A New Season Starts   2 comments

Felipe del Bosque Blog Nov 21st 2011

Returning To More of The Same

I spent last month in the beautiful Nicaraguan colonial city of Granada.  During the period away I experienced very little by way of rain.  The dry Pacific coast of Central America provided 4 weeks of parched, sunny and hot, at times blisteringly hot, days.  In the evening the temperature dipped, but not by much, the night air was still very warm by temperate standards.

Following a month of these sweltering conditions, I had banished all thoughts of rain in a rainforest to the back of my mind but those suppressed short term memories were quickly brought back to the fore as I crossed the border from Nicaragua to Costa Rica.  Once more the skies were grey and the threat of a deluge loomed large on the southern horizon.  I didn’t have to wait long for that threat to be realized as the skies opened and down came the rain.

While only spending one night in San José, I was reminded of the difference between coastal living, whether it be wet or dry, and the totally different climatic regime experienced at higher altitudes in the Central Valley.  At night it was markedly cooler and yes, it rained.

The following day I returned to the Osa Peninsula. The small plane had to fly directly through some very imposing rising cumulus clouds, which rather than being soft, white and fluffy, this time were dark and brooding.  The drop in air pressure within the clouds resulted in the plane being buffeting from side to side as well as rising and falling like an aerial rollercoaster.

Once back at Bosque, the rain really started to come down.  My first night back at the lodge removed any illusions that the wet season could be coming to an end.  It poured down continually from mid afternoon until well into the following day.  In fact it did not stop raining for 4 days, except for some very brief interludes of sun managing to break through.  My first week back had a total of almost 18 inches of rain.

Menacing Refugees

The incessant downpour had caused many to insects to seek refuge within the confines of my cabin.  A notable visitor was found under the eaves one morning resting on the beams, a Black Witch Moth, (Ascaphala odorata).  These moths belong to the Noctuidae family.  Although my specialty is with butterflies, I do have a liking for moths which unlike their day flying relatives tend to be more subtly rather than bright and garishly colored.  When you look at the markings of the Witch Moth you can see all manner of complex lines and banding with more luminous eye spots and crescents.

Witch Moth

Were I superstitious by nature, the presence of the Witch Moth in my cabin might prove cause for concern.  In Costa Rica, as in Mexico, the Witch Moth is known as the “Mariposa de Muerte”, the butterfly of death.  It is thought that if one of these creatures enters your house, someone in the house will die. As I live alone, that leaves only one option.  Thankfully I find them more beautiful than fearful.

As if a visit by the “Butterfly of Death” wasn’t bad enough, a large hairy mustachioed killer also made its way into my cabin.  I found a large black Robber Fly, (Family: Asilidae) on the screen of my window.

Robber Fly

The Robber Flies are true flies belonging to the order Diptera.  They are normally very robust insects that sit on vegetation awaiting a suitable prey item to pass by and with Robber flies the prey is basically anything else that flies.  With lightning quick speed, they capture the unfortunate victim in mid air.  The proboscis is modified into a lethal injection system which pierces the skin following which a cocktail of quick acting neurotoxin is delivered to kill the prey as well as strong proteolytic enzymes to digest its insides.  Once the internal tissues have been rendered into a soup within its own skin, the fly sucks out the resulting meal.  One of the Robber Flies diagnostic features is a moustache of stiff bristles around the mouth area called the mystax.  This protects the fly from possible physical damage by its dying victim.

Mallophora sp

When I first saw the fly in my cabin I had to look twice as at first I thought it was a bee, but closer scrutiny revealed its true identity but it didn’t take long to place it as one of the bee mimics, possible of the genus Mallophora.  The bee mimicking robber flies specialize upon killing and eating the bees they so closely resemble.

Welcoming  Committee

The first thing that greeted me upon my return to Bosque, was the high pitched dry twittering that I knew at once to be the familiar call of the Summer Tanager, (Piragna rubra), one of the late returning migrants coming home for the dry season, I can always be assured they will be around the grounds of Bosque when I myself return in mid November.

The Summer Tanager is only one of many migrants that swells the abundance and diversity of bird life at Bosque over the coming months.  They are joined by a plethora of warblers and birds from other assorted families.  The residents are here year round; parrots, macaws, toucans and trogons being the most visually obvious.

One of the birds that had been noticeable by its absence earlier this year was the Dusky-capped Flycatcher, (Myiarchus tuberculifer), which can normally be heard and seen around the area of the restaurant.  One my first day back I could hear its distinctive call once more and on the following day I did manage to see one not too far from my cabin.

There are several birds in the area that will be familiar to people by their call rather than being seen.  One of these, the Rufus Piha, (Lipaugus unirufus), has a very distinctive wolf whistle.  It is a common bird but not spotted very often.  As I emerged from my cabin the other morning, there was one individual sitting in the branches in front of me.  They normally sit for a while and then fly to capture an insect or spider before returning to the perch once again.

It will be some months yet before the butterflies start to show in any great numbers but we still do have several species prevalent, particularly in the Heliconiinae subfamily.  These are the tropical longwings and have a tendency towards bright garish colors.  Most Heliconiids are part of mimicry complexes which means there are more than one species that look the same and are often hard to identify separately from their co-mimics.

