The heavy rains have continued through into this week. The heavens generally open later in the evening which is an ideal situation as the next morning the sun rises with a blue sky which leaves the day free to explore and take photographs. Well that happens on some days but progressively it has been raining late afternoon and sometimes continuing over night into breakfast time. The creek is running with water again, at least in the upper and lower stretches but it will take a little longer for the full flow to resume.
An Explosion of Nymphs
One noticeable feature of this week has been an explosion in butterfly numbers both in terms of species and individuals. More particular this has been the case with three particular species of butterfly in the Nymphalid family; the White-banded Peacock, (Anartia fatima), the White Peacock, (Anartia jatrophae), and the Tropical Buckeye, (Junonia evarete). Not one of these three species is rare or uncommon and they can be found in greater or lesser numbers throughout the year depending upon season. They do have cyclic emergences which suggest two broods may occur over the course of a year but over the last week significantly all three have suddenly emerged in huge numbers.
White-banded Peacock, (Anartia fatima)
White Peacock, (Anartia jatrophae)
It may well be that the rains arriving in April along with high temperatures have meant that the larval food plant of these three species has been able to produce a lot of vegetative growth which in turn has provided a sufficiently adequate amount of food to support a greater number of caterpillars. The White-banded Peacock and the White Peacock caterpillars both feed on similar plants, namely those in the family Acanthaceae. The Tropical Buckeye feeds on plants in the family Verbenaceae but in Costa Rica it is not known of which species. Significantly all three species are found in open habitat such as grasslands rather than within the forest. For that reason their presence is more obvious in the gardens around the lodge.
Tropical Buckeye, (Junonia evarete)
A New Cracker
As well as all of the peacock and buckeye butterflies flying around there are also large numbers of the Green Urania moths still residing in the locality. But they are not the only lepidoptera to be observed. This wet season seems to have been favorable to many other species, some of which live in the forest and others at the top of the canopy. I have lived in the area for sixteen years and part of my research is the monitoring of butterfly populations. In that time I have recorded 380 species at ground level in the area. Some of those species occur regularly but there are others that I have only seen once and then never again.
There are several species of cracker in this locality. They most certainly are not a commonly observed butterfly. Last week I was returning to the lodge after photographing some other butterflies when I noticed on the side of a tree a species of cracker that I had not previously recorded from this area, the Red Cracker, (Hamadryas amphinome). It is always sod’s law that if I see a new butterfly species that I am generally not carrying the camera. This time I was. The lighting was good and the subject was in the perfect position so I got a good shot.
Red Cracker, (Hamadryas amphinome)
The male crackers typically perch on the side of tree trunks with the head facing down. The name refers to their habit of emitting an audible cracking sound. Research has shown that the cracking sound is made following the upsweep of the wings which make contact at high speed at the top of the stroke. One of the wing veins is expanded which acts as a resonating chamber to amplify the sound of the crack. It is assumed that the cracking is made by the males as part of the territorial or mating behavior but results are not as yet conclusive.
One butterfly commonly seen flying around the garden areas is the Cloudedless Sulfur, (Phoebis sennae). It bright lemon yellow coloration is immediately catches your attention as it flutters its way across the lawns. But despite the fact that it is reasonably common it is extremely difficult to photograph. The adult rarely seems to land and when it does it is only for fleeting moment before it is off again. You have to be fortunate enough to be in the right place at the right time.
Cloudless Sulfur, (Phoebis sennae)
At night however they sleep, for the most part under wide leaves close to the ground. As long as you work without too much disturbance this then provides an ideal opportunity to capture its image as it is not moving at all. Too much light will cause it to wake and it may fly off in a very bewildered fashion.
There are two species of butterfly to be commonly found in this area which are almost impossible to tell apart. They are both commonly known as Giant Swallowtails. The two species in question are Heraclides thoas and Heraclides cresphontes. The males can be distinguished under close scrutiny but the females provide more of a challenge. In fact the best way to distinguish the females is to watch and see which plants they visit to lay their eggs; H. thoas only uses plants in the pepper family; Piperaceae whereas H. cresphontes uses a whole variety of genera in the family; Rutaceae.
