can be heard off in the distance, thunder.  You finish your sandwiches, take a swig of water, pack everything into your bag and head off down the trail once more.  You stop to photograph a line of Leaf-cutter Ants.  You need to get close to the ground and have some patience to capture the individual caste members.  You are rewarded a little later with a swarm of Army Ants, incessant in their drive forward flushing out non-flying arthropods.  They are accompanied by a mixed flock of ant-birds, woodpeckers, woodcreepers and Grey-headed Tanagers, all in a heightened state of excitement as they feed on the flying insects driven out of hiding by the Army Ant assassins.  Lots of photographic opportunities here.

It is now much later; the almost unbearable temperatures have dropped and the sun is sinking fast towards the western horizon.  Also, that rumbling is getting louder and the sky is rapidly darkening in the east.  You have filled your memory card with images so it may be astute to pick up the pace now and head back to base.  Before too long a breeze picks up and the tree crowns begin to sway.  Loose leaves and small twigs come tumbling down from the canopy.  It is rapidly darkening and the breeze becomes a wind.  The trees are now swaying more violently and you can hear branches being snapped and crashing down.  All of the monkeys start to shriek in objection to their homes being shaken in this manner.  The advancing storm has no ears and cares not for their protestations. Light rain begins to fall.

Within a shorter time than you would have liked, the sky above you has turned black.  The rumbling thunder has become loud and explosive, now accompanied by almost instantaneous flashes of lightning.  The rain comes out of the heavens with an ever-increasing intensity.  The canopy is being lashed.  Leaves and branches are torn from the trees by the sheer weight and force of the water being poured upon them.  Lightning is cracking and fissing around you, the storm is immediately overhead, these are thunderflashes and this is not a safe place to be.  The path at your feet which moments earlier was soft and damp is now a running river albeit only a couple of inches in depth.  The question is should you stop and find shelter or should you persevere on.  You chose the latter option.

Your step quickens, not too fast as you don’t want to slip and fall.  You hear a sharp crack above you, then a loud snap and a huge branch comes tumbling with force through the understory.  It hits the ground so hard that it stands upright as if it had been planted.  The flashes are lighting up the whole sky in a blinding white light.  Each boom of thunder causes you to flinch.  It is raining so heavily that you can barely open your eyes due to the stinging pain it causes you.  But you are almost there, the path out of the forest is up some stairs and around a bend on the trail.  The steps are now a series of cascades but the tumbling water does not hinder your stride.  You will soon be back in the dry comfort of your cabin.

Just as you step out of the forest and into the open garden area, the driving rain suddenly subsides to that of a light summer shower.  The black sky starts to lighten and the deep rumbles roll off into the distance.  Each flicker of lightning is still causing flashes but now over on the horizon.  Thankfully you had the foresight to pack all of your equipment into a waterproof camera bag before the deluge descended and it seems to have served its purpose well.  The rain becomes drizzle and finally peters out then stops.  The sky is now pale grey and the sun sinks to the point where the final rays light up the underside of the clouds in a deep orange.  You have just experienced a typical September day in a Costa Rican rainforest.

Beetles Hiding In Clear View

Beetles, there are thousands of species and yet if you go out with the intention of finding them you may become aware very quickly that they are not as obvious as you have thought.  Turning over rocks or peeling rotten bark from fallen trees may produce one or two species but nothing in profusion.  That is why when I head off into the forest it is never with the purpose of photographing anything specific, not unless I have seen something that I wanted to return to.  Some people go out having birds or mammals as their goal, I am always looking for smaller things, as regular readers of the blog will already know.  The camera will have my favorite 105mm macro lens attached and will be set to take photos of all manner of mini beasts in darker conditions.  The shots will be hand held as I only take the tripod if I have a certain subject in mind.

Last week I found two different species of beetle out in the open aspect of a sunny forest edge.  They were in separate locations but within the same area.  They were both sitting on top of a leaf, in bright sunshine and would not stay still.  I had to keep maneuvering around the subject to try and get a decent image.  Every time I had things set, they would turn their backs to me and wander off along the opposite length of the leaf.  Finally, after much repositioning, I managed to obtain some acceptable photographs.  One of the problems with photographing beetles is the hard, smooth and glossy exoskeleton that many of them have.  It reflects the light from the flash gun.  To obtain the depth of field that I prefer, with a moving subject I have to use very small apertures and by necessity I need to add extra light with flash.

The first beetle is a Pleasing Fungus Beetle, (Cypherotylus asperus), in the family: Erotylidae.  I am not sure why they are pleasing but fungus beetle refers to their main dietary item which may come as no surprise, fungus.  The bright red blotches against a black background is aposematic, or warning coloration.  If molested or attacked, the Pleasing Fungus Beetle emits a foul-smelling odor that would cause most would be predators to back off.

Rainforest animals. Rainforest insects. Rainforest Beetles. Coleoptera. Erotylidae. Cypherotylus asperus.

