Being Yellow and Burning Nuts
Walking along the trails through the forest can sometimes be a visual feast in terms of animal sightings but at other times you may encounter very little at all. The air is very still and so there is quite often no sound of rustling leaves as when blown in a breeze. The temperatures are high, not as high as at the top of the canopy, but high enough to make someone more familiar with cooler climes to break into a sweat at the slightest exertion. The stifling silence maybe permeated by the white noise of calling insects.
At the moment there are many trees in bloom. The Nance trees, (Byrsonima crassifolia), are currently covered in bright yellow flowers which change to orange after they have been pollinated. The Nance flowers attract a lot of bees, particularly species of stingless bees native to the area. Several months from now the trees will bear huge numbers of the small yellow-skinned fruits that are consumed not only by a large number of animals but people too. The taste is unique and the fruits can be eaten raw or prepared as a dessert or as a refreshing drink.
Nance, (Byrsonima crassifolia)
One tree that has been flowering for the past month or so and is now producing fruit is the Cashew, (Anacardium occidentale). It has distinctive large red pear-like fruits beneath which the nut is suspended. The fruity looking object is the swollen meristem of the actual fruit which is the nut itself. It is known as the Cashew Apple or Maranon. This you can eat without concern. As with the Nance, the flavor is unique. It can linger for some time at the back of the mouth before fading away. The nuts are to be treated with a great deal more caution. Cashew belongs to the same family of plants as poison ivy, Anacardiaceae. The skin of the nut contains the volatile oil Cardol, which can cause severe blistering when in contact with the skin and more dangerously a burning of the eyes. Cashew nuts must be roasted or blanched to eliminate the oils. Even then the utmost caution has to be exercised as the oils can seriously damage the respiratory system, many people who work in the Cashew industry suffer very severe respiratory problems.
Cashew, (Anacardium occidentale)
While I was looking at the unripe green cashews I noticed another species of Leaf-legged Bug, (Family: Coreidae), that I had not seen before. A search through the literature would only provide me with the Genus: Acanthocephala. I have photographed several species in this genus but cannot get them any more specific than that. This one was feeding on the unripe cashew apple by sticking the dagger-like mouthparts into the flesh and sucking up the juice.
Leaf-legged Bug, (Acanthocephala sp)
Seen As Green With Orange Flags
From here and there bird calls drawn your attention to the distance. You become attuned to the slight rustles down by your feet. Further investigation reveals a lizard, one of the whiptails perhaps, scurrying off through dry leaf litter. Beside you there is a faint buzzing sound, a high-pitched hum. It is a hummingbird, its wings a blur, coming to scrutinize a piece of red clothing you are wearing. As far as the bird is concerned this could be a fresh bloom brimming with nectar but no such luck and off it goes.
As I was walking through the forest a quick flash of bright orange caught my eye near the ground. A male Golfo Dulce Anolis Lizard, (Anolis osae), was displaying to a female. He catches her attention and tries to gain her favor by flying a bright fiery orange flag, a dewlap, which is a loose piece of skin beneath his chin. It is supported by a thin rod of cartilage which is attached to the front of the jaw and over which he has muscular control. The more splendid the dewlap, the better his genetic make-up and the more desirable he will be to father her offspring. The female is a similar size but lacks the dewlap and has a series of dark diamonds down her back.
Golfo Dulce Anolis, (Anolis osae). Male.
Golfo Dulce Anolis, (Anolis osae). Female.
While I was lying on the ground photographing the lizards I saw a tiny metallic green fleck moving around. The movement was jerky as the fleck hopped from one dead twiglet to another. There was no mistaking that form of movement, it was a jumping spider. Many of the jumping spiders are minute. Unless you were looking for them or are familiar with their body movements then it is so easy to miss them. That would be a shame as they are fascinating little creatures.
Unidentified Jumping Spider, (Salticidae). Anterior Eyes.
Normally jumping spiders are inclined to turn and look at you. This one seemed to be distracted by something else and continually kept its gaze in the opposite direction to me so I could only really photograph its back. For a fleeting moment it turned to look at me and I managed to get a shot of the huge anterior eyes that the spider relies upon for seeing the prey item that it will actively hunt down.
Unidentified Jumping Spider, (Salticidae). Dorsal View.
Mammals, despite their sometimes large size, are notoriously difficult to find. Monkeys, when active, can make a large amount of noise as they crash through the trees. They can also be quite vocal. Coatis and agoutis on the forest floor can be detected b their movement. Coatis tend to huff and puff a lot as the females with juveniles constantly sniff out any consumable morsel lying in their path. Agoutis and squirrels can be heard gnawing their way through the shells of various fruit and nuts that form the bulk of their diet.
