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Snakes in Costa Rica

Small and colorful or big and inconspicuous

Many people are afraid of snakes and therefore don’t travel to Costa Rica. In most cases snakes are good at hiding so you rarely see one unless you are specifically looking for the animals. The greatest respect is due to the country’s large and poisonous snakes but if you stay on the designated paths you will rarely come across a snake. If, for example, you are specifically looking for a beautiful lance viper, you should definitely take a guided tour because the local tour guides know best from their experience where the animals like to stay and hide. 

Costa Rica is home to 137 different species of snakes, about 5% of the world’s species. With over 100 species, the colubrids family is the largest group. The majority of Costa Rican snakes are non-venomous and usually quite shy. Many are only about 8 inches long but there are also snakes over 10 feet. 

There are 6 species of large snakes including the infamous Boa Constrictor which grows up to 10 feet long and can weigh 45 pounds. Like the colubrids, boa constrictors do not produce poison, they kill their prey by strangulation which is where the term “constrictor” comes from. In addition to the colubrids and giant snakes, there are also 22 different types of poisonous snakes. The most dangerous and also the most widespread in Costa Rica is the fer-de-lance.

Venomous Snakes

The fer-de-lance is the most dangerous of Costa Rica’s 22 venomous snake species because it has a rather irritable character and it often stays in the vicinity of human settlements. Thus, the probability of encountering a fer-de-lance is greater than any of the other species. The so-called bushmaster has a similarly life-threatening and large amount of poison as the fer-de-lance but lives far away from people in dense primary forest and has a rather calm character. These two snake species belong to the pit vipers along with 14 other species. Most of the other venomous snake species are not actually dangerous to humans and there is no life-threatening injury from a snake bite. 

By far the strongest and most effective poison is found in the elapids. There are a total of five species in Costa Rica two of which live in the sea, the coral snake and the sea snake. Each of these five species has an extremely potent neurotoxin that can be deadly to humans even in tiny amounts.

We can reassure you, however, most of the time there are no fatal incidents with these snakes. Annually 500 to 600 bite accidents with poisonous snakes are reported in Costa Rica but thanks to the good medical care in the country they are only fatal in just under 1.5% of cases. The special antivenoms are developed and manufactured directly in Costa Rica. The victims are mostly plantation workers who are in increased danger due to their constant work in nature. Tourists, on the other hand, are rarely bitten by snakes. If a snake feels threatened by humans the smaller and faster snakes usually flee into the safe thicket. Many rely on their good camouflage and others immediately show a clearly recognizable and species-specific threatening behavior. For example, the rattlesnake rattles its tail warning its attacker not to come closer. Should the attacker come closer despite the warning, the snake bites.

About 5% of the world’s snake species live in Costa Rica, but don’t worry, most of them are non-venomous and completely harmless, however, the rattlesnake is not one of them. It is one of the 22 venomous snakes found in Costa Rica. The Tropical Rattlesnake is part of the viper family and, like all vipers, can be recognized by its triangular head and by its rattle tail which it shakes like a rattle when threatened. Tropical rattlesnakes are up to 6 feet long and as small as 2.5 feet. Their color variance ranges from grey-brown to earth-colored, to greyish, yellowish and reddish. Each individual usually looks different which is why no precise description can be made. A black diamond band usually runs across their backs. The snake has a slim body compared to its head. When the snake looks into the light, its pupils narrow into vertical slits.

Tropical Rattlesnakes are crepuscular and nocturnal. During the day they hide in burrows of small animals or tree cavities. Unlike other snakes, the rattlesnake does not hibernate due to the consistently warm tropical air. They live mainly in low-growth and rocky dry regions but can be found in different areas. It is also an occasional guest near human settlements but biting accidents are rare. If accidents do occur, however, then a hospital should be visited as soon as possible because the venom of the tropical rattlesnake is the most poisonous among the rattlesnakes.

Among the 22 venomous snake species in Costa Rica are the pit vipers. The most important species of pit vipers are the “Fer-de-Lance” and the “Eyelash viper“. Both species can be recognized very quickly by their triangular head.

The Fer-de-Lance has a brown color with diagonal stripes. It grows up to 6.5 feet long and its main diet consists of small mammals and sometimes opossums or agoutis. They are found on the ground most of the time but can also live in trees. The lance-heads are nocturnal so an encounter with this snake is relatively rare. Unlike many other snake species lance vipers do not lay eggs but give birth to about 40 live young.

Despite their nocturnal activity most snake bites in Costa Rica are from the fer-de-lance. Most bites from this snake are “dry bites” that is, non-venomous bites because the fer-de-lance would need several days to reproduce its venom. Without venom, it is difficult for this small snake to catch prey. So they save their venom to satisfy their hunger with smaller animals. The fer-de-lance only attacks humans when it feels threatened. Since it knows that humans are too big to eat it saves its venom for prey animals. So most venomous bites are not from large experienced snakes but from small or medium-sized ones which are quite inexperienced. The venomous bite of this snake is very dangerous to humans because it contains enzymes, low molecular weight polypeptides, metal ions, and other components that are poorly understood. Nevertheless, the bite of this snake is far from a death sentence. If you get to the hospital fast enough, you have a very good chance of recovery. In Costa Rica, hardly anyone dies from a snake bite these days.