Pleasing Fungus Beetle, (Cypherotylus asperus)

The second beetle is a Leaf Beetle in the family: Chrysomelidae.  They typically have the domed body, clubbed antennae and are multi-colored.  But as there are almost 50,000 species in this family I have, so far, been stumped as to which species this is.  Should any beetle expert be reading this and would like to provide a name I would be most grateful.  The clue to the diet is once more in the name.  They feed on the leaves of a variety of vegetation.

Rainforest animals. Rainforest Insects. Beetles. Coleoptera. Chrysomelidae.

Leaf Beetle, (Chrysomelidae sp)

The Earth Moved

Walking through the forest you can often have your attention momentarily attracted by some small movement down in the leaf litter.  It may be ants, spiders, lizards, frogs or a myriad of other small creatures that live concealed beneath the carpet of rotting leaves.  It is the tread of your footfall that will disturb them and have them run for cover out of harm’s way.  Depending on the speed of the animal you may lose sight of it very quickly.  Some move from leaf to leaf.  Generally if any of these litter living denizens gets below the leaves it will be gone and unless you are lucky you will just have to imagine what you saw.  Occasionally though one will freeze when exposed to the light.  Last week, my size 13 boot thudding into the ground caused a tiny frog to jump out of the imminent descending disaster.

There are several small frogs that inhabit the dark and damp environment of the forest floor.  The squat body shape of this one revealed its identity almost immediately.  It was one of the rather delightfully named dirt frogs, this one being a Stejneger’s Dirt Frog, (Craugastor stejnegerianus).

Rainforest animals. Rainforest amphibians. Frogs. Anura. Craugastoridae. Craugastor stejnegerianus.

A tiny Stejneger’s Dirt Frog, (Craugastor stejnegerianus)

The dirt frogs are totally terrestrial frogs, they live their whole life on the forest floor and never need to go to water as many amphibians do.  They still have moist skins through which they largely breath and therefore by necessity can’t leave the confines of the damp environment under the trees.   There are several species that live in this area and Stejneger’s Dirt Frog is one of the commonest.

They belong to the family: Craugastoridae or the Fleshbelly Frogs.  Typical of this family is the reproductive habit of direct development which negates the necessity of them having to return to water to reproduce.  The frogs pair up, (I can’t say I have ever heard these frogs calling), and the female lays her eggs amongst the leaf litter on the forest floor.  There are only about 20 – 30 eggs but they are fairly large in comparison to the adults.  The egg is packed with yolk and the tadpole develops within the egg, there is no free-swimming tadpole stage.  After about 8 weeks a tiny copy of the adult emerges.

Rainforest animals. Rainforest amphibians. Rainforest Frogs. Anura. Craugastoridae. Craugastor stejnegerianus. Osa Peninsula. Costa Rica.

Dorsal view of Stejneger’s Dirt Frog, (Craugastor stejnegerianus)

As you are walking through the forest, if you keep your gaze lowered scanning the ground then you will surely see a small piece of the earth move.  Given closer inspection then you will probably find you are looking at a dirt frog.  But take a photograph as they are not always easy to identify.

Fying Dragons.

A few weeks ago I managed to photograph a dragonfly with black bases to the wings, a Black-winged Dragonlet, (Erythrodiplax funerea).  This week I managed to capture another dragonfly but with the inverse situation of having black tips to the wings, the Large Woodskimmer, (Uracis fastigiata).  This one was found in a different area to the previously mentioned species but they had been there for several weeks.  This species was found in secondary forest, in a light gap and always close to the ground.  Once again my attempts to take a picture were always doomed to failure because every time I lifted the camera to my eye, they would fly off.  But as we know with photography patience is a virtue and finally after several weeks I got lucky.  This one stayed still long enough for me to get several pictures.

Rainforest animals. Rainforest Insects. Dragonflies. Odonata. Libellulidae. Uracis fastigiata

Large Woodskimmer, (Uracis fatigiata)

Unlike the dragonflies which can be found in open sunny locations around a body of water that have fast flight and hover, these forest species seem to be more sedentary and perch on low vegetation and only seem to move if disturbed.  Having excellent eyesight adapted to detect movement it does not take much to disturb them.  It could be that they are sit and wait predators just diligently watching for the right sized meal to pass by before taking off to capture it.

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

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FROGS OF COSTA RICA: LARGEST AND SMALLEST   Leave a comment


 

Wildlife, nature, fauna and flora of Costa Rica.

The sun sets rapidly in the tropics; there is no real twilight or dusk to speak of.  Last night as the sun dipped below the horizon, the sky darkened and stars started to appear for the first time in weeks.  At this time, sitting low in the west but just above the level of the trees we are treated to the sight of Venus which is by far the brightest light in the currently moonless sky.  Venus is closely accompanied by Mars which is a little lower and has all but disappeared from view by the time it is dark.  As the evening progresses and Venus slips from view, another bright light will have risen in the east, Jupiter, which will make its way across the heavens to set before sunrise.  If the clouds permit, then the Milky Way is a phenomenal sight this time of year, arching like a translucent creamy smudge across the sky from north to south.

