Stalking Big Cats and Alien Life Forms   3 comments

Felipe del Bosque Blog Sept 18 2010

Temp High 81°F  Low 74°F          Precipitation 0.84 ins

I had a slightly earlier start than normal today.  Once again the sky was grey and it seemed as if there was little promise of change.  As I was walking back from the workers canteen, in the soft ground I noticed a large deep footprint that had been made last night.  Under the cover of darkness a large feline visitor had been skulking around the confines of the lodge.  This was a large print, over 10 cm across.  It was actually the size of the print that initially caught my eye but also, although the ground was soft, it was not that soft and this was a deep impression, so whatever made it had to have been pretty large.  We only have two cats that size here, Pumas and Jaguars.  Puma prints tend to have oval, bean shaped toes, but these had round toes, indicative of a Jaguar, which would be in line with the size and weight.  I sent the photograph to Aida and Ricardo, the wildcat researchs, to see if they could confirm whether it had been a Jaguar on site last night.  I am awaiting their reply.

Jaguar Paw Print?

Not long after the discovery of the print, down came the rain.  It bucketed down all morning and so the evidence of the Jaguar has been erased, washed away, confined only to digital imagery.  The rain stopped me getting out to much too, although I did manage a quick walk around the grounds.  The only real thing of note was watching the mating display of two butterflies.  It wasn’t just been the frogs that were reproducing.  The behavior of two bright orange and black longwings, Heliconius ismenius caught my attention.  A female was sitting with her wings spread wide on top of a broad Costa leaf.  Above her a male was fluttering frenetically up and down, his wings a blur of motion.  The male butterflies has scent producing areas on his wings called androconial patches.  As he frantically flutters his wings tiny scales bearing sex pheromone break off and rain down on the female as microscopic “sex bombs”.  She is quite literally being showered with “love dust”.  For this particular male though, despite all his efforts and sweet talk, it wasn’t working, the female persisted in keeping her abdomen raised, which is a sign of “not interested” and if that wasn’t enough  to emphasize her lack of enthusiasm she would simply fly away.  But as with many an amorous suitor, he was not taking no for an answer and continued to press his unrequited energies, continually to no avail.

Heliconius ismenius Courtship

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.

Photo Feature

With all the excitement of last night’s new frog record, I decided to go out and photograph some of the eggs that had been laid around the pond area.  There are a whole variety of niches the frogs utilize to lay their eggs both in order to avoid competition and reduce the rate of predation.  These can range from fully aquatic to totally terrestrial and everything in between.

At the Bosque pond, there are two species that lay their eggs in the water, the Marine Toad and the Masked Smilisca.  The Marine Toad eggs are laid in long gelatinous strand, wound around the aquatic plant root systems like a double string of small black pearls.  The paradox is that Marine Toads are one of the largest amphibians in Costa Rica but they have some of the smallest tadpoles.  Marine Toads females can lay as many as 12,000 eggs.  The Masked Smilisca is another amphibian that reproduces in the water, this time the female deposits up to 2.000 eggs which float as a gelatinous sheet on the surface of the water.

Masked Smilisca Eggs

Gladiator Frogs are puddle nesters, the male builds his own little pond at the side of a pool of water by constructing a ring of mud.  He calls for a female, they spawn and 2.000 – 3,000 eggs again float on top of the water.  A rival male may try to enter his mud puddle nest, break the surface tension of the water which will cause the eggs to sink and drown them.  The male Gladiator Frog shows some parental care of the eggs as he will fight any interloper.  Using a bony spur on his wrist he tries to force it into the eyeball or eardrum of his adversary, blinding, deafening or even killing him.

Moving out of the water to lay their eggs are the Smokey-jungle Frogs.  These are foam nesters.  After mating and spawning, the male whips the 1,000 eggs up with mucus from his body and water from the pond which produces a creamy white froth.  The eggs develop within the froth until about 8 days after which the froth dissipates and the tadpoles as they now are enter the water where they have to complete the aquatic stage of their amphibious life cycle.