Giant Swallowtail, (Heraclides thoas)
The caterpillars are quite distinct and the fact that they feed on different food plants makes identification easier. They both resemble bird droppings being shiny and brown with creamy patches. H. thoas has one creamy patch while H. cresphontes has two. I found this group of H. cresphontes caterpillars quite low to the ground on a small shrub which within a day or two they had consumed and the caterpillars themselves had disappeared. A bird dropping is not going to appeal as a food source to many animals so the caterpillars can feed in the open without too much concern of being preyed upon by larger predators such as birds and lizards. The deception might not prove successful against parasites and parasitoids though.
Giant Swallowtail, (Heraclides cresphontes), caterpillars
A close look at some of the plants as you walk around the trails will reveal various oddly shaped structures which suggest something has gone wrong with the leaf development. To a certain degree this is true. These weird, and to some people, ugly growths are leaf galls.
Leaf galls are the plants reaction to the invasion of another organism and there are many organisms that can induce gall development including bacteria, fungi, nematodes insects and arachnids. The appearance of the gall is host specific so for those who study galls, cecidologists, the organism causing the gall can be identified very quickly. Sometimes an infestation may occur but for the most part the gall producers do not harm the host.
Unidentified Plant Galls
With insect induced “closed” galls, the adult lays an egg within the leaf tissue. The egg hatches and when the larva emerges contact between the larva and the meristematic vegetative tissue causes excess cell multiplication thereby forming the gall. The larva develops within the gall protected by its walls and feeding from the underlying starch and sugar rich tissue.
Because the gall causing agents are so numerous it requires the eye and the knowledge of an expert to be able to effect an identification. My guess is that these galls were caused by an insect possibly in the Order: Diptera. I would welcome any input from a gall expert who may be browsing these pages to help reveal the causal organism of these galls.
Bird nests are one of those things that can generally only be found serendipitously. Hummingbird nests despite their small size are the most commonly seen of the nests as they tend to be built in more open locations either secured to a small branch or fastened with spider web beneath the tip of a Heliconia or palm leaf.
However on occasion something will catch your eye that isn’t all that it seems. Only about eight feet off the ground just to the side of the trail I found what looked like a tangle of fallen vegetation. But there was something about the way it was lying in the fork of a small tree that did not appear random. A look with the binoculars I could see that top of a birds head poking out above a moss-lined cup on top of the tangle. There was not much to see but I was reasonably sure it was a female Golden-crowned Spadebill. I returned several times to hopefully get a picture of her sitting on the nest but with no luck. I didn’t want to cause any disturbance so I just photographed the nest without its owner.
Golden-crowned Spadebill, (Platyrinchus coronatus), nest
One evening in the restaurant following the nightly deluge a small distinctively patterned snake was found lying on the wall, a Dwarf Boa, (Ungaliophis panamensis). It is not a snake that is frequently seen as it inhabits the canopy where it can be found occupying the inner recesses of larger bromeliads. I have found them around the lodge several times over the years. This one may have been knocked out of the tree tops by the torrential downpour that had just occurred.
Panamanian Dwarf Boa, (Ungaliophis panamensis)
They are called Dwarf Boas because they never grow to a size larger than 2 feet in length. Due to the small size the adults probably prey upon frogs and lizards found amongst the epiphytic growth at the top of the trees.
Philip Davison is a Biologist, Writer and Photographer based in Costa Rica.
FLIGHT NOT AFFECTED BY RAIN
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.
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.
Frangipani, (Plumeria rubra)
Frangipani Hawkmoth Caterpillar, (Pseudosphinx triota)
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.
Green Iguana juvenile, (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 Adult, (Iguana iguana)
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.
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.
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.
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.
The Wet Season
Last year on the Osa Peninsula the wet season started much later than normal. It did not start raining heavily until July. However, despite the delayed start, by the end of the year there had been more rain than the annual average. This year the rains arrived at the time when they are normally expected which tends to be mid April. The month of May and so far into June experienced a lot of rain. The forest and the gardens are currently looking luxuriantly verdant. There is a reason why the wet season is commonly referred to as the green season.
Sometimes if the initial rains of the green season are particularly heavy and the downpours are long in duration the force of the falling rain can knock blossoms from the trees that flower this time of year adversely affecting the fruiting season and consequently the amount of food available to the fruit-eating animals. The year 2005, which will be remembered by many as the year that Hurricane Katrina hit the southern area of the United States, in Costa Rica translated into a very wet green season. Many of the trees did not produce fruit and so fruit-eating mammals and birds such as Spider Monkeys and Black-mandibled Toucans were dying en masse due to a lack of food.
