Felipe del Bosque Blog Dec 6th 2010
Average Daily Temp High 83°F. Average Daily Temp Low 72°F.
Average Daily Rainfall 1.56 ins. Total Weekly Rainfall 10.94ins
Average Daily Temp High 27.5°C. Average Daily Temp Low 22.3°C.
Average Daily Rainfall 39.6 mm. Total Weekly Rainfall 277.4 mm
I had a feeling it was going to be too soon to say that the summer had arrived and so as if to prove the point, the rain came back. We had a good week or so with lots of sun and pleasantly warm temperatures and the returning rain was not of the same ferocity or persistent as the previous seven months. The grounds of Bosque del Cabo were drying out quite nicely, no more deep puddles and running water on the trails, now just sticky red mud. With the soft earth, it is still possible to see what has gone before; Pumas, Peccaries, Agoutis and Coatis. It is also of an advantage to have some rain after an extended dry period to keep the vegetation green and the moisture loving creatures such as frogs happy.
The exceptionally wet conditions can be directly attributed to a “La Niña” event. According to the figures presented by N.O.A.A. the Eastern Pacific surface waters have become much colder than usual. The result of this in terms of Central American weather is enhanced rainfall. “La Niña” is an atmospheric phenomenon that occurs with a cycle of once every 3 – 6 years. It can persist for up to 3 years and can have a major effect on atmospheric winds. The current event is expected to intensify and continue on into the spring of 2011.
This week started off as a good snake week. I was required to remove and relocated a number of Terciopelos from various points around the grounds. This in itself is an unusual situation as they normally nocturnal inhabitants of the creek beds. One group of visitors had a very young Brown Blunt-headed Tree Snake in their house which I returned to the forest. These are harmless snakes but it is not everyone’s desire to share their abode with a snake harmless or not.
On one trip through the forest we were greeted by those heralds of Army Ant foraging swarms, the Grey-headed Tanagers. Standing silently on the path we were then treated to a whole host of birds excitedly taking the scattered insects fleeing from the ants, only to be caught by the avian predators; Buff-rumped Warbler, Chestnut-backed Antbird, Scarlet-rumped Cacique, Little Tinamou, Wedge-billed Woodcreepers, Tawny-winged Woodcreepers and even a Blue-crowned Manakin were all partaking of the easily available food supply.
I had recently been seeing a lot of fresh Collared Peccary tracks in the soft mud on the Zapatero trail. One morning as I was coming down the stairs to the trail head, there was a small herd of about 8 or 9 animals heading out of the trail. Several of the guests to the lodge have been seeing some family groups of peccaries around the grounds too.
While out on one of the Sunset Tours, there was the usual mixed collection of spiders, frogs, toads and snakes but on this occasion, something else caught my eye. I saw what I first thought was a small rodent running up a plant stem. On closer scrutiny it was a very pretty little Mexican Mouse Opossum, (Marmosa mexicana). We also saw a Virginia Opossum, (Didelphis virginiana), on the same excursion, but unlike its unsavory looking larger relative, the mouse opossum is a rather more endearing creature with a rich tan pelage with a cream underbelly and a dark mask covering the eye areas.
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.
The Brown Blunt-headed Tree Snake, (Imantodes cenchoa), is commonly found throughout Costa Rican forests. It is a nocturnal snake that specializes feeding on sleeping lizards. They can reach 4 or 5 feet in length but the most striking feature of this snakes physical appearance is the long pencil thin body, a very narrow neck and wide head with forward facing bulging eyes.
This snake is highly morphologically modified to feed on diurnal lizards, such as various species of Anoles, which at night lie in slumber at the tips of leaves. Anything approaching the lizard will disturb the vegetation and alert the somnolent reptile of the predator’s presence. At this point it jumps away and hopefully escapes.
Being so thin and bearing little weight, the Brown Blunt-headed Snake can move through branches and twigs without causing any movement. The triangular shape to the body and the large dorsal scales allow it to reach out a third of its body length from the branch supporting it. It has that wonderful forked tongue, which is an acute sense organ designed to detect parts per million of scent particles in the air. It also has those two huge eyes which cover a large percentage of the head. They face forward and can give a sense of depth perception, essential for the accuracy of a lightning quick strike that will follow. The unfortunate victim is snatched in its comatose state from the leaf, wrapped in a serpentine half-nelson, constricted and consumed whole before it even knew what hit it.
The eyes of the snake bear some further scrutiny if only to appreciate the cryptic coloration that along with the markings of the snake’s body serve to blend it perfectly into the background. It now becomes invisible to both its predators and prey.
One night when I went back to my cabin I was greeted by the presence of a Rain Frog, scorpion and Leaf-mimicking Praying Mantis all on the wall to the side of the door. I bagged all three separately with the intention of photographing the following day.
Fitzinger’s Rain Frog, (Craugaster fitzingeri), is a totally terrestrial frog. They don’t go back to the water to reproduce. They pair up and lay their eggs in amongst the leaf litter, only 10 – 30 large yolk filled eggs. The whole process of development takes place within the egg, there is no free swimming tadpole stage, and approximately 8 weeks later a tiny little frog, a copy of the adult, will emerge.
Text and Photographs are taken from the forthcoming book:
The Natural History of Bosque del Cabo by Philip Davison
Species List for the Week
Central American Squirrel Monkey
Mexican Mouse Opossum
Great Crested Flycatcher
Southern Beardless Tyrannulet
Brown Blunt-headed Tree Snake
Central American Smooth Gecko
Mediterranean House Gecko
Golfo Dulce Anolis
Black and Green Poison Arrow Frog
Red-eyed Green Treefrog
Fitzinger’s Rain Frog
Stejnegers Dirt Frog
Rough-skinned Dirt Frog
Yellow-trumpet Vine flowering
Monkey Comb Tree fruiting
Dutchman’s Pipe Flowering and Fruiting