Snakes in Costa Rica

Of the 139 species of snakes in Costa Rica only 22 species are venomous. The biggest buzz however is always made about poisonous snakes. Many myths and misunderstandings exist in Costa Rica and people tend to kill them just precautiously. But even the most venomous snakes will only strike at humans if they are threatened. * 

Snakes belong to an intact eco-system. They play an important role in controlling other animal populations. Do not kill them!

Part I - Snakes with brown patterns

Boa Constrictor

Boa Constrictor
Length: up to 4.6 meter

A large and one of the most frequently seen snakes of Costa Rica the Boa can grow to over 4.5 meters length. The nocturnal hunter is also capable of swimming and lives on a diet of small and medium sized birds, reptiles and mammals. The boa first strikes at the prey with its teeth, then constricts the prey until death before consuming it whole. A bite for humans is rarely dangerous yet can be painful. The snake however is not aggressive and will only strike if threatened.

The color pattern of a Boa is highly variable yet distinctive with dark and light brown blotches on its heavy body. Besides the Boa Constrictor, which is found all over Costa Rica, there are smaller species of Boas, like the uniform brown colored Rainbow Boa, the Caribbean Annulated Tree Boa and the Garden Tree Boa in the Southern Pacific Zone.

Terciopelo / Fer-de-Lance

Bothrops asper
Length: up to 2.3 meter

The snake that accounts for most of the dangerous snake bites in Costa Rica is the Terciopelo. As Costa Ricans are awfully afraid of snakes as a whole, a lot of harmless snakes with similar pattern are precautiosly killed as well. As distinctive features of the real Terciopelo note the rhomboids on their robust body and the black stripe after the eye. The pupils are vertical and the head has a triangular shape.

There is also the non-venomous False Terciopelo which is smaller, doesn't have the large triangular head and its pupils are round.

Lyre Snake

Trimorphodon Quadruplex
Length: up to 1.8 meter

Another commonly found snake that is often killed because it's taken for a Terciopelo or other poisonous snake is the harmless and relatively slender Lyre Snake which also doesn't have a triangular head, has round pupils and the pattern on her body are dark butterfly-like blotches. They are common in the dry tropical forest of the Nicoya Peninsula. Though generally terrestrial the Lyre Snake is also a adept climber.

Jumping Pitviper / Mano de piedra

Atropoides mexicanus
Length: up 86 cm

Despite its name the Jumping Pitviper can't really leap at an attacker. The relatively common species is found in lower elevations of primary and secondary forests throughout Costa Rica. Note the dark stripe behind each eye, and vertical pupils. These snakes are extremely thick-bodied, with dark rhomboids on its dorsum.

Neotropical Rattlesnake

Crotalus simus
Length: up to 1.7 meter

Another snake with a rhomboid pattern on its dorsum. Also note the black stripes running from each eye. The Rattlesnake is relatively common and mostly found in the hot dry climate of the Nicoya Peninsula and Guanacaste. The mostly nocturnal hunter will rattle with its tail when threatened. It's a gentle hint that the snake wants to be left alone. Slowly move backwards and let the snake go her way.

Bushmaster / Matabuey

Lachesis melanocephala
Length: up to 3 meter

The largest viper in the world the Bushmaster is the most venomous viper of the Americas. Bushmaster bites are rare as the animal is shy, only striking when threatened. However there is a 75% mortality rate from the bite. Bushmasters don't occur on the Nicoya Peninsula. They are found on the Caribbean Side of Costa Rica, and the Black-Headed Bushmaster in the Southern Pacific Zone.

Above pictures of venomous snakes were all shot in a serpentarium. In the wild I never saw them. Instead I see a harmless boa or a lyre snake from time to time.

 

More: Part II - Non-venomous colored snakes
          Part III - Coral snakes

 

On an average around 600 people per year are bitten by a snake in Costa Rica. Of these only 1 - 2 people die, as in most cases the snake was not poisonous. Costa Rica's health system also provides good, country-wide supplies of anti-venom. It's far more probable to die from a traffic accident in Costa Rica as the country has one of the highest mortality rates from road accidents per capita in the world.