Conversely if the weather is unseasonably hot and dry, eventually amounting to what is a drought situation, then the plants put a lot of energy into reproduction resulting in a glut of fruit. These dry periods may be of short duration, eventually the rains will arrive, but in the meantime the animals benefit from a surfeit of food. This in turn may result in enhanced breeding success.
The small mango orchard at Bosque del Cabo has a two year cycle. One year the trees produce fruit the next year they don’t. Sometimes they will produce a bumper harvest and that is what has happened this year. The boughs of the trees are hanging heavy with fruit. The ground beneath the tree crowns is covered with fallen fruit.
Fallen Mangoes Cover Ground
Mangoes, (Mangifera indica), are not native to the Americas, they are originally from South-east Asia, more particularly from India, through Myanmar and into Southern China. As they produce such a bountiful crop of fruit they now can be found growing in all parts of the tropical world that have climatic conditions suitable for their cultivation. They are related to both Poison Ivy and Cashew. Just as with those two plants some care has to be exercised by individuals who demonstrate a reaction to physical contact with them.
Part Eaten Mangoes
Coati and Monkey Feeding Frenzy
During the day the activity in and around the mango orchard is prolific and intense. The trees are full of Spider Monkeys crashing around from branch to branch, noisily engaged in minor intra troop disputes. The monkeys are wasteful feeders. They pluck a fruit, take a bite and then throw the remainder to the ground. You have to be very careful standing under the trees when observing their behavior as even a soft fleshy fruit like a mango when dropped from a height can cause concussion if it lands directly on your head.
The discarded fruit on the ground starts to putrefy and ferment giving a pungent fruity smell to the area. The rotting fruit becomes irresistible to many animals both vertebrate and invertebrate. Some years ago the White-nosed Coati population suffered a severe crash in numbers; it was very difficult to see them. An occasional solitary male may have been seen but the large groups of females with young were very noticeable by their absence. However in recent years the population has rebounded and there are lots of White-nosed Coatis everywhere. The males tend to very bold and will only move away when approached very close and even then sometimes reluctantly. The females with young form large groups, sometimes numbering 15 – 20 strong. They are much more wary of an advancing human and will disappear into the undergrowth very quickly. The juveniles bound away emitting high pitched squeals while the females which hold their ground a little longer huff, puff and growl to voice their discontent. That was until the mangoes became freely available.
White-nosed Coati Feasting on Mango
The plentiful supply of easily obtainable food falling freely from above guarantees that daily a huge group of coatis will be congregated in the mango orchard gorging themselves on the ripe fruit. They are not inclined to move away from this bounteous treasure trove of a feast upon which their gluttony can be satiated. These normally shy and retiring crèches of women and children that disappear so quickly when otherwise approached will now hang on until you are within a foot or so. Even then they back away reluctantly, keeping an eye on you whilst trying to drag their juicy treat with them. Due to the number of people walking back and forth through the mango orchard the coatis have probably come to realize that you pose no imminent threat.
Spider Monkey Gatecrashes Party
As I was sitting on the ground taking photographs of the coatis a Spider Monkey descended down to the base of one of the mango tree trunks and sat watching all this activity. After a few minutes it decided to join in and despite the profusion of fruit above in the branches for whatever reason it wanted to partake of the ground based cornucopia. Picking up one mango after another, holding it close to the nose to smell, it then selected one which it deemed to be a choice morsel and ascended the trunk once again to consume it.
The coatis and the monkeys are very visible but as you walk through the orchard then there are other smaller forms of life that will briefly take to air from around your feet. They circle around but the food that had attracted them in the first place is too good to give up and so back they return to continue feeding at the same spot before being disturbed by your footfall. This is very convenient as you can now slowly position yourself in the knowledge that within a few minutes or less you will be able to get some good shots of the insects.
Common Ur Satyr
Many butterflies in the adult stage are attracted to and feed from the juices of rotting fruit. If you can cope with lying on a soft and squishy carpet of putrid mangoes then you can normally fill the frame with your subject. The Common Ur-Satyr, (Taygetis thamyra), is, as the name suggests, not a rare butterfly but because of its retiring nature and habit of living in dark secluded areas is not often observed. The mangoes proved to be too much of temptation. I noticed it from a distance but as I edged closer it took to the air. I stood very still and back it came alighting on the same spot from which it took off. I lowered myself very slowly, first to my knees, then leaning forward on my elbows and finally on my belly with the camera held in front of my face to focus on the subject. Worming my forward until I finally had the butterfly filling the frame, I clicked the shutter and thankfully the flash did not spook the butterfly and I had the shot.