Today started as last night ended, not a cloud in the sky, and apart from a few scattered showers throughout the morning, that is how things stayed.  This time of year we have the daily dawn chorus of Chestnut-backed Antbirds, Black-hooded Antshrikes, Bright-rumped Atillas and the raucous din of the Scarlett Macaws.  All of this has, of course, been preceded by the early morning wakeup call provided by the Howler Monkeys.  The ruckus is normally complemented and completed by the arrival of large numbers of Red-lored Amazons, whose higher pitched squawking simply adds to the cacophony.

Walking through a rainforest after a shower certainly gives the overall impression of dampness.  It has been raining since April and so the creeks and rivulets in the forest have a constant supply of running water.  The ground is both soft and sticky under foot.  With the addition of a shower, the vegetation already dripping with moisture, now most certainly completes the visitors’ expectations of how a tropical rainforest should look.

After returning from the four hour “Primary Forest Tour” I went off to the staff canteen to get some lunch.  That was followed by a leisurely stroll around the grounds to see if any new birds and butterflies had turned up.  One did, a butterfly I had not seen before, and guess what; once again I was not carrying my camera.  Here in front of me on vegetation close to the ground was a very conspicuously patterned Metalmark.  These are small and generally insignificant butterflies, but here was one with a dark background with a concentric series of white dashes and a bright red border to the hind wing, a White-stitched Metalmark, (Napaea eucharila).  I ran over to my cabin to get the camera but when I returned, it was gone.  So, I have found two new species in one week and no images to prove it.  At least I have the images in my head and the records in my diary.

As I write, the sun is sinking one more time.  It is amazing how time flies when you are enjoying yourself.  It is a brilliant sunset, a blaze of bright red which is bathing the forest in a deep luminescent orange glow.  It is now time to head out and see what the evening brings.

Costa Rican Frogs: The Largest and the Smallest

Here we are looking at two extremes; one of the largest and one of the smallest frogs on the grounds of Bosque.

Rainforest amphibians. Frogs. Leptodactylidae. Leptodactylus savagei. Savage's Thin-fingered Frog. Felipe del Bosque. Veridion Avdentures.

Male Savage’t Thin-fingered Frog

Savage’s Thin-fingered Frog, (Leptodactylus savagei), is a veritable behemoth of a frog, second only in size to the female Marine Toad.  They are the only amphibian we know of that eats scorpions, but they are opportunistic feeders and will eat smaller frogs, snakes, really anything smaller than themselves.  Like the Marine Toad, it is very poisonous, having skin secretion called Leptodactylin.  If you handle the frog it is very uncomfortable, but if you then rub your eyes, nose or mouth, in fact any mucus membrane it can be become a very distressing situation.  They do have predators though, more or less the same predators as Marine Toads, i.e. Opossums and snakes.  To that effect they have a secondary defense.  When you catch one it will scream like a baby.  The screaming may shock the predator into letting it go or the commotion could attract the attention of any other predator in the area which subsequently may attack whatever is trying to eat the frog, but most importantly, the screams very closely resemble the alarm calls of young caiman.  If there any adult caiman in the area, they will charge in and attack the frog’s predator which will hopefully, as far as the frog is concerned, allow it to make its escape.

Savage’s Thin-fingered Frog is a foam nester.  The male comes to the water first.  He has massive front legs and gives emits a “Whoop, whoop” call.  The female joins him later, he grabs on to her with his massive front legs, he has two sharp spines on his chest which also help secure her until she is ready to lay eggs.  Once the female has spawned, the male fertilizes the egg mass and then using his hind legs he whips the eggs up with water from the pond and mucus from his body to produce froth.  The eggs develop in the froth until about 8 days at which point the froth dissipates and the tadpoles as they now are have to complete the normal tadpole stage in the water.

Rainforest amphibians. Frogs. Craugastoridae. Stejnegers Rain Frog. Craugastor stejnegerianus. Costa Rica. Philip Davison. Veridion Adventures.

Stejnegers Dirt Frog, (Craugastor stejnegerianus)

Closely related to the huge Savage’s Thin-fingered Frog is probably one of the smallest frogs in Costa Rica, the tiny Stejneger’s Dirt Frog, (Craugastor stejnegerianus).  These are tiny frogs that live terrestrially on the forest floor.  If you ever spot a slight movement down by your feet as you on the forest trails, close examination will quite often reveal a frog no bigger than your fingernail.

Stejneger’s Dirt Frog is one of the rainfrogs.  They do not need to come back to the water to breed.  They pair up and lay only 10 – 30 yolk filled eggs, fairly large in comparison to the frog, in the leaf litter on the forest floor.  The whole process of development takes place within the egg so there is no free swimming tadpole stage.  After about 8 weeks, you will find emerging from the egg a tiny copy of the adult.

So there you have it, the little and large of the amphibian world.

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

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