The gardens at Bosque are boasting the usual high number of flowering shrubs, namely a variety of heliconias and the ubiquitous Bambu Orchid.  The strange pendulous tendrils issuing from the trunk of the Cannonball Tree are hanging with both flowers and fruit.  Nearby another tree, Clusia rosea is in flower.  The cheesy scented Calabash Tree that produces its cauliferous flowers at a rate of one or two a night throughout the year is also blooming and fruiting.

Cannonball Tree Flower        Calabash Fruit        Clusia rosea flower

Two months ago, the pendulous tendrils of the Mucuna vines were in flower.  Now they have been pollinated and have the distinct hirsute bean shaped fruits that contain the seeds.  When ripe, the bean splits revealing the seeds, which are known locally as “Ojo de Buey” which refers to their resemblance to Ox-eyes.  They are quite often polished and used as ornaments in jewelry.  You must exhibit caution when handling the seed pod, as can be seen from the photograph they are covered in tiny urticating hairs which readily detach and become lodged in your skin, working their way into the epidermis and causing intense discomfort.

Mucuna Vine Flowers

Mucuna Vine Fruit

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

At this time of year when the ground is still very wet and covered by a lot of leaf litter, as you walk through the forest, every other footfall will probably reveal the presence of a small frog trying to jump out of the way.  What you are seeing, however briefly, are Rain Frogs.  Closer examination will reveal that these tiny amphibians sport a whole array of textures and colors to the skin.  Unfortunately when it comes to identifying the different individuals to species level, the problem is that the within one species there is massive variation.

Unidentified Rain Frog

So on a quiet Sunday morning I set out on the Zapatero Trail to try and capture some images of the rain frogs with a mind to producing a small identification sheet to help guests to know what they are seeing.  The Rain Frogs, being so small, disappear very quickly from view either under fallen leaves or blending in so well cryptically with the background.  Even if they remain exposed, by the time you have positioned the camera and composed the frame, quite often you will only be looking at where the frog was sitting moments ago but not now.

Unidentified Rain Frog

Unlike most amphibians which have to return to the water to reproduce, the rain frogs are totally terrestrial.  They pair up and lay 10 – 30 large, yolk filled eggs in amongst the leave litter.  The whole process of development takes place within the egg so there is no free swimming tadpole stage.  After 7 or 8 weeks a perfectly formed miniature copy of the adult emerges.

For the moment, the identification sheet will have to wait as I could not reach a conclusion as to which species I had identified.  The frogs were too small and diagnostic features such as shape of finger, amount of interdigital webbing where not observable.  Not to worry, I enjoyed the day out though.

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 80°F.  Average Daily Temp Low 72°F.

Average Daily Rainfall 2.49 ins.  Total Weekly Rainfall 17.42 ins

Average Daily Temp High 26.4°C.  Average Daily Temp Low 22.2°C.

Average Daily Rainfall 63.2 mm.  Total Weekly Rainfall 442.5 mm

Species List for the Week


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


  • Crimson-fronted Parakeet
  • Red-lored Amazon
  • Scarlet Macaw
  • Great Currasow
  • Roadside Hawk
  • Yellow-headed Caracara
  • Lineated Woodpecker
  • Pale-billed Woodpecker
  • Black-hooded Antshrike
  • Chestnut-backed Antbird
  • Northern Barred Woodcreeper
  • Plain Xenops
  • Wedge-billed Woodcreeper
  • Rufus Piha
  • Short-billed Pigeon
  • Common Paureque
  • Nicaraguan Grackle
  • Long-billed Hermit
  • Rufus-tailed Hummingbird
  • Stripe-throated Hermit
  • Red-capped Manakin
  • Chestnut-mandibled Toucan
  • Spectacled Owl
  • Cherrie’s Tanager
  • Gray-headed Tanager
  • White-shouldered Tanager
  • Bright-rumped Atilla
  • Dusky-capped Flycatcher
  • Great Kiskadee
  • Golden-crowned Spadebill
  • Streaked Flycatcher
  • Tropical Kingbird
  • House Wren
  • Riverside Wren
  • Black-throated Trogon
  • Black Vulture
  • Turkey Vulture


  • Central American Smooth Gecko
  • Cat-eyed Snake
  • Clawless Gecko
  • Common Basilisk
  • Four-lined Ameiva
  • Common Anolis
  • Golfo Dulce Anolis
  • Terciopelo


  • Marine Toad
  • Red-eyed Green Tree Frog
  • Banana Frog
  • Black and Green Poison Arrow Frog
  • Fitzinger’s Rain Frog
  • Long-fingered Frog
  • Masked Smilisca
  • Rough-skinned Rain Frog
  • Tink Frog


  • Anartia Fatima
  • Heliconius erato
  • Heliconius ismenius
  • Heliconius sapho
  • Hermeuptychia hermes
  • Morpho menelaus



  • Bamboo Orchid Flowering
  • Black Alligator Tree Fruiting
  • Calabash flowering and fruiting
  • Cannonball Tree Flowering and Fruiting
  • Clusia rosea Flowering
  • Golden Trumpet Vine Flowering
  • Monkey Comb Tree Flowering
  • Figs Fruiting
  • Mountain Rose Flowering
  • Ox Eye Vine Fruit
  • Stinky Toe Fruiting

2 responses to “A New Season Starts

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  1. Welcome back Philip. I am looking forward to another great year of updates from BdC via your blog postings.


  2. Great report – very educational.


    Ron Wilson, Canada

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