Just in front of the butterfly and closer to me was another rotting mango but with a fly feeding from it. I have a liking for all creatures even things like humble house-flies which take on a different aspect when viewed close up. All I had to do was re-adjust my position by 90º and the shot was mine. I squirmed around to the side without disturbing the fly which was preoccupied with imbibing fruit juice and once again I had a series of successful photos.
House Fly Species
Flies, like butterflies, belong to the Class: Insecta but unlike butterflies, (Order: Lepidoptera), which have two pairs of wings, flies, (Order: Diptera) only have one pair of wings. Butterflies have a proboscis which functions not unlike a straw. The butterflies can suck up and feed upon a liquid diet that normally consists of nectar but also in this case mango juice. Flies have a similar feeding strategy but the mouth parts can have undergone a lot of modifications to allow them access to a greater variety of liquid sustenance including nectar, fruit juice but also blood, animal secretions, plant sap and decomposing vegetation and feces. Some, as can be seen in this photo, have a flat sponge-like end to the mouthparts which allow them to soak up imbibe the liquid mango meal.
At night the orchard is populated by a new set of animals, lured by the heady sweet aroma. Searching the ground with a flashlight will reveal a great many moths, their eyes lighting up like fire-orange spots burning through the darkness. You will see many species but unfortunately moths are not the easiest of insects to identify to species level; there are so many species and for the majority we know little of their life histories. Because they are for the most part nocturnal moths do not receive the attention their day flying butterfly cousins are subject to. However if you take the time to take a close look then what may have seemed like a dull brown winged insect turns into one of nature’s exquisitely patterned works of art.
Black Witch Moth
The Black Witch Moth, (Ascalapha odorata), is a fairly common moth in this area. It is known by native peoples in various parts of the Latin world as the “Moth of Death”. The story is that should one of these moths enter dwelling housing a sick person then that person will die. For me it is the richly colored intricately woven patterns crossed by a silvery blue band that kills me with delight in its presence.
Philip Davison is a biologist, photographer and writer based in Costa Rica.
Monday 22nd February
Into the Oven
The temperatures have continued to remain around 40ºC (104ºF) mark for several months now. Coupled with this has been the sharp decline in rainfall from mid December as the dry season progresses. January experienced little more than one and a half inches of rainfall. It is now that the forest floor begins to take on a dry and dusty appearance and despite being only two months into the dry season small cracks have begun to appear underfoot. Not many people complain of the blue cloudless skies though which give day long bright and sunny conditions.
Two animals have been seen in the area over the last week that are not frequently seen. The Brown-throated Three-toed Sloth, (Bradypus variegatus), is a reasonably common rain forest mammal. It would not be unusual to see one in the area given their relatively high density of numbers. The problem is that they live at the tops of the trees, don’t move too far or too fast and have a fur that is tinged green with algal growth ensuring that it does not stand out but rather blends in. That is a situation that lends itself very nicely to an animal that cannot move too fast in an effort to escape predation.
There is a second species of sloth that inhabits the area though; Hoffman’s Two-toed Sloth, (Choloepus hoffmani). They don’t occur in the same high numbers as the Three-toed Sloth and also prefer to forage at night which makes them less likely to be seen by the casual observer. But one was located one afternoon high in the canopy by Matthias Klum, a world renowned Swedish wildlife documentary maker who works for National Geographic while walking the Zapatero Trail while on a recent trip to Bosque del Cabo.
Up in the canopy the Two-toed Sloth can easily be distinguished from its Three-toed cousin by the color of the fur. The former is very pale blond while the latter is a mid grey. Closer examination with the aid of binoculars will reveal the Hoffman’s has a longer face and lacks the markings which appear to give the Three-toed a permanent benign smile.
Both species consume leaf although the Two-toed has a much wider range of tree species from which it will feed. Also the Two-toed will supplement its diet with insects, chicks and eggs.
Hogging the Limelight
The area around Cabo Matapalo is home to several herds of Collared Peccary, (Tayassu tajacu). Although only distantly related to pigs they do look for all intents and purposes like small wild boar. Many of the visitors from the Southern United States are more familiar with them as Javelinas.
