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biodiversity Introduction non avian organisms

Snakes and Birding in Costa Rica

Recent conversations and inquiries about snakes (especially the venomous ones) followed up by a close encounter with a Fer-de-Lance has prompted me to finally write “the snake post”. Like many birders, although I focus on the feathered, I am also interested in many other aspects of nature (I almost said, “the natural world” but how could it be anything but natural). Among the myriads of life forms on our precious planet, snakes rank pretty high up there as creatures I would love to see more of and I admit that I keep a casual world snake list (my best species are Anaconda and Eastern Hog-nosed) but the list is pathetically short because I hardly EVER see any of the 130 plus species found in Costa Rica. While tromping around the tropical woods, I often wonder where they all are and you probably will too unless you spend all of your time herping instead of birding (and even then it might be easier to see birds). In actuality, snakes are probably somewhere in the vicinity no matter you go in Costa Rica; they just don’t want to be seen. Since they are easy to catch and have such a wide spectrum of predators that include coatis, peccaries, a variety of birds, other snakes, and unforgiving people, they have more than enough reasons to remain hidden. Some have even evolved to hide in plain sight with the help of fantastic camouflage; a trait that despite being very impressive, tends to promote anxiety and paranoia among guides and field biologists. One starts to get a little paranoid because the more time one spends in tropical habitats, by sheer probability, the more likely it is that one will be too close for comfort to a Fer-de-Lance. Realizing that that they are common and incredibly camouflaged doesn’t help either even though there are plenty of stories of people walking close to or even grabbing this highly venomous snake without getting bit. As of this past Sunday, I can now add my own encounter with a Fer-de-Lance to the long list of stories with happy endings that involve this infamous pit-viper.

I was at Quebrada Gonzalez with a client and my driver for the day and we were doing the loop trail behind the station for the second time (I often find different species doing the trail more than once, the additions on Sunday being White-whiskered Puffbird, Streak-chested Antpitta, and Spotted Antbird). Earlier on, during our morning walk, one of the rangers had passed us on the trail and had casually mentioned that he was going to use the long pole he was carrying to remove a large Fer-de-Lance from the path. Being occupied with staring into the trees on our search for birds, we didn’t see him move the snake but didn’t see the Fer-de-Lance that first time around. Although he had lifted it off of the trail, he apparently didn’t relocate it far enough away from the path because much to our nerve-racking surprise, it came back in the afternoon. Despite knowing where the snake had been hanging out and watching where I was stepping, I didn’t see the 5 foot serpent until it was practically underfoot. Its camouflage worked so well that I only noticed it because it was kind enough to move off of the path before I stepped on it. Although it was rather alarming to find that I didn’t see the snake until it moved, at least I can say that I am pleased with my instincts and reaction time. As soon as I perceived motion near the ground, I moved so fast that the only thing I recollect is possibly flying for about ten feet while exclaiming, “Stop! Snake! Snake on the trail! Don’t move!” After uttering a few other choice words to release the tension, I quickly calmed myself down (kung-fu birding at its best), and noticing that Linda and Janet could make a safe detour around the snake, directed them past the scaly beast. Although I didn’t notice exactly where the Fer-de-Lance had been at the start of this encounter, it ended up moving entirely off of the trail and took up a defensive posture.

See if you can find the snake below!

Here is a close-up of the head.

And if you had trouble finding the snake, here it is outlined.

It was pretty big and I am very lucky that it didn’t strike. Its reaction, though, is consistent with most other encounters that I have heard about. The few people who have gotten bit in Costa Rica have not been birders. They are usually people who picked one up, were cutting low-lying vegetation with a machete in a garden, or were walking at night along a forest trail in bare feet (this from a Bribri woman who told me that she got bit during a full moon and so of course her foot aches at every full moon). Although it sounds like the Fer-de-Lance typically reacts the way this snake did, that doesn’t mean that you should ever get that close to one! I take this encounter as a warning of sorts and in addition to never walking where I can’t clearly see the ground, will also scan the trail 10 meters ahead with binoculars to specifically check for snakes, and will watch 2 meters ahead of where I am walking. If I had done this, I am pretty sure that I would have seen the snake before almost stepping on it because I was only checking the ground directly beneath my feet. Rubber boots probably also add some protection (I usually wear those anyways).