Cats on the other hand are largely silent. They are masters of stealth. Over the past week I have captured videos of an Ocelot walking the Titi Trail. One of the guests at the lodge crossed the path of a Puma on three different occasions over the last few days. On one instance the Puma was lying across the trail in front of her and had no desire to move. She slowly backed away while always facing the cat and finally headed off in a different direction. The cat could have cared less. The next day she came across the cat walking down the trail in front of her. A few days ago the Spider Monkeys were shrieking their cat-specific alarm call and sure enough one the guests staying in the Tropical Garden was lucky enough to see the Puma walking through the forest behind his cabin.
Deceptive Green Stripes and Giant False Bats
The forests, fields, hedgerows and gardens are normally filled with butterflies this time of year and that has been the case. One distinctive Lepidopteran that has been around in very large numbers over the past month is the Green Urania, (Urania fulgens). Its striking soot black wings striped with bright metallic green bands make it look so much like one of the swallowtail butterflies that people are surprised when they cannot find it in the butterfly guide books. It is, in fact, a migratory day-flying moth.
When walking down the forest trails at this time of year people are also fooled by yet another moth. This moth is so large that it is when it is spooked and takes to the air, its huge wingspan and flapping flight lead people that they are looking at a bat. This is the largest species of Lepidopteran on the planet, the White Witch Moth, (Thysania agrippina). If you have the good fortune to see it land you will notice that it orientates itself with the wings up and down. The light grey ground color of the wings now display in this vertically inclined position darker wavy, zig-zag markings, which if the moth has landed on a pale barked tree, render it almost impossible to see as they resemble crevices in the bark. Despite they are reasonably common moths throughout Central and South America, very little is known of their life history.
White Witch Moth, (Thysania agrippina)
Philip Davison Is a Biologist, Writer and Photographer Based in Costa Rica
The days are now consistently sunny, hot and dry. Changes are happening in the observable flora and fauna. Butterfly numbers are increasing in terms of both the number of species and the number of individuals. But the numbers are still very much lower than would be expected for this time of year. It could well be that the extended and intense rains of November resulted in the death of many larvae and pupae. It may take time for those numbers to recover, especially considering the continuing decline seen over the recent two decades.
This time of year is usually noteworthy for the trees and other rain forest plants coming into flower. There is some visual evidence of several trees coming into bloom but once again not in the number or variety associated with the onset of the dry season.
One other creature notable by its absence at the moment are the cicadas. January is regarded as the start of a three month period when, during the day at least, your eyes are subject to a continual sonic bombardment of an indescribable intensity. The larval stage of the cicada is spent below the ground where they feed on sap from plant roots. It is not beyond the bounds of possibility that many of the larvae were drowned thereby reducing the number of emerging adults which are generally to found in millions this time of year. For many people that aural attack will not be missed but the ramifications on the ecosystem may have long lasting effects.
One feature of the transition from the wet into the dry season that is very evident as you walk through the forest at this time of year is the production of new leaf. The feature that makes the new leaf so obvious is the color – red. Cabo Matapalo is on the South West tip of the Osa Peninsula, Costa Rica. The location is only 8⁰ North of the Equator. Any sunlight hitting the earth’s surface at this latitude is therefore intense sunlight and significantly high in ultra violet radiation. Ultra violet radiation damages developing tissue. The plants produce a red pigment called anthocyanin which is deposited over the developing chloroplasts and protects them from irradiation.
Red is the Color of New Leaf in the Rain Forest
As the chloroplasts mature the plant reabsorbs the anthocyanin and now lays it down as a layer on the bottom of the leaf surface. Light hitting the forest floor is only 1% of that hitting the canopy so light is of a premium. Light hitting the leaf will pass through and be bounced off the underlying red layer and reflected back up through the leaf surface so that any light required by the plant to carry out photosynthesis it missed on the way down it will pick up on the way back through.
Many of the young leaves hang droopily facing down. Those that have no anthocyanin and not having developed much chlorophyll, look pale and ghostly in the in the gloom beneath the canopy. At this point they are flaccid and not until water is absorbed by the cells do they become turgid and assume their horizontal light gathering aspect.
One of the butterflies that exhibits very profound seasonal fluctuations is the White Banded Fatima, (Anartia fatima). It is one of the commonest Costa Rica butterflies. It is hard to miss with the white bands on the wings contrasting starkly with the dark brown ground color as it flies in open sunny areas such as gardens and disturbed ground. It can be seen visiting a wide variety of nectar plants.
White-banded Fatima, (Anartia fatima)
White-banded Fatimas can be found throughout the year in greater or lesser numbers. This week the numbers started to increase very rapidly. In some locations there were dozens of them, all looking fresh and new. But once they reach a peak in numbers and the short-lived reproductive frenzy is over then it will not take long for them to start to take on a tattier appearance and finally within a couple of weeks they will have more or less all gone again. But later in the year the cycle will repeat.
As the dry season progresses then the creatures that live on the forest floor take shelter in the moister damp conditions beneath the leaves that litter the ground during the heat of the day. As you walk on the trails and your feet disturb those leaves that disturbance will flush the smaller creatures from their hiding places. You will see displaced skinks, beetles and frogs seeking safe refuge from your footfall and the sunlight.
