Costa Rican Wildlife- Part 1.
I had the privilege of going to Costa Rica in search of exotic wildlife. My trip included two very different regions, the Osa Peninsula and the highland cloud forest. This post will focus on some of the mammalian wildlife of the Osa Peninsula I saw.
Clicking on the images in this post will enlarge them for a better viewing experience.
Costa Rica is located in Central America, bounded on the north by Guatemala and on the south by Panama. Although it is a small country, about the size of West Virginia, it seems much larger than it is due to its varied terrain and the difficulties of getting from one place to another.
My trip began with a flight to San Jose, the capital city of Costa Rica, to meet the rest of the photo workshop group led by professional wildlife photographer Juan Pons.
From there, a 45-minute flight on a small plane took us to Puerto Jimenez on the southeastern shore of the Osa Peninsula.
Our base of operations was the Crocodile Bay Eco-Resort on the Gulfo Dulce, one of only four tropical fjords in the world. The lodging accomodations were in a lush tropical forest complete with lagoon that provided habitat for many species of wildlife. There were trails that we could wander in the early morning hours before heading out on each day’s excursions and after dark. While in Costa Rica, our lead local wildlife guide was the Director of Expeditions for the resort, Dennis who, himself, is an accomplished wildlife photographer.
Here is a sampling of a few of the critters that I encountered while wandering the grounds of the eco-lodge.
First, a Little about Costa Rica:
The Osa Peninsula is a 35-mile long by 20-mile wide strip of land attached to the southwestern edge of Costa Rica and situated between the Pacific Ocean and the Gulfo Dulce.
The geography of Costa Rica can be explained by a process that geologists call plate tectonics (the movement of giant pieces of the earth’s crust that act like rafts floating over a partially molten layer of rock). In fact, Costa Rica’s geologic story has a lot in common with ours in the Pacific Northwest.
Costa Rica sits on the Caribbean tectonic plate (peach color on diagram) which is drifting in a southwesterly direction while the Cocos Plate (blue), a more dense oceanic plate, is traveling in a northeasterly direction.
When two tectonic plates collide, if one is more dense than the other, it will dive beneath the less dense plate to be recycled into the earth’s hot mantle in a process called subduction. The grinding together of the two plates can cause earthquakes.
As the subducting plate descends, it melts and causes hot magma to rise forming volcanic ranges. The subduction of the Cocos Plate under the Caribbean Plate is primarily responsible for the mountainous topography of much of Costa Rica.
The Osa Peninsula started out as an island in the Pacific on which evolution occurred in isolation while it was floating along on the Cocos Plate. About 2 million years ago, it smashed into and attached to the mainland. The Osa’s long period of isolation, resulted in the evolution of many endemic species (species found no where else in the world).
Since the Osa was the last region of Costa Rica to become populated, it retains a significant amount of unspoiled primary rainforest. National Geographic proclaimed the Osa Peninsula to be “the most biologically intense place on Earth” with the world’s highest biodiversity per acre. The Osa possesses an estimated 2.5% of Earth’s biodiversity while covering less than 0.001% of the planet’s total surface area. Costa Rica has developed a strong record in environmental stewardship, and 80% of the peninsula’s rainforest is now protected, mostly as part of Corcovado National Park. Thirteen major ecosystems are found on the peninsula, ranging from sea level to about 2500 feet including mangroves, sand beaches and primary forests. There are 117 known species of reptiles and amphibians, 365 species of birds, over 120 species of mammals, and 700 species of trees. Four types of monkey, 2- and 3-toed sloths, a variety of big cats, and the largest population of Scarlett Macaws in Costa Rica are all found on the Osa Peninsula.
We went to number of locations (blue pins) on the peninsula to view the wildlife of different ecosystems.
Our first day’s excursion involved driving south from Puerto Jimenez to Matapalo in search of monkeys. This drive is not for the faint-hearted. The road is terrible requiring a high clearance vehicle. It is rutted with big potholes, rocks sticking out of the ground, and many bridges that are either too unsafe to use, or simply missing, forcing you to ford the rivers in your vehicle. This is probably why the vehicle I was riding in was equipped with a snorkel which allows you to cross deeper water than you’d be able to otherwise.