Just as with the sloths there is a second species of peccary that can be seen but only very occasionally. The White-lipped Peccary, (Tayassu pecari), is much larger than its collared cousin and prefers more pristine conditions. They tend to stay within the confines of Corcovado National Park but once in a while a migration will occur and a group will make their way along the Pacific coastline. Last week there was a small herd of about 16 individuals that passed by and stayed at Bosque del Cabo for the duration of a few days.
Both species of peccary are essentially herbivores and will take fallen fruits, dig up tubers and browse on leaves. The Collared Peccaries exist in smaller herds, which in this area number around 25, while the White-lipped Peccaries can be found in herds of 300. The Collared Peccary as the name suggests has a white ring around the body in the area of the shoulders. The White-lipped Peccary as the name equally suggests has the fur around the mouth area colored white. The White-lipped Peccary is also much larger and with long shaggy hair.
The presence of the White-lipped Peccary is hard to mistake. As they move through the undergrowth they continually huff and puff while at the same time clack their teeth. They also have a very powerful odor that is not pleasant to the nose of human observers. The herd passing through Bosque arrived overnight and then several days later disappeared as quickly as they had come.
Taking over the Airwaves
From January through to March the daily soaring temperatures and bright sunlight stimulate a constant high pitched white noise. This is cicada season. The cicadas in this area have a two year life cycle but that is staggered so that there is an annual emergence of cicada adults at this time of year.
Cicadas live most of their life in the nymphal stage below the ground where they feed by tapping into the vascular system of the roots and imbibing the sap. They progressively grow through a series of moults until after two years they are ready to emerge. The final nymphal stage emerges from the ground one night and climbs the nearest available tree or sapling. Within several hours the exoskeleton splits down the back and the new adult pulls itself out of the old skin. This is the winged, reproductive dispersal stage in the insects’ life history.
The newly emerged and fully winged adults fly to the top of the trees. The next morning as the sun rises and the temperatures climb then the calling begins. The males have two sound producing organs on the underside of the abdomen called tympani. Each one is like a tightly drawn drum skin. The increasing temperature throughout the morning enable the cicadas to vibrate the muscles connected to the tympani more rapidly which in turn vibrate the drum skins more rapidly resulting in a the volume and pitch of the sound they create to increase. Conversely should the clouds traverse the sky and obscure the sun then the temperatures drop and the pitch lowers and the sound softens. If the clouds persist then the calling may cease completely. Once they clear and the sun shines afresh the sound will rapidly rise to a crescendo one more time.
The female is attracted to the sound of the calling male and lands beside him. She does not call except by way of an almost inaudible clicking sound. They pair up and mate. The female lays her eggs in the bark of a tree. When the eggs hatch and the larvae emerge they fall to the ground where they quickly burrow beneath the surface to tap into the tree roots and feed on the plant sap. There they will spend the next two years before emerging and starting a new generation of cicadas.
From the Same Old Record to A New Record
After sixteen years of monitoring butterfly populations at Bosque del Cabo it is always a thrill when a new species not recorded for the lodge turns up. Recently I had the good fortune to have a new species to add to the list. It was encountered during the course of my weekly butterfly count.
It was spotted flying close the forest edge quite low down. I saw it alight under a leaf about 8 feet off the ground. Unfortunately the angle at which the leaf was suspended and the proximity of the other leaves meant that the butterfly was not presented in the best way to photograph. I did manage to get enough information to make an identification though. It turned out to be one of the metalmarks, Family: Riodinidae, this individual being of the species Thisbe lycorias. It is by no means a rare butterfly and in fact is widespread throughout the country. But nonetheless it was not a species I had seen before.
Philip Davison is a biologist, writer and photographer based in Costa Rica
Tuesday 2nd February 2016
Senna to Sleep
Over the past few weeks many of the trees have started to flower. The increasingly dry conditions stimulate blooming at this time of the year but because most of the floors are 100 foot up in the forest canopy then the only time the visitor has to see them is when flying over the forest or when the spent blooms fall to the ground and lie littering the forest floor amongst the dry leaves. However there are some smaller trees, shrubs and herbaceous plants that grow beneath the canopy or in more open conditions. Here you can get to see the floral display at a closer proximity.
One of those small trees generally found growing along sunny paths and roads is the Saragundi, (Senna reticulata). Its bright yellow flowers tinged with a hint of orange stand upright like fat golden candles giving the whole of the tree crown an overall fiery glow against the green background of the forest or azure blue of the sky. Stand beneath the tree and you will hear the constant buzz of bees attracted by its flowery display as they come to take nectar and pollen.
