Seeing a Ghost: Tracking the Black-headed Bushmaster



Seeing A Ghost

Authored by Stephen Spear

It all started with a quick glance at Facebook in early May. In my news feed, there was a photo of a Black-headed Bushmaster, which is not something you see very often. A closer look increased my excitement—the post was from a guide that I know on the Osa in Costa Rica (it was his first sighting in 19 years there), and even better, this snake was at a site where we had previously searched! I immediately contacted my collaborator, Guido Saborío, who hadn’t yet heard the news. The snake stayed in the area for the next week, and became an Osa sensation, at least among those with an affection for snakes. For many people, even lifelong Osa residents, this was the first time they had ever seen a wild bushmaster.

Seeing A Ghost

Multiple friends asked if I was going to head down there immediately to see the snake. And as much as I wanted to, I didn’t see a justification for the trip. The location and habitat where the bushmaster was found was great information for us, and the fact that this individual was found very close to where a bushmaster was seen several years ago suggests that perhaps bushmasters regularly return to the same areas. Of course, we really wanted to have more information on where bushmasters go and what they do, but because we couldn’t predict when a bushmaster was going to show up, we didn’t have anyone available that could at a moment’s notice be able to track this animal. Or so I thought.

Seeing A Ghost

Guido was able to see the snake a few days after it was discovered, and the next morning while at breakfast with friends, I got an e-mail from him. He wanted to talk right away. I called back, and Guido said he thought we should really try to track this snake—after all, when were we going to see another one? I told him I agreed but that I didn’t see how we would be able to track the snake without someone available to help, plus I would need to borrow a transmitter from someone. Guido replied that our friend Marcelo, who had participated in most of our previous bushmaster expeditions, was available and willing to track the snake. With that information, the possibility of finally tracking one of the rarest snakes in the world became real.

Seeing A Ghost

The next few days the plan came together at the same time that I was doing Hellbender surveys in Tennessee and North Carolina (you may recall #SteveTakesOver). That Tuesday, I confirmed that a transmitter purchased for a project by University of Georgia student Katie Bentley was not in use and was available for the bushmaster. I called Guido that night and told him I was all set if the snake was still there. Marcelo headed down to the Osa on Wednesday, and Thursday afternoon I got a message that he had captured the snake. I booked my flight that night, and three days later, I was in Costa Rica.

Typically, radio telemetry of snakes involves surgical implantation of the transmitter inside the snake’s body. Simply put, we were not prepared for a surgery—we barely had enough time to track down a transmitter, antenna and receiver! There were other concerns, as well. I wanted to be very cautious with such a rare snake, and I also did not know how far the radio signal might travel in the jungle and didn’t want to immediately lose an implanted snake if it decided to move far. Our alternative was something that our former technician Kiley Briggs had adapted for some snakes in our Vermont Timber Rattlesnake project. This involved using waterproof medical tape to hold the transmitter onto the side of the snake. This procedure seemed to hold well for the Timber Rattlesnakes, and we expected it should stay on until the snake sheds. It is also much less invasive for the snake.

Of course, we still had to get the snake safely into a restraining tube to put the transmitter on without harm to either us or the snake. The first time I looked at the bushmaster in its temporary holding container, it raised its head up and looked at me, similar to what a cobra might do. I took a deep breath. This was going to be very different than any snake from the United States! For the next few minutes, Guido, Marcelo and I discussed strategy and a plan for tubing the snake. Luckily we had a ProBagger system, which would make the tubing process much safer, as we could get in the snake in a large bag and then get it to go up a tube without putting ourselves within strike range.

After what felt like an eternity, but was probably only a couple of minutes, we managed to get the snake in the bag without it thrashing around or trying to strike. It was never aggressive, just very wary. A few minutes later the bushmaster headed up the tube, and we were ready to attach the transmitter. Feeling the bushmaster’s scales was simply amazing. They are so thick it feels like armor. With all due respect to other reptiles, this is what I imagine a dragon would feel like. The snake was very calm while we taped on the transmitter and as we measured and weighed it. The snake measured over 6 feet, 7 inches (2.02 meters) and weighted nearly 6 pounds (2.7 kilograms)!

As we released the snake back at its capture location, I was impressed by how calmly the snake exited the container and went into the forest. It did not rapidly flee, but at the same time it kept its distance from us as it moved away. After some photography in the natural environment, we headed back to the lodge. Returning just before dark to check on the snake, we found it had moved about 30 feet or so to the base of a large tree, where it was in a tight coil underneath a hanging dead palm leaf that no doubt served as a nice rain fly. For the rest of my week on the Osa, the snake stayed in this location, although the changes in its coil made it clear that it was moving around some in that spot. We are currently planning to use night vision goggles and infrared cameras to observe some of the snake’s nocturnal behavior.

Since I left the Osa a couple weeks ago, Marcelo and the landowner Eduardo have been continuing to successful keep tabs on this magnificent animal. So far, it has stayed in the same general area, coiling in a different spot every few days. We are excited to continue to get an inside glimpse at this elusive snake and are discussing possibilities of tracking the snake for a longer period of time. We are also excited about the potential to observe and perhaps track other bushmasters that might interact with this individual. Combined with plans to test a protocol for dog detection of bushmasters in the fall, it is an exciting time for our bushmaster conservation program!