The snorkel tube runs from the engine compartment up to the top of the vehicle, allowing it to breathe without sucking water into the engine and stalling.
The next day took us to La Tarde for photographing elusive reptiles and amphibians such as poison dart frogs and vipers. The third day was an all day drive to Carate which is the best place to search for Scarlet Macaws in their native environment. This trip incorporated another lovely drive on the road to Matapalo plus we got to explore a deserted beach near Carate. On the fourth day, we visited La Perica which is owned by our wildlife guide Dennis’ family. La Perica is an area of forest that has been preserved on a palm oil growing plantation. Here our main target was the sloth although we did see some in our other explorations. Our last day on the Osa was an all-day cruise on the Sierpe River that flows through the Terraba-Sierpe Wetlands, home to a lush, mangrove ecosystem. This area has a diverse reptilian and bird population.
Primates
Four species of monkeys inhabit the Osa Peninsula, two in the Cebidae Family (Squirrel and Capuchin Monkeys) and two in the Atelidae family (Howler and Spider Monkeys).
The Red-backed Squirrel Monkey (aka Central American Squirrel Monkey) is the smallest of the Costa Rican monkeys with 9- to 14-inch long bodies and weights up to about 2-pounds.
They are colorful with a black cap, muzzle and tail tip; orange main body; and olive brown tail. Their tails, which can be up to 18-inches long, are used mainly for balance as they move through the trees on four legs. This is a very social species traveling through the tree tops in groups up to 70 strong feeding on insects and fruit. They are a non-aggressive species in which neither males nor females are dominant. At one time, these monkeys were captured and sold in the pet industry because of their non-aggressive nature. They have suffered significantly from habitat destruction throughout their range. Red-backed squirrel monkeys are found mainly in Panama and along the southern coast of Costa Rica. They are listed as endangered having a population decline since the 1970s from 200,000 to an estimated 4,000 today. The Osa Peninsula has a relatively healthy population. These cute little monkeys were my favorites of all the species.
The Central American Spider Monkey (aka Geoffroy’s Spider Monkey) is a large, long limbed monkey with a prehensile tail. The arms ending with dark hands are significantly longer than the legs.
Their tails are able to support the entire weight of the monkey and serves as an extra limb. The face usually has a pale mask with bare skin around the eyes and muzzle. These monkeys tend to sleep together in groups of 10 to 40 at night, but split into smaller groups of 2-6 during the day as they forage for fruits, their preferred foods. They will also eat leaves, flowers, bark, insects, and seeds. They move through the forest by swinging from their arms with assistance from their tail, a process called brachiation. Although they can leap from tree to tree, the most common method to transition from tree to tree is called “bridging”, in which the monkey pulls a branch from the new tree towards itself so it can climb onto it. This species requires large tracts of primary forest to survive. They are vulnerable to the effects of deforestation and capturing for the pet trade. Since they have a low reproductive turnover, spider monkeys are incapable of quickly replenishing their population numbers. They are listed as a critically endangered species.
The Mantled Howler Monkey is large and stocky with a long prehensile tail. This species is primarily black with a mantle of long yellow-brown fur on their sides. They tend to live in groups of 10 – 20 individuals that include a single dominant male and a harem of females with whom he mates.
They move through the forest canopy by walking on all four limbs feeding largely on tree leaves which they supplement with fruits, flowers and buds. Howler monkeys are a very noisy species. Their roar can be heard over several miles and serves to help different troops maintain proper territorial distances. These monkeys are fairly common and widespread from Mexico to Peru and are not considered endangered.
The White-faced Capuchin is a medium-sized monkey that is primarily black with cream colored shoulders, head, chest and a pink bare face. They tend to live in groups of 5-30 individuals.
