A Great Week For Wildlife on the Osa   11 comments

Philip Davison. Costa Rica. Blog. Nature Diaries


The last week has seen some very violent overnight rain storms in the area resulting in 21 inches of rain.  Many of the forest trees continue to fruit which provides a steady supply of food for the fruit-eating animals.  At the moment the nutmeg trees are raining down their distinct yellow fruits which give them the name “Fruta Dorada” or the “Golden Fruit” tree. Black-mandibled Toucans in particular are partial to this feast.  The mangoes have not yet been exhausted with the orchard providing readily accessible viewing of monkeys and coatis.  At night these are replaced y the Common Opossums and a large variety of moths which can be found feeding on the fallen rotting fruit.

An Outbreak of Moths

The migratory day-flying Green Urania moths are still present around the grounds in large numbers.  Their food plant, the Omphalea Vine will tolerate about 3 generations of the moth caterpillars feeding on its leaves before enough toxins have built up forcing the 4th generation adults to migrate to pastures new.

Urania fulgens

Green Urania, (Urania fulgens)

The Frangipani also hosts a regular outbreak of moth caterpillars – those of the Frangipani Hawk Moth.  Their distinctive black and yellow banded bodies stand out against the green leaves.  It does not take long before the caterpillars convert leaf tissue into caterpillar tissue and they can be seen growing larger and larger on a daily basis until one night overnight the huge grubs disappear to pupate and later emerge as the adult moths and the cycle will be repeated.  Unlike the Green Uranias that are obliged to travel some distance in search of non toxic host plants, the Frangipani Hawk Moth caterpillars sequester the alkaloid toxins of their larval food plant which they use as chemical defenses.  The Frangipani itself has the remarkable ability to grow new leaves almost at the same rapid rate at which the caterpillars consume them.

Plumeria rubra

Frangipani, (Plumeria rubra)

Pseudosphinx triota

Frangipani Hawkmoth Caterpillar, (Pseudosphinx triota)

Green Iguanas

This is the time of year when the Green Iguanas hatch from eggs that have been buried in the soil by the adult females.  When the juvenile iguanas first emerge they have bright lime green coloration.  The can be seen during the day sitting on rocks or vegetation sunning themselves.  At night they sleep on higher up in the vegetation, quite often towards the end of the leaves or on leaves that have long stalks.  Should a predator approach the sleeping lizard then movement of the leaf will alert the sleeping lizard which awakens, jumps down and runs away.  This individual was just basking by the pond but kept a wary eye on me as I lowered myself to the ground to get the photograph.  After the flash had fired once or twice it turned its back and slowly made its way to what it thought was a more comfortable distance.

Iguana iguana

Green Iguana juvenile, (Iguana iguana)

Iguana iguana

Juvenile Green Iguana Close Up

It is not often that the large Green Iguanas are seen around the grounds.  They spend a large part of their lives at the tops of the tree canopies.  Every so often one will make its way to the ground.  Unlike the juveniles the adults tend to be a darker mossy green in color.  Also, whereas the juveniles have a more insectivorous diet, the adults take a lot more vegetation.

Green Iguana

Green Iguana Adult, (Iguana iguana)

Flying Dragons

Larger animals are more noticeable but there are many smaller creatures, which once you look more closely at your surroundings also come into focus.  While taking its photo just behind the iguana at the pond dragonflies were alighting and then taking flight.  Their constant coming and going with a period of hovering over the water surface drew my attention away from the iguana which had now scuttled off.  I sat watching their behavior and noticing the water hyacinth leaves that certain individuals would favor.  I pointed the lens and focused in on the landing platform and waited.  It wasn’t long before landing pads owner would return from his brief search and settle.  Click and there’s the shot.  Sometimes with insect photography patience is a definite virtue.  Observe, plan and wait is a good maxim for getting the shot you want.

This particular species of dragonfly, Micrathyria ocellata is found throughout Central and
South America.  It inhabits ponds and ditches where the males are extremely territorial, constantly harassing and chasing other males continually throughout the day.

Micrathyria ocellata

Micrathyria ocellata

Grab The Moment

Whereas above I espoused the virtues of patience for insects sometimes an opportunity comes along and you have to take the shot in the moment.  Thankfully I normally use very few different settings on the camera when I know what my subject is going to be so there will not be a lot of changing aperture or f-stop or ISO.  If something lands in front of me and the subject will be there only fleetingly then I am ready.  There is no time for composition so I just have to take what I can get.  Sometimes it works and sometimes it doesn’t.

This paper wasp landed beside me while I was photographing butterflies.  The wasps are notoriously flighty and don’t tend to stay still for more than a few seconds.  This one was momentarily preoccupied with repositioning in its mandibles a grub it had caught.  That was all the time I needed and this time I captured the image.   Many previous occasions I have not.

The wasps are not always that easy to identify.  This one appears to be one of the drumming wasps, (Synoeca sp).  They are fiercely defensive of the nest and have a barbed sting that remains embedded in the body of any creature attempting to attack the nest.  For this reason they give ample warning of their intention to defend.  The nests are papery structures that can be found attached to tree trunks.  When under threat the wasps collectively hold the skin of the nest and violently vibrate their wings.  This produces the drumming sound that should not be ignored and if it is the consequences will be severely painful.

Synoeca sp

Drumming Wasp, (Synoeca sp)

Pretty Plain Skipper

And finally one of the butterflies.  For many people the appeal of butterflies are the bright poster colors, the fact they can be found visiting amongst the flowers in the garden flitting from bloom to bloom and don’t bite or sting.  There are many thousands of butterfly species in the Neotropics and many of them fit that description.  But there are probably as many small, insignificant and overlooked butterflies that lack bright cheerful colors.  The skippers are a large family of butterflies that are not easy to identify simply because they do not exhibit those obvious vivid patterns.

Urbanus simplicius

Plain Longtail Skipper, (Urbanus simplicius)

The spreadwing skippers come in many shapes and sizes.  The Plain Longtail, (Urbanus simplicius), is as its name describes.  It has little by way of markings and the hindwing is drawn out into two long tail-like extensions.  Paradoxically these features in themselves make it easier to identify.  Butterflies are my favorite creatures and I can see an innate beauty in all of them sometimes because that beauty is more subtle and not so garish.

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

11 responses to “A Great Week For Wildlife on the Osa

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  1. Thank you Philip! Love your interesting newsletters! Fain in Texas


  2. Hi Phil

    Very nice blog!!

    Pseudosphinx triota shold actually be Pseudosphinx tetrio 😉

    Cheers Dominik aka bayucca



  3. Great blog Philip and great photos!! Interesting read


  4. Amazing photos Philip


  5. Very interesting Philip, thanks for sharing. That’s a whole lot of rain in one week. Love the green iguano photos!


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