Despite its showy appearance Saragundi is not a welcome part of the native flora as far as farmers are concerned. It is a rapidly growing weedy tree that will quickly invade and take over open areas such as pasture land and nor is it easy to eradicate. It is little wonder that the local gardening team around here hates them with a vengeance and cut them down as soon as they germinate.
Should you see a Saragundi later in the day, more towards dusk, you will notice that the leaves start to droop and the plant goes to “sleep.” This is a feature common to many plants in the Fabacaea family, (legumes), and it is known as a nastic response. The base of each leaflet has a fleshy elbow called a pulvinus. During the course of the day the rhythmic flow of potassium ions causes water to either enter or exit the cells of the pulvinus. In the morning the large water holding cells become full of water making the pulvinus turgid which holds the leaflet out straight. At dusk water exits the cells making the pulvinus flacid and so the leaflet folds down appearing as if to go to sleep. It is not known what evolutionary benefit this nyctinasty conveys on the plant but it most certainly looks like some of the forest trees are dozing off for the evening.
A Rod of Gold
Growing along the currently dusty roadsides or lining the forest edge abutting the gardens are weedy long-stemmed plants that have a crown of yellow flowers atop. These are the Jackass Bitters, (Nuerolaena lobata). It belongs to the Aster family which includes the daisies and dandelions. It is one of the most species rich families of plants on the planet rivaled only by that of the orchids.
The flowers heads are composites; each individual head is a group of flowers, the greater display of many flowers together provide a more attractive visual target to potential pollinators.
There is a lot of folk medicine currently based on the supposed curative properties of Jackass Bitters but none that has any scientific backing. However its anti diabetic qualities are being scrutinized in a laboratory situation with regards to its ability to exert some control over blood sugar levels.
Canna Look at Your Lily
Tucked under the shady conditions beneath the taller vegetation where the garden meets the forest edge are a low growing plant with yellow flowers. These are the Canna Lilies, (Canna x generalis). It is mostly a hybridized form cultivated to bring a splash of color to leafy green flower borders. It is not obvious from which natural species of Canna that this variety has been hybridized but it is possible that it may be a Neotropical native Indian Shot, (Canna indica). You will seeing this variety growing freely in many garden situations around the country.
Going Bats for Garlic
Going for a walk through the forest this time of year may certainly cause a stimulation of your olfactory senses. There are many scents and odors that seem vaguely familiar but you cannot quite put bring to mind what it is simply because it out of context. Currently walking through the forest there are areas where you experience the definite smell of chives, or is it onions, no wait a minute it is garlic. What would garlic be doing growing in a tropical rain forest situation?
Here and there along the forest trail there are patches of yellow flowers littering the forest floor en masse. At this point the aroma of garlic is very strong. The flowers lie for some distance concentrically around the base of a large tree which given its appearance looks more like a tree from higher temperate forests. The bark is rough and deeply fissured, closely resembling an Oak Tree than a smooth bark tropical tree. This is the Ajo or Garlic Tree, (Caryocar costaricense), so named because its flowers give off a scent reminiscent of garlic.
There is very little wind in the Pacific lowland forests of Costa Rica so the plants have to rely on animal agents for pollination and seed dispersal. Bats are very important pollinators and seed dispersers but bats prefer musky smells rather that sweet smells which is why there are some very strange odors in the forest. It is the scent of garlic that attracts the bats in so the Garlic Tree is a bat pollinated tree.
Seeing Things in a Different Light
On the hot sunny days of the dry season many butterflies can be seen flying around the garden areas. There are several species that are noticeable due to their striking yellow coloration. These could be the “butter” flies. These are the sulphurs and they are not easy to tell apart species wise unless you have them in the hand.
Sulphur butterflies belong in the Subfamily: Coliadinae of the family: Pieridae. To the human eye the butterflies all have yellow coloration to a greater or lesser extent. Some may appear to be more creamy-yellow, others lemon yellow and yet others orangey-yellow but without exception – yellow, hence the name sulphur. But that is not how they look to other butterflies.