Slightly further away from the water surface we find the Banana Frogs.  As the sun sets, the males emerge, set up their territories on the leaves of floating Water Lettuce or Water Hyacinth and start to call.  The females come out later, they are much bigger than the males, the female frogs hold a lot of eggs so tend be bigger in body size.  They pair up and the female will now lay a clump of up to 250 eggs on the floating vegetation.  Once again, the eggs develop until about 8 days, the egg mass liquidizes, slips off the leaf, into the water and the tadpole has to complete that aquatic stage.

Yet higher in the vegetation we have two species of Red-eyed Green Treefrog.  The Red-eyed Green Treefrog is around the pond every night of the year.  You can hear its “Chuck, Chuck” call coming from the tops of the trees whenever you go out for a walk once the sun has set.  As with most amphibians they are present in greater numbers in the wet season rather than the dry season.  But there is the possibility of finding their eggs throughout the year.  The eggs are laid in clumps of about 100 on the underside of leaves overhanging the pond.  They develop to about 8 days and just as the Banana Frog eggs, liquidize and slip off the leaf, the tadpoles once more entering the water.

Red-eyed Green Treefrog Eggs

Parachuting Red-eyed Green Treefrog

The Parachuting Red-eyed Green Treefrog however is an explosive breeder stimulated to come out in huge numbers following bouts of torrential rain  Again they lay their eggs above the water but this time in sheets covering the upper surface of leaves from where they will slip off into the water after that 8 days of development.

Parachuting Red-eyed Green Treefrog Eggs

Now we have the more terrestrial frogs, those that don’t spend a lot of their time around water.  The Black and Green Poison Arrow Frog lives on the forest floor.  The females tend to approach the males and announce their willingness to mate by bumping into the chosen father of her offspring.  They mate and the female disappears leaving the male to watch over about 10 eggs that have been laid in the leaf litter.  When the tadpoles emerge, the male places them on his back, climbs the nearest tree and deposits them in a small pool of water somewhere high above the ground, possibly in the crevice of a branch or held within the centre of an epiphytic bromeliad.  Each male may be caring for the eggs of about 6 different females at any one time.

The Rainfrogs are small, totally terrestrial frogs; they don’t go back to the water to breed.  They pair up and similarly to the Poison Arrow Frogs, lay their eggs in the leaf litter.  There are only about 30 eggs, fairly large in size compared to the size of the frogs.  The whole process of development takes place within the egg; there is no free swimming tadpole stage.  After about 4 months, a tiny little copy of the adult emerges.

From the above you can see there is a progressive move away from totally aquatic to what is ultimately a totally terrestrial breeding behavior.  Along with this shift away from the water there is a corresponding reduction in the number of eggs produced from the 12,000 of the Marine Toad to the 30 eggs of the Rainfrogs suggesting the highest rate of predation on the tadpoles may be in the water itself.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Species List for the Day


Howler Monkey

Spider Monkey


Grey-four Eyed Opossum


Red-lored Amazon

Mealy Amazon

Scarlet Macaw

Pale-billed Woodpecker

Bright-rumped Atilla

Southern Beardless Tyrannulet

Grey-necked Wood-Rail

White-tipped Dove

Chestnut-backed Antbirds

Black-hooded Antshrike

Blue-crowned Manakin

Fiery-billed Aracari

Chestnut-mandibled Toucan

Cherrie’s Tanager

Mourning Warbler

Yellow-headed Caracara

Roadside Hawk

Great Tinamou

Black Vulture




Tink Frog

Fitzinger’s Rainfrog


Heliconius erato

Heliconius hecale

Heliconius ismenius

Heliconius sapho

Heraclides cresphontes

Hermeuptychia hermes


Posted September 19, 2010 by felipedelbosque in Philip's Nature Diary

3 responses to “Stalking Big Cats and Alien Life Forms

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  1. Soooooo was it the BIG J??


  2. Phillip,

    It is unusual for the J. to be that close to the lodge? Has anyone seen it that close before?

    Great pics of all the frogs. My Calif. grandchildren are really enjoying all these blogs of yours, especially Jack, keep it up.


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