Pit Vipers! Part 2: Bothrocophias microphthalmus or Small-eyed Toad-headed Pit Viper

Bothrocophias microphthalmus on the side of the trail in the Rio Zunac Reserve. Photo: Lou Jost/EcoMinga.

Yesterday I went with two friends from the Fundacion Cambugan to spend the day in our Rio Zunac Reserve. About half an hour into the hike, though, one of my friends (who was walking just behind me) jumped backwards with a shout. I turned around to see her pointing to a very powerful pit viper sitting between her and me, right next to the trail where I had just walked. I must have nearly poked it with my walking stick when I walked past….

Can you spot the pit viper? Click to enlarge. Rio Zunac Reserve. Photo: Lou Jost/EcoMinga.

It didn’t move at all. It didn’t even flick its tongue. It was the deadly pit viper Bothrocophias microphthalmus, a short stocky snake that looked like it was made of pure muscle. The venom of this species is even more damaging than the venom of the feared fer-de-lance (Bothrops asper). Campbell and Lamar, in their book, The Venomous Reptiles of the Western Hemisphere (2004), note that a related Ecuadorian species, B. hyoprora, can kill a dog in two hours and a child in seven hours. That was the gentler of the two species…they write that the species we had in front of us, Bothrocophias microphthalmus, “appears to have especially toxic venom” and “Preliminary studies suggest that the venom of B. microphthalmus is poorly neutralized by commercially-available antivenom.” Not only does it have potent venom, it also has very long fangs. A very scary creature.

Bothrocophias microphthalmus head. Photo: Lou Jost/EcoMinga.

We carefully walked around it and continued our hike, but we couldn’t get it out of our minds that we’d have to pass him again on the way out. If he changed his location to denser vegetation or under a trailside rock, we might accidentally provoke him to strike before we could see him. Our best chance would be to cross while he was still close to his original spot. So we turned around early, and when we got to the spot, he was not visible. I walked forward a few inches at a time, all senses sharply focused on the ground. Finally I found him again, safely off the trail, and we headed home with the special joy that comes from having just dodged a bullet.

Bothrocophias microphthalmus in his new spot. Photo: Lou Jost/EcoMinga.

This wasn’t the first time the camouflage of B. microphthalmus had fooled me. Ten years ago or so, in what is now our Rio Anzu Reserve, I bent down in dense vegetation to examine a little terrestrial orchid, when my friend Stig Dalstrom pointed to one of these snakes sitting coiled right there next to me. A tiny change in the angle of my approach to the plant, or in the choice of position of the snake, and the day might have ended differently.

Bothrocophias microphthalmus in the Rio Anzu Reserve. I almost stepped on this one too without seeing it. Photo: Lou Jost.

The same thing happened to me in Costa Rica, where I and one other person unknowingly walked right over a fer-de-lance in the middle of our trail–the third person in line saw it and screamed, probably saving herself or one of the other tourists in the line behind her. I guess a birdwatcher like myself makes a poor jungle guide….Luckily the snakes themselves are usually fairly lethargic. When I was in Costa Rica working as a guide, I had one tourist actually sit on a fer-de-lance without getting bit! On the other hand in the same area another fer-de-lance once came at me from a long distance away, striking wildly. Each snake is an individual.

I was surprised to see B. microphthalmus in our Rio Zunac Reserve yesterday. I had never seen it there before. However, on a recent trip there I did see two very large Clelia clelia individuals. These snakes are specialists in eating other snakes, especially poisonous ones, and seeing two big Clelia on the same day got me to thinking that there must be an awful lot of unseen snakes for them to eat here….

Clelia clelia, a snake-eating snake, in our Rio Zunac Reserve. Note the very large head scales. That’s a good way to tell other snakes from pit vipers, who always have fairly small scales on the top of the head. Photo: Lou Jost/EcoMinga.

Note added Dec 13 2014: I sent these photos to biologist Jerry Coyne who posted them on his website, “Why Evolution is True”. Go there for other people’s snake stories in the comments.

Note added Dec 28 2014: Searching through our archived snake pictures, I found some photos of the juvenile of this species, taken by reserve manager Juan Pablo Reyes and “Keeper of the Wild” guard Jesus Recalde. The juvenile is a beautiful bright yellow! These were taken in our Rio Anzu Reserve:

Bothrocophias microphthalmus juvenile, in our Rio Anzu Reserve. Photo: Juan Pablo Reyes and Jesus Recalde/EcoMinga.

See also Pit Vipers! Part 1: Bothriopsis:

Bothriopsis in our Rio Zunac Reserve. Click image to enlarge. Photo: Luis Recalde/EcoMinga.

Lou Jost
http://www.ecominga.com
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