Butterflies, unlike humans see light at the ultraviolet wavelength of the electromagnetic spectrum. The dorsal surface of the male sulphurs wings are colored with a yellow pigment. This re-enforces a reflective ultra violet component that covers most of the dorsal wing surface and appears to sexually attractive to females which only have a small amount of ultra violet reflectance on their wings in comparison. The ultra violet patterning is used by the males in courtship displays. To human eyes the butterfly appears as a dancing honey colored piece of confetti. The females however see something different. Larger males with bright reflective radiance appear to be more attractive to larger females. In the world of the sulphurs flashy show offs get the girls.
Philip Davison is a biologist, writer and photographer based in Costa Rica.
Weather January 2016
Max Temp 40.0ºC (106ºF) Max Low Temp 25.1ºC (77ºF)
Min Temp 34.5ºC (94ºF) Min Low Temp 21.5ºC (71ºF)
Average High Temp 39.3ºC (103ºF) Average Low Temp 24.1ºC (76ºF)
Total Rainfall 42.7mm (1.68ins)
Animal Sightings January 2016
Greater White-lined Bat
Western Red Bat
White-throated Capuchin Monkey
Central American Squirrel Monkey
Mantled Howler Monkey
Central American Spider Monkey
Alfaro’s Pygmy Squirrel
Central American Agouti
Tome’s Spiny Rat
Striped Hog-nosed Skunk
Bare-throated Tiger Heron
Golfo Dulce Anole
Mediterranean House Gecko
Central American Smooth Gecko
Central American Whiptail
Barred Forest Racer
Green Parrot Snake
Black and Green Poison Arrow Frog
Golfo Dulce Poison Arrow Frog
Fitzinger’s Rain Frog
Stejneger’s Dirt Frog
Red-eyed Green Tree Frog
Savage’s Thin-fingered Frog
Philip Davison is a biologist, writer and photographer based in Costa Rica.
Thursday 28th January 2016
Stay Behind the Barrier
Black and yellow is the most visible color combination that exists. It follows that any creature sporting patterns in this visually obvious blend might not be trying to conceal itself. Bees, wasps and hornets are generally striped in yellow and black. Many poisonous spiders, butterflies and caterpillars are decked out in the same fashion. If they are not trying to hide then they are making themselves obvious, for whatever reason they are telling you to stay away. This strikingly acute combination of color is known as aposematic coloration or warning coloration. Humans use it too in the form of black and yellow striped tape to keep people from getting too close to a dangerous situation.
In the area of Matapalo these colors can be frequently seen and encountered throughout the forest. Flying along the forest rides and around the nectar giving bush Lantana camara in gardens are the brightly colored Heliconiids or longwinged butterflies. One of the most common of these is Heliconius sapho, its yellow banded velvet black wings beating slowly interspersed between periods of short glides as it makes its way down the trails. This aesthetic beauty is telling potential predators one thing – “STAY AWAY”.
The butterfly is unpalatable and what makes it unpalatable is the fact that it is packed with cyanide. Having a toxic defense against predation serves no purpose if the predator does not know about it. Eating one of these butterflies would result in the death of the butterfly and the creature eating it. The predators learn through experience. Once a predator, whether it be a bird or a lizard, catching and trying to feed on one of these butterflies will experience a foul taste caused by the cyanide. It spits it out and it does not take too long before the black and yellow coloration is associated with something so wholly unpleasant that anything dressed in the same colors will be avoided with a passion.
Leaf it Alone
It is not just adult Lepidoptera that use toxic defenses; many caterpillars are prone to do the same. Frangipani, (Plumeria rubra), despite being thought of as a Hawaiian plant whose flowers are used to make the leis to put around the necks of tourists, is actually native to Central America. It is the national plant of Nicaragua.
Frangipani continually flowers throughout twelve months of the year. As the sun sets the pale white blossoms give off a heavenly scented sweet perfume which drifts into the night, the aroma of which attracts night-flying hawk moths. The moths are attracted with the promise of a nectar rich feed. But nectar is energy expensive for the plant to produce so the plant cheats the moth; it reneges on the promise and produces no nectar at all. The duped hawk moth searches in vain but to no avail, the long proboscis probes into one flower after another and becomes covered in pollen. Flying from flower to flower it transfers the pollen and pollinates the plant. The moth having thus been enticed subsequently receives no reward for its labors.
There are moths that unwittingly have their revenge, the Frangipani Hawk Moth (Pseudosphinx tetrio). The eggs of this moth are laid on the undersides of the Frangipani leaves. Upon hatching the caterpillars are very small, only 10 – 15 mm. They won’t stay that way for long. After consuming their own egg shell they set about consuming the leaves with gusto. The caterpillar is a committed eating machine; it turns plant tissue into animal tissue at an incredible speed. They can almost be seen to grow day by day.