Rough-skinned Dirt Frog, (Craugastor rugosus)
There are several small frogs that inhabit the forest floor. These are the rain frogs mostly in the genus: Craugastoridae. On the forest trails there are two species in particular that you may come across, the Rough-skinned Dirt Frog, (Craugastor rugosus), and Stejneger’s Dirt Frog, (Craugastor stejnegerianus). The Rough-skinned Dirt Frog, as the name suggests, has a skin covered in many protuberances. Stejneger’s Dirt Frog on the other hand has a smoother skin and a generally darker area behind the eye.
Stejneger’s Dirt Frog, (Craugastor stejnegerianus)
Both these species have life histories that have allowed them to decrease their dependency on water and become more terrestrial in habit, certainly in respect to reproduction. Whereas most amphibians must return to the water to breed, the rain frogs pair up and lay their eggs amongst the leaf litter on the forest floor. The microclimate beneath the leaves is damper than that above which suits both the frogs and their eggs, it stops them from drying up. Aquatic egg-laying frogs face the problem of having many predators in the water that will feed on the eggs and the tadpoles. Rain frogs do not face the same intense predation pressure and can therefore produce fewer but larger eggs. The larger size of the egg allows full development of the tadpole within a protective gelatinous coating. A larger amount of yolk is provided which supplies enough sustenance for the frog to complete development and emerge four or five weeks later as a tiny copy of the adult.
Stejneger’s Dirt Frog – One too many flashes and It’s Away.
Jumping in Color
Moments after photographing Stejnegers’ Dirt Frog I noticed a tiny black speck of a leaf which moved in a very distinctive and familiar fashion. The almost indiscernible black dot was a jumping spider. It had turned to look at me which is how it gave away its presence. I had to turn the camera lens on it and take same photographs to truly appreciate the amazing little creature I had in front of me.
Jumping spiders belong to the most diverse spider family: Salticidae of which there are more than 5,000 named species around the world. In Costa Rica there is not a wealth of reference material you can consult in an effort to make an identification. Sometimes family level is about as far as you can go.
Unidentified Jumping Spider, (Salticidae).
The most distinctive feature of the jumping spiders is the large anterior forward facing eyes. These give the spider the ability to see things at close range. They can be seen orientating themselves to watch you. That is what this one was doing with me. Unlike their web-building relatives, the jumping spiders hunt their prey down. Once they identify a potential meal they will pursue it and at the last moment pounce on it, deliver the venomous bite and consume it.
Their visual abilities allow them to use coloration as a cue in mating. The males may have brightly colored legs and pedipalps to court the females. This species had bright blue legs and yellow pedipalps. When a male sees a female he performs a series a ritual dance moves which include lifting his legs in a certain sequence as well as moving in a series of set maneuvers in front of her. All the while the female is watching, scrutinizing the performance. One blunder and she will leave having no further interest. Each species of jumping spider has a very specific dance routine thereby negating the change of courting the wrong type of girl.
Unidentified Jumping Spider. Look at Those Eyes.
One of the most distinctive flowers of the forest understory is that of the Aristolochia vines otherwise known as the Dutchman’s Pipe Vine. As with most flowers the sole purpose is the achieve reproduction through pollination. Many plants have evolved ingenious means by which to use the flowers as a means to this end. The Dutchman’s Pipe is one of them.
The flowers are named after their resemble to the carved tobacco smoking pipes used in Holland. But to a carrion fly they look somewhat different. Carrion flies are attracted to the fetid odor of rotting flesh. The flowers of this species of Dutchman’s Pipe, (Aristolochia gaudotii). give off a scent which mimics the stench of a putrefying body. The pale yellow base color reticulated with maroon blotches visually emphasize the illusion.
Dutchman’s Pipe, (Aristolochia gaudotii)
The flies land but find themselves incapable of maintaining a footing on the slippery oily inner surface of the flower and slip down into the interior. They are unable to make an immediate escape as their exit is blocked by a barrage of downward pointing stiff hairs. They are trapped. During the period of vegetative incarceration, the fly struggles violently in order to gain its freedom. This results in the body becoming covered in pollen. The following day the stiff hairs wither and the fly finds its exit clear only to fly off and respond to the same trickery. This time it transfers the pollen thereby pollinating the flower after which it will be released from its temporary floral prison with a fresh coating of pollen.
Dutchman’s Pipe. Looking Down Through the Prison Bars.
Philip Davison is a Biologist, Writer and Photographer Based in Costa Rica
Observation Lists for Week Ending Monday 16th January.
Mexican Mouse Opossum
Greater White-lined Bat
Central American Spider Monkey
Golden-mantled Howler Monkey
Alfaro’s Pygmy Squirrel
Golfo Dulce Anole
Asian House Gecko
Central America Smooth Gecko
Central American Whiptail
Fitzinger’s Rain Frog
Rough-skinned Dirt Frog
Stejneger’s Rain Frog
Red-eyed Green Tree Frog
Savage’s Thin-fingered Frog