It was actually a bit unusual to see a Fer-de-Lance deep inside the forest as they are much more common in second growth, grassy areas, at tree-fall gaps, and along streams. Be especially careful near marshy areas or other habitats that harbor lots of frogs because contrary to what has often been said about this infamous viper in books and TV shows, at least on the Caribbean Slope, they appear to be strict connoisseurs of the “grenouille”. I found this out last year when speaking with a naturalist who lives in the Reventazon Valley and is probably more of a herper than a birder. Over at least twenty years, in checking the stomach contents of at least a 100 Fer-de-Lances, every single one had fed almost exclusively on frogs no matter what size the snakes were. He also said that Bothrops asper were very common in fields with tall grass-keep that in mind next time you want to leave the trail! On his property, the venemous snakes that were taking larger rodents were Bushmasters. Much rarer and harder to find than Fer-de-Lance, on the Caribbean Slope of Costa Rica, they appear to be restricted to mature foothill forests (such as that of Quebrada Gonzalez) rather than in lowland forest. These observations also reflect my own experiences in Costa Rica and southeastern Peru. When I worked at the Posada Amazonas lodge in Tambopata Peru, during occasional explosions of mouse opossum and rodent populations, it was never Bothrops that suddenly showed up but Boas and Bushmasters (although it still took a lot of effort to find either of those). Regarding Bushmasters, they also blend in with the leaf litter but are more likely to occur near a log or base of a tree than on the trail itself (unless the log is lying across the trail). They are also pretty darn rare in Costa Rica so it is very unlikely that you will run into one (although rangers have told me that this species is untypically common at Hitoy Cerere).

Bushmaster or “Matabuey” at the Monteverde serpentarium.

Other snakes to watch our for on the ground are Jumping Viper (sounds scarier than it is), two species of Hog-nosed Vipers, and the Tropical Rattlesnake. The first three are rather small vipers that blend in quite well and could occur on a trail. Although I haven’t seen either of the Hog-nosed Vipers in the wild, I had a run in with a Jumping Viper at Bijagua that left me pretty frazzled. We were both in a hurry and like pedestrians on a crowded sidewalk, nearly ran into each other. Although I was the only one that jumped, I think it was just as startled because the viper opened its mouth and hissed at me. Hoping that it would continue on its way if I left it alone, I backtracked and birded for about twenty minutes before walking back up the trail. Much to my dismay, it hadn’t moved an inch and even knowing where it was, I still didn’t see the two foot snake until I was within ten feet of it. Oh yeah, just to make sure that I couldn’t miss it, the unfriendly serpent also hissed again. I ended up lifting it off the trail with a very long stick (which it struck repeatedly), and was hissed at as I walked past the snake even though it was at least ten feet away from me. Needless to say, I focused on the trail so much on my way out that I didn’t see any more birds.

Jumping Viper at the Monteverde serpentarium.

Western Hognose Viper at the Monteverde Serpentarium.

I don’t have any personal encounters with Tropical Rattlesnakes to relate but assume these are pretty easy to avoid because they would be easy to see along roads or the wide trails where most birding in the Pacific Northwest is done (don’t walk into the tall grass!).

Tropical Rattlesnake at the Monteverde Serpentarium.

In addition to watching where one walks, one also has to always be careful of the understory vegetation. In other words, don’t brush up against the leaves and do not grab any stems or tree trunks. Spines, thorns, nasty caterpillars, and sting-happy ants are just waiting to give you a surprise, and Eyelash Vipers won’t ask if you really meant to grab them before biting. The Eyelash Viper could be the most common venomous snake in Costa Rica and is the one most often seen. Rather small, this arboreal pit-viper rarely reaches more than two feet in length. It prefers to sit and wait in bushes, and on the understory vegetation for lizards, frogs, and birds. The beautiful golden phase stands out but the more typical mottled, green phase blends in perfectly with the mossy vegetation. Just don’t get too close to the vegetation though, and you will be alright.

A small Eyelash Viper at Quebrada Gonzalez.

Another at Bijagua.

There are also other rarer, arboreal vipers found at higher elevations but I don’t have any images of those.

Coral Snakes are far from rare in Costa Rica and at least a few species occur here with the two most common being the Central American and Allen’s Coral Snakes. I see a Coral Snake every once in a while in the woods, on a grassy lawn, or even in a coffee plantation. Although highly venomous, since they don’t blend in with their surroundings, you aren’t likely to step on one and are only likely to get bit if you pick one of these cobra relatives up and play with it (an obviously bad idea that herpetologists somehow can’t stop themselves from doing).

Central American Coral Snake at at the Monteverde Serpentarium.

Of course the poisonous snakes are the most exciting but in reality, on the rare occasions when I come across a serpent, it is of one of the many non-venomous species. One of the more frequently seen species is the Oriole Snake. This arboreal species can get quite big- in fact the largest snake I have seen in Costa Rica was a 8-9 foot individual of this species hanging out in the trees next to the HQ at Quebrada Gonzalez.

Oriole Snake in the Monteverde Serpentarium.

And here is a Tiger Rat Snake I saw at Rara Avis.

Some other fairly common snakes that I do not have pictures of are Salmon-bellied Racer, Mussarana, and Vine Snakes. I would like to have more images or at least augment my snake list but it’s just so hard to focus on looking for herps when there are so many birds to look for, watch, and study.

In any case, I hope this post doesn’t scare anyone from visiting Costa Rica. I think no matter where one travels, visitors will be safe as long as they take proper precautions for any potentially dangerous organisms. In Costa Rica, this means staying on the trail, watching where you walk, and it doesn’t hurt to hire a guide.