The last part of the leaf to be eaten is the stalk. If damaged the stalk leaks a stiff white liquid rich in alkaloids. The alkaloids are very toxic and would normally deter anything from consuming the leaf. The Frangipani Hawk Moth caterpillars store the alkaloids in their bodies making them in turn highly toxic. Once more that information needs to be relayed to any potential predator to save both parties from harm. The vividly black and yellow hoops with a flash of bright red head, tail and legs should serve the purpose very well. It appears to do so as these caterpillars feed in full view both day and night on the very naked limbs of the Frangipani.
Within little more than a week the plant will be denuded of leaves and the caterpillars will have increased to a very stout 60 – 70 mm. Should more plant tissue be needed to complete the larval stage before pupation then the caterpillars set about consuming the rubbery branches of the tree. One night, as if by magic, all the caterpillars will have disappeared, retiring to some secluded nook or cranny to pupate before emerging in the future as a relatively drab moth which will mate and start the process over again. Although the Frangipani may look a little forlorn in its leaf denuded state, it really doesn’t take long for it to produce fresh growth, in fact quite often on parts of the plant as the caterpillars are still feeding.
Beware a Colorful Meal
Spiders might not be that easy to find but once you start to look they are everywhere. In common with many other forms of life, the species richness and diversity of spiders is huge. More obvious than most are the orb weaving spiders, the webs of some species traversing large expanses between trees. However there are many smaller spiders with consequently smaller webs. One of the more distinctive of these is the Arrow-bodied or Spiny-bodied Spider, (Micrathena sexspinosa). Either name is appropriate and speaks for itself.
The body of the spider has an array of spines and thorns which in itself should be enough to discourage any potential predator. But sometimes physical defenses can be overcome. The spider has invested in a second insurance policy – a foul-tasting chemical defense. As with the above butterflies and caterpillars there is no point having that means by which to avoid predation if the predator is oblivious to its existence. So once again aposematic coloration comes into play, the spider is dressed in a black and yellow checkered pattern.
Any naive bird or lizard that ignores the warning signs and tries to eat the spider will end up with the spider jammed in its bill or mouth by way of the spines and thorns. All the while the spider issues from its skin a nasty tasting secretion that the unfortunate predator has to endure while trying to remove the spider from its bill or mouth. Once the cause of the vile experience has been eliminated then the bird or lizard will probably never attempt to eat anything black and yellow again.
Tiny Timid Tigers
For the last example of black and yellow aposematic coloration we turn to the hymenoptera, more specifically the ants. Ants like spiders may not at first be as obvious as mammals, birds and butterflies but take the time to look at little more closely and they most certainly are there. Leaf-cutter Ants are hard to miss, their long winding ribbons of green cut leaf fragments running like verdant rivers across the forest floor. Army Ants likewise when in a foraging frenzy move in fronts upto sixty feet across appearing as an almost large black plastic sheet being pulled across the forest floor, its intent being the slaughter and butchering of all small forms of life unfortunate enough to not be able to escape from its path. Noisy excited attendant birds and the hum of parasitic flies usually herald its approach.
But rather than these mass movements there are many other ants that occur in smaller numbers. Seen walking down tree trunks, along branches and roots in small lines like kids playing follow the leader are distinctive black ants with golden bands, the Tiger Ants, (Camponotus seriseivestris).
Tiger Ants are closely related to the Carpenter Ants and share the same life history as general foragers taking nectar, seeds and fruit from plants. They attend aphids and certain Lycaenid caterpillars for honeydew as well as taking small creatures either dead or alive. They live in colonies in hollows within dead or living trees but in much smaller numbers than Leaf-cutter or Army Ant colonies.
The name Tiger Ant conjures up visions a seriously ferocious adversary capable of doing limitless damage to any unsuspecting tourist that accidently puts his hand upon them. In actual fact they are harmless, most certainly to humans, the name referring to the coloration rather than their nature. They do however have a means of defense if disturbed. The aggravated ant will turn its abdomen between its legs so the rear end is facing forwards and then it will shoot a jet of formic acid towards its aggressor. Many ants indulging in the same defensive strategy will generally deter the cause of its ire to retreat to a safe distance.
Philip Davison is a biologist, writer and photographer based in Costa Rica.