Little and Large   Leave a comment


Felipe del Bosque Blog Sept7 2010

Temp High 80°F  Low 72°F          Precipitation 0.4 ins

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.

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.

http://www.bosquedelcabo.com

Photo Feature

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

Smoky Jungle Frog

The Smoky Jungle Frog, (Leptodactylus pentadactylus), 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.

The Smoky Jungle 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.

Stejneger's Dirt Frog

Closely related to the huge Smoky Jungle Frog is probably one of the smallest frogs in Costa Rica, the tiny Stejneger’s Dirt Frog.  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.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Species List for the Day

Mammals

Howler Monkey

Spider Monkey

Capuchin Monkey

Agouti

White-nosed Coati

Red-tailed Squirrel

Birds

Red-lored Amazon

Great Currasow

Bright-rumped Atilla

Chestnut-backed Antbirds

Black-hooded Antshrike

Red-capped Manakin

Chestnut-mandibled Toucan

Green Honeycreeper

Cherries Tanager

Golden-hooded Tanager

House Wren

Streak-headed Woodcreeper

Tennessee Warbler

Roadside Hawk

Black Vulture

Reptiles

Basilisk

Four-lined Ameiva

Pug-nosed Anolis

Golfo Dulce Anolis

Mediterranean House Gecko

Northern Cat-eyed Snake

Amphibians

Marine Toad

Red-eyed Green Treefrog

Banana Frog

Smokey Jungle Frog

Tink Frog

Fitzinger’s Rainfrog

Stejneger’s Dirt Frog

Black and Green Poison Dart Frog

Butterflies

Anartia famita

Dryas iulia

Eueides aliphera

Eueides lybia

Caligo eurilochus

Heliconius erato

Heliconius ismenius

Hermeuptychia hermes

Napaea eucharila

Phoebis agarithe

Phoebis sennae

Pierella luna

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Posted September 8, 2010 by felipedelbosque in Philip's Nature Diary

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