You can protect yourself from snake bites by wearing sturdy shoes, staying on the paths, walking carefully through the jungle and never reaching under stones or into holes that are not visible. 

Constrictors

Constrictor snake is a collective term for snakes that, unlike venomous snakes, kill their prey by strangulation. Well-known species include boas, pythons and many species of colubrids. After the bite the snake wraps itself around the body of its prey and squeezes it tighter with each exhale so that the animal’s blood does not flow back to the heart and no more air can flow.

The snake does not suffocate its victim, as was previously assumed, but causes cardiovascular failure. The constrictor can feel when the heart of its prey stops beating and then swallows it whole. Since most constrictors are as good as blind they recognize potential prey by their tongues. With their extremely sensitive tongue they recognize scents from animals that are in their environment. They can also see heat in the form of infrared radiation. Well-known constrictors in Costa Rica include the boa constrictor and the Mexican burrowing python.

The boa is a beautiful snake with marvelous markings. It is fairly common in Costa Rica and not impossible to see, however, you won’t see them unless you look for them. They often visit the chicken coops of the campesinos (farmers) and unfortunately you see a lot of them dead on the street. But if you manage to find a living boa you can call yourself lucky.

The boa constrictor, also called the red-tailed boa or common boa, is probably the most well-known snake from Central America. With a huge length of 3 to 13 feet it is also the largest of them. Boas are found throughout Costa Rica and are comfortable in trees as well as on the ground. As a rule, they prefer coasts, semi-deserts and humid rainforests at altitudes of up to 1,500 meters above sea level. 

Boa constrictors have a huge variance in color and body composition. Boa colors can range from white and brown to red and black but all boas have dark contrasting saddle patches on their backs. An extraordinary feature of the boa is shown by its scaly skin which can change color similar to the chameleon. Depending on the temperature their skin turns lighter or darker so a boa lying in the shade is not easy to recognize. 

Boas are active at dusk and at night but sometimes they are seen sunbathing near their hiding places during the day. If the boa feels threatened, it hisses. A bite does not threaten death because boas are not poisonous, but a bite wound can be quite painful. The boa constrictor feeds mainly on birds, lizards and mammals which it usually attacks from a branch and then strangles. They crush their prey so hard that a circulatory collapse sets in. This process can sometimes take up to 16 minutes and costs the snake a lot of strength and energy. So that it does not use up too much energy, the boa feels the heartbeat of its prey and stops exactly when it is no longer there. 

There are certain mating times for king boas when the female releases special scents which the male animals then follow in a targeted manner. After about 130 days the boa gives birth to its young alive with a litter size of about 10 to 60 young. The newborn snakes weigh around 1.7 ounces at birth, are around 20 inches long and are surrounded by a thin egg membrane. The young snakes stay in trees for the first months to years with the mother protecting her offspring for a short time and sometimes encouraging them to crawl with her snout and helping them out of the egg shell. After that, the boys are on their own.

The mexican burrowing python is a species of snake native to Central America and the only species of the Loxocemidae family. It can grow up to 4 feet long and it looks like it has no neck because of its powerful body. The snake can appear dark brown to gray-brown and shimmers purple when illuminated by the sun. Their abdomen is usually dark in color. The mexican burrowing python has a conspicuously large head scales compared to others in its genus.

Mexican burrowing pythons are found from northern Costa Rica to the Pacific coast of Mexico and prefer moist to dry forests at altitudes of 0 to 600 meters above sea level. Here the python can simply burrow through fallen leaves and damp soil to either track down prey or build a shelter. These snakes often spend a few days completely underground. In order to be able to move perfectly in the ground, the python has a pointed head and small eyes. The mexican burrowing python feeds mainly on small mammals or small reptiles and their eggs. It kills its prey by strangling, because the pythons do not have fangs. The mexican burrowing python is an egg-laying snake. Once the snake has laid eggs, these must then be hatched. 

Non-venomous Snakes

Most of the non-venomous snakes in Costa Rica are colubrids. With around 100 species they form the most species-rich family of snakes in Costa Rica. Most colubrids are slender with fairly large scales covering their bodies. If you spot a snake it usually looks at you with big eyes unless you come across one of the burrowing species which have smaller eyes. Most snake species are harmless because they do not have poisonous fangs. 

As a rule, snakes feed on small mammals, birds and fish. They are nocturnal hunters and if you come across a colubrid during a day hike they are usually sleeping in tree hollows or sometimes in the beams of a hiker’s hut. If they are out at night they might catch a sleeping hummingbird, hardly imaginable when you think of the nimble flight artists that you meet during the day.

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