These are the only Costa Rican monkeys that travel and forage on the ground as well as moving in the trees. They are a rather aggressive species. They will hunt cooperatively to capture squirrels, and raid the nests of birds for the eggs. They are omnivores and also eat fruit buds, flowers and fruits. Capuchins are more ape-like than the other Costa Rican monkeys. They are highly intelligent and will use tools. A capuchin has been observed to use a stick to beat a snake to death! They also collect medicinal plants and use them at appropriate times for various purposes. This species is highly adaptable to changing environments and not classified as endangered.
Sloths and Anteaters
Two species of sloths are found in Costa Rica, the Hoffmann’s Two-toed Sloth and the Brown-throated Three-toed Sloth. The two-toed sloths are the only members of their family and are related to an extinct group of giant, elephant-sized ground sloths. There are four species of three-toed sloths, but only one is native to Costa Rica. The terms two-toed and three-toed are a bit misleading as both species have three toes on their rear legs. The two-toed has only two fingers on each arm while the three-toed has three fingers. Sloth fingers and toes are equipped with 3- to 4-inch long claws which are perfect for gripping branches. I only saw three-toed sloths on my trip.
The sloth has the reputation of being a lazy, slow and stupid creature. This probably stems in part from the early French naturalist Georges Buffon, who described them as the “lowest form of existence” back in 1749.
In reality, the sloth’s lethargic lifestyle is a deliberate survival strategy that has allowed it to exist for nearly 65.5 million years. Sloths came into existence just before the dinosaurs disappeared. In a nutshell, sloths are slow-moving, nocturnal creatures that spend almost their entire lives upside down in trees.
The slowness of sloths can be attributed to adaptations that result from their diet. Sloths are folivores, feeding primarily on leaves (preferred tree is the cecropia) which are poor in nutrients, have low caloric content, and are highly indigestible. To survive with such a low intake of calories, sloths have evolved a slow metabolism, and their slow-moving lifestyle allows them to conserve energy.
This video is of one of the sloths we encountered. I shot it in real-time, not in slow motion!
The warm tropical environment in which they live is also important to their survival. Mammals, in general, are capable of internally regulating their body temperature, something that separates them from cold-blooded animals such as reptiles, and gives them an ability to survive in cold temperatures. Mammalian thermo-regulation requires a lot of energy and that energy has to come from the food they eat. Loss of thermo-regulation is an adaptation that sloths evolved. Since they live in a tropical climate which is already warm, a sloth does not have to expend a large amount of energy to keep its muscles and cardiovascular system warm. If a sloth starts to get chilled, it will move high in the tree to warm itself in the sun.
Sloths have a highly specialized muscle arrangement that makes them incredibly strong despite having 30% less muscle mass than other similar sized mammals – more muscle requires more energy consumption.
The fibers of sloth muscles have an angular pattern rather than one that parallels the length of the muscles like most other mammals. Sloth muscles work on a lever system giving them great pulling strength with less muscle mass and require less expending of energy. At birth, cubs are able to lift their entire body weight upwards with a single arm. This muscle design, however, provides little strength for pushing. A result of the sloth’s highly specialized muscle structure is the inability to push their bodies off the ground for efficient quadrupedal locomotion. Since a sloth cannot walk any distance, it stays in the forest canopy using vines to travel from tree to tree.
There are specialized tendons in a sloth’s hands and feet which lock into place making it possible for them to hang upside down for long periods of time without expending energy. They can hang motionless on branches 15-20 hours a day. This locking mechanism allows them to sleep while hanging from a tree branch without falling.
Since the sloth’s diet consists of highly indigestible leaves, their digestive system has evolved to solve this problem. The sloth has a large stomach that is divided into four chambers occupied by bacteria that help to slowly digest the fibrous leaves. Although this system is similar to that of a cow, it takes a sloth about ten times longer to digest its food. It can take up to two weeks for a sloth to digest a single meal which is the slowest digestion rate of any mammal. Again, this slow digestion rate is linked to the sloth’s low metabolism. A sloth can only eat when there is room in the stomach for additional leaves to be added, and they keep their stomachs full. A sloth’s stomach can account for up to 37% of its total body mass.
