Following Bushmasters on the Osa Peninsula



Authored by Marcelo Carvajal

Two months ago, I wrote about the opportunity that we had to track and follow a Black-headed Bushmaster. This project is still ongoing, and this month, research technician Marcelo Carvajal gives his perspective on what it is like to follow this snake on a daily basis. Along with La Tarde owner Eduardo Castro, Marcelo is responsible for tracking and collecting data on the behavior and habitat of the bushmaster. I have known Marcelo for two and a half years, and since that time he has contributed regularly to our survey efforts in Costa Rica. He has great knowledge of the natural history of the forest and has taught me a lot, as well. We are very lucky to have him working on the current radio telemetry project, and I think his enthusiasm for bushmasters and rainforest conservation is clear in this article.

—Stephen Spear

Finding Bushmasters

In the beginning of May, a neighbor of La Tarde on the Osa Peninsula in Costa Rica was walking through the mountains with a friend when he happened to come upon a Black-headed Bushmaster coiled in the buttress of a tree. He knew that if he told his friend what he had seen, he would most likely kill the animal, so he kept it to himself. The next day he went to Eduardo Castro, the owner of the property, where he had found the snake and told the owner what he had seen. Luckily, Eduardo had already participated in the bushmaster project before, so he knew the importance of the snake and the opportunity that this meant.

Eduardo and a couple of friends headed down to the place where the snake was supposed to be, only to find an empty buttress. They searched and searched, and as hours went by, they decided that it was long gone. However, to their surprise one of the people with them almost walked into it. That’s when everything really started to come together.

Finding Bushmasters

I received a message from Dr. Stephen Spear asking if I had seen the pictures on Facebook about a bushmaster on the Osa. I immediately started looking for the said pictures and found that, indeed, they were seeing this rare, elusive beast in a place where we had already been searching for it. After a couple of phone calls, everything was set. I was on my way to Golfito to meet up with Guido, and the very next day we were off to the mountains in search of the snake.

Once we got there we could barely believe that we were awake and that we were about to see the animal that we had been searching for all these years. Countless days and nights, and the most grueling hikes in areas of Corcovado National Park that a lucky few get to know. We searched through rain storms, mud and the steepest hills on the peninsula with no luck. And now, we were about to make this dream come true. Hiking with Eduardo is at best tough—hiking the jungles of the South Pacific of Costa Rica for all his life has made him a really fast, walking GPS. When he slows down, it’s because there is something there.

Finding Bushmasters

So when Eduardo finally slowed down, I knew that we were close… but when he stopped and pointed out the snake, I couldn’t see it. It took me a bit to pick it out from the leaf litter. After the laughs, high fives and pictures, we didn’t want to leave. However, we did. Back in Golfito we started going a little crazy and brainstorming a way to get something going. All these years, a snake finally appears, and we just take pictures? “No! Let’s do this!” was our answer—we wanted to seize the opportunity.

A few days later I was back in the mountains of Corcovado with Eduardo looking for the snake. It took us a good three hours until I finally spotted it. Then we had a tough decision to make: capture it, or wait and risk losing the snake again. It took me about three seconds to think that one out. The next thing I know, we have the snake secured and are carrying it back to the house. A few days later the snake had the transmitter on it, and we were carrying it back into the mountains where we caught it.

Then the interesting part began: following the snake around the forest every day. Using telemetry we set off to track down this living land mine while trying not to step on it. And as you can imagine, navigating through such thick jungle with an antenna can get to be a bit tricky. All this meant more mud, more rain storms, ticks, mosquitoes and more horse flies than I could’ve asked for. However, it’s all part of the experience. How could it be a tropical jungle without feeding all the parasites around?

Some days the snake moved quite a bit, and being so secretive and so perfectly camouflaged, it took us almost an hour to find it. As time went by we started understanding the snake, what it likes, the things seen in the forest that indicate a bushmaster has been around, sometimes forgetting about the other snakes that inhabit the forest floor. However, there is a healthy population of Terciopelo Vipers (Bothrops asper) out there that constantly remind us of them. All of this snake tracking has made us walk well off the beaten path, sometimes having to share the trails that tapirs, brocket deer and peccaries make, and sometimes coming upon puma, ocelot and jaguarundi tracks.

A month went by in the blink of an eye, and then something happened that I thought wouldn’t happen so fast—a second snake appeared. Exactly one month after we placed the transmitter on the first snake, the phone rang at 9:00 p.m. A local taxi driver came upon another bushmaster and called us to see what we could do. We jumped on the motorcycle and drove to where the alleged bushmaster was. Arriving to the spot I asked where it was, and the guy pointed to the ditch. I walked over, and to my surprise, it really was a bushmaster. We caught and safely transported the snake back to the house and then started calling everyone to give them the good news.

At first the idea of a second snake in just two months was too much for all of us. What are the chances? With a transmitter in place, we freed the second snake and started following it through the jungle. Twice the work, twice the awesomeness. We named the second snake “the little guy” just because he is 24 centimeters smaller than the other one, making him 1.76 meters in length.

As time went by we started to notice that most of the things that were thought about this elusive animal are false. Locals say that they are highly aggressive and out to get you, which happens to not be the case. When approached, they do lift their heads and pay close attention to movement, following the person around with that stare that only the bushmaster has. But it won’t attack just because. The only thing they want, like any other animal, is to prevent a violent confrontation. It’s a waste of energy that they can’t afford, and it could mean their very life. Thus, they will flee from danger if they can. If they can’t, obviously they will stand their ground and act menacing in hopes of making the attacker turn around and leave. As a last resort, they will turn to biting.

It has been three months already, and we haven’t been struck at once. And three months in which poaching has almost stopped completely, thanks to these snakes and the project. Not only are we creating a sanctuary for these incredible animals, but every being in the forest is directly benefiting from our work, thanks to the efforts of some visionary minds who decided to change the way of life they were brought up in to start protecting life.

It is such a humbling experience to be in front of such a powerful animal, it’s very hard to describe. We hope that all the efforts put into this will not only take us to the best understanding possible about the biology of bushmasters, but we also hope that through conservation and education, people will stop killing these magnificent snakes.