No change in the weather this week. We have had another seven days of hot, sunny weather. There were two days when the clouds had formed and the sky remained overcast but no rain resulted although the temperatures plummeted from 104⁰F to 96⁰F.
The butterfly numbers are increasing but still way below what would be expected for this time of year which is normally the peak of butterfly activity. Around the pond at night, the Savage’s Thin-fingered Frogs are starting to gather in greater numbers. The pond is the last remaining damp area on site. The flowering period for many of the trees has finished and now some of them have started fruiting.
The major excitement this week has been the presence of a female Puma, (Puma concolor). She had been seen in several different locations around the grounds. The high-pitched barking alarm call of the Spider Monkeys is always an indication of where the cat is passing by. One day, as the sun was setting, the alarm calls of agitated monkeys and agoutis started the fill the air. The cat was on the prowl.
She left the cover of the forest and walked through an open garden. That is where I spotted her. She was in no hurry and it was patently obvious that she could see me. She crossed the driveway and made her way into some dense vegetation. The monkeys settling down in that area for the evening were suddenly stirred into action and more alarm calls began to build eventually reaching a fever pitch.
She emerged from the tangle of dense vegetation and slowly walked toward the edge of the cliff overlooking the ocean. An Agouti that was in the same vicinity saw the cat, let out a loud shriek and ran off with its hair stood on end. The cat immediately looked alert but then just as quickly lost interest. She sat down and started to clean herself before lying down for a few minutes. She then rose to her feet, turned her back on me and walked off into the rapidly darkening forest.
There was another predator that I managed to get very close to this week. Very close. While I was out conducting my butterfly counts I found a juvenile Broad-winged Hawk, (Buteo platypterus), sitting on a low cut tree stump on a trail through an open area of forest. It was an ideal opportunity to take a photo. I fully expected the bird to take off and fly away but it remained where it was and just looked at me. I approached closer and closer but very slowly, each time taking a photo. Eventually I ended up lying on the ground within touching distance but the bird never even flinched. I kept a wary eye to my surroundings as it was not beyond the possibility that the parent birds would be keeping watch and attack should I get too close but nothing happened.
Broad-winged Hawks are migratory throughout North, Central and South America. They tend to hunt in the understory of the forest from where they swoop down and take small rodents and lizards from the ground. The broad wings and short tail are a good visual identification feature.
A New Passion For Flags
Along the forest trails there are several species of Passion Vine currently in flower but this week I found one species that I had never seen before. I returned with the camera and took photos for the record and to identify this new species. –
There are sixteen species of Passion Vine to be found in the forests of the Osa Peninsula. One is seen throughout the year at Bosque del Cabo Rain Forest Lodge, the Scarlet Passion Vine, (Passiflora vitifolia). It is hard to miss the bright red flowers suspended on thin, fleshy, green stems that grow up from the ground and entwine the vegetation. Two others flower only occasionally.
The new species, Passiflora pittieri, is normally found in primary forest but at the top of the canopy or in light gaps. The flower is very distinctive with its pale cream petals and a corona of yellow-tipped orange filaments and pink-flushed anthers. This one appears to be insect pollinated as I could see bees visiting the blooms.
The leaves of this species are highly cyanogenic. When physically damaged they release cyanide which would normally deter most creatures from eating them. But where there is a system then there is a way round the system. There are many species of longwing butterfly the larvae of which feed on the leaves of various species of passion vine. The larvae have an enzyme that allow them to sequester the cyanide molecule and use it in turn as a toxic defense. The caterpillars can only eat the young leaves as the older leaves will have become too unpalatable.
Another insect associated with passion flowers are the flag-legged bugs. These phytophagous, or leaf-eating, members of the Order: Hemiptera, Su
border: Heteroptera and Family: Coreidae can usually be found clustered around the flowers of passion vine. Their rearmost legs have a large expanded flat and colored section.
If a predator approaches a Flag-legged Bug, then the insect will wave one of its two brightly colored expanded rear legs. This provides a target for the attacker which will end up with little more than a leg for its efforts while the bug will have flown away. Many Flag-legged Bugs will be observed with either one or both rear legs missing.
The Pit of no Escape
This time of year with the ground having become very dry and friable, there are many small crater-like pits that have appeared all over the trails. It would appear as if a miniature meteor storm had hit the area. Further investigation, more particularly by disturbing the sides of the crater wall, will result in small grains of sand erupting upwards towards the source of the disturbance. Buried and hidden at the bottom of the pit is a larva of an insect closely related to Lacewings and Owlflies, the Antlion, and it is this larva which is responsible for throwing the sand grains.
The Antlions belong to the Family: Myrmeleotidae within the Order: Neuroptera. Only antlions of the Genus: Myrmelon create the pits. The larva excavates the steep-sided pit and places itself at the bottom, just beneath the surface and covers itself with the fine sand. They don’t just feed on ants, any small insect venturing within the crater rim will find itself struggling to leave. The more it struggles to climb out, the more loose material it will dislodge causing it to slip towards the bottom. The predatory larva lying in wait will now begin its performance of death to bring down the final curtain on the life of its victim.
Using the front legs the larval antlion flicks sand up at the ant desperately trying to escape the steep sided crater. This serves to drag it further down towards the bottom of the pit. When it finally slips all the way down, then the mandibles of the larva snap shut around the prey’s body. This is what I was observing. The unfortunate ant was struggling to escape the deadly grip of the mandibles but to no avail. Sharp projections on the inside of the mandibles pierce the ants body and the larva sucks the juice out of the ant. Once it has finished the remaining dry and drained carcass is flicked out of the pit while the larva awaits a fresh potential food item to enter.
Philip Davison Is a Biologist, Writer and Photographer Based in Costa Rica