What goes in must eventually come out. A sloth will climb down to the ground about once per week, dig a hole at the base of the tree, and defecate into it losing about one-fifth of its body weight. Again, this seems to be an evolutionary adaptation. Scientists estimate that 50% of sloths lose their lives when they are on the forest floor so making infrequent trips to the ground is good for survival.
The fur of three-toed sloths has a greenish cast to it which makes them a little difficult to detect when they are curled up sleeping in a high crotch of a tree.
Each hair of the sloths coat is a hollow tube possessing a lengthwise slit. Algae grows in these hair tubes, and this is what gives the fur its green tint.
Sloth moths, whose job is to keep the algae growth in check, also live in the fur and eat the algae. It is thought that there is a mutually beneficial relationship between the sloth and the moths that colonize its fur. Some scientists believe that the reason sloths undertake the risky journey to the ground for bathroom duties is in cooperation with the moths that lay their eggs in the fresh deposit. After the eggs hatch and the moths reach adulthood, they fly up into the canopy to mate in the fur of a sloth. The ramifications of this cooperative relationship are still a mystery.
The photo above is not of an injured sloth. Rather, it shows a defining characteristic of a sexually mature male sloth. The color pattern on the back, called the speculum, is unique to each male sloth.
It was exciting to see sloths in the wild and one of the highlights of my trip.
Anteaters are the sloth’s closest relative although to the casual observer, they seem very dissimilar – sloths eat leaves while anteaters eat ants!
In fact, anteaters are not related to other ant-eating animals such as aardvarks and echidnas. The sloth and anteater evolutionarily diverged a very long time ago, last sharing a common ancestor about 60-million years ago. Sloths and anteaters, along with armadillos are members of the Xenarthra family. The members of this family are one of the oldest groups of mammals still in existence today. Some traits that the sloth and anteater have in common are the ability to climb trees, poor eyesight, a powerful sense of smell, and long, powerful claws.
Like sloths, anteaters are very unusual animals. They have evolved adaptations that aid them in their feeding behaviors. Disturbing an ant nest can be painful so the anteater has developed the ability to get in and out before the ants have time to react and attack the intruder. The anteater has an extremely long tongue that can extend up to two feet and is covered with backward-facing spines and sticky saliva to trap ants. The anteater uses its long, powerful claws to rip open a nest and snag as many ants as possible in about minute with its tongue. Anteaters can flick their tongues up to 150 times a minute snagging ants. Before the ants can retaliate, the anteater moves on leaving the majority of the colony intact. Anteaters can gobble up 30,000 ants in a day.
The Silky Anteater is a small woolly animal with a body not much larger than a hamster, typically about 15 inches long from tip of nose to tip of tail and weighing less than one pound. They have two long, sharp claws on each front foot and a prehensile tail.
The silky anteater is an arboreal species that is nocturnally active. During the day, it will curl into a golden ball sleeping in vine tangles or on narrow branches hidden in foliage. As a species, these are the least studied of the anteaters. They are seldom seen because their preferred tree is the ceiba which produces fluffy golden seed pods that serve as camouflage. We were extremely lucky to spot this silky anteater. If you look very carefully, you can see the photo is a mother with her baby. One of our native wildlife guides had never seen one in the wild before.
My trip to Costa Rica was an awesome one. If you have an interest in photographing wildlife, I recommend you check out Juan Pons’ Photo Workshops. I have yet to be disappointed in any wildlife-seeking adventure I have taken with him. The Osa Peninsula was a great place to see some interesting, and even unique, mammals. In addition, I was able to photograph many birds, reptiles and amphibians, but since this post became fairly lengthy (and you are probably now exhausted), I will do a separate one on those and also the wonderful birds of the Costa Rican cloud forest. Stay tuned for Part 2!
Resources:
- Reid, Leenders, Zook & Dean, The Wildlife of Costa Rica, A Field Guide
- The Sloth Conservation Foundation
- 10 Facts about Sloths
- 8 Facts You (probably) Didn’t Know About Sloths Anatomy
Very interesting and informative, as always! I am sad to see the data on the endangered monkeys. I am glad to know that Costa Rica has been able to figure out how to survive and maintain their forests.