On Sunday, Neil and I returned to Miami from an epic trip to Puerto Rica. Neil and one of his field assistants flew to the island five days before me to conduct some anole experiments for his dissertation. His assistant had to leave last Wednesday, so I flew into San Juan from Miami to help him with some work and to have an adventure.
I love lizard research as much as the next herpetologist, but I’d be lying if I said that my decision to take this trip wasn’t influenced by ulterior motives. A few biologists had previously told Neil that the Interamerican University in Bayamon ran a field station on the northwest side of the island called Mata de Platano. Near this field station was a special cave called La Cueva de Los Culebrones (the Cave of the Long Snakes). As the stories go, this cave was home to a healthy bat population – around 300,000 individuals. Starting at dusk, these bats were said to emerge from the cave in extraordinary numbers and at the mouth of the cave, Puerto Rican Tree Boas (Epicrates inornatus) would regularly wait, dangling off the of the cave walls to capturing bats in midair. If the stories were true, we had to see this cave and we had to capture the bats and boas on film.
Neil picked me up from the airport before we drove to the Interamerican University to pick up the keys to the field station. We arrived at Mata de Platano field station just before dark, quickly organized our camera gear, and hiked to the Cueva de los Culebrones. When we arrived at the cave entrance, bats were already beginning to emerge for their nightly activity. Sure enough, two boas were tucked into cracks in the cave walls waiting for the right time to begin hunting.
A Puerto Rican Tree Boa (Epicrates inornatus) lays across a vine at the entrance of the cave, La Cueva de Los Culebrones.
As the dusk light faded into night, bats began to pour out like a river of furry wings. It’s hard to describe the sensation of so many bats flying past you. You could feel the air from their flapping wings over your entire body. When we turned on our headlamps the snakes had emerged from the cracks. The vast majority of their bodies dangled off the rock walls and secured by an unbelievably small portion of their prehensile tails. When a bat flapped its wings too close, the snake would strike. Photographing and filming this amazing scene was tough. There was no light and every time we turned on light that were bright enough to film, the bats would disappear back into the cave. After a few hours we called it a night, agreeing to think hard about how to successfully capture this spectacle on film.
Three tree boas hang from the cave wall, awaiting a flying meal. The first snake on the far left strikes unsuccessfully at a passing bat.
The next morning we decided to explore the cave. Cueva de Los Culebrones is about 600 meters long with several enormous atriums, some reaching heights of over 50m. The descent into the cave was tricky – hot, moist bat guano caked the steep entrance. Wearing gloves to keep the bat shit off our hands, we made it into the first atrium. Once we could no longer see the daylight, the guano got deeper and wetter. Festering around the ground were thousands of cockroaches. Perched on the walls were enormous tailless whipscorpions. A dense population of some of the largest cane toads we’d ever seen hopped around the ground, presumably feeding on the cockroaches. Above us, thousands of bats, unhappy about our lights, flew around in a flurry, vocalizing, eco-locating and pooping on us. The heat and humidity in the cave were crazy. We were sweating bullets, but couldn’t wipe it off because our gloved hands were covered in guano. There’s really no other way to describe that place except for dark, disgusting and biologically amazing. I think that both of us were happy to come back out into the daylight, hike back to the field station, and take a long shower.
With slippery bat guano below his feet, Neil carefully descends into La Cueva de los Culebrones.
That evening we returned to the cave determined to capture everything on camera. Unbelievably, this evening was even more amazing than the last. We were at the cave from 4pm to 11pm. At one point, there were nine boas hanging on the walls or off of vines. We saw five kills, and managed to capture one on video. It was a remarkable experience. We plan to put together a video and photo gallery of this adventure on the Day’s Edge website sometime soon, but until then, I’ll just warn you that our footage is incredible.
The next day, we drove back to the Botanical Gardens in San Juan to collect some lizards for Neil’s experiments. We spent Saturday morning hiking around El Yunque National Forest (one of the only tropical rainforests that is part of the United States) before driving to Fajardo to collect more lizards for Neil’s research. Neil had been to Fajardo twice on this trip before I got to Puerto Rica. Both times, he saw the same Puerto Rican tree boa in the same location. Sure enough, the tree boa was in the same location. We caught he snake to get a closer look, and deservedly, the snake skunked me to high-hell.
Neil hikes up a trail in the tropical rain forests of El Yunque, as clouds pass the palm trees at around 3000 ft.
We worked until late on Saturday night processing the lizards that we caught before falling asleep. At around 4am, some drunk guy woke us up by actually coming into our hotel room. I got up immediately and he ran off. I figured that I must have forgotten to lock the door, so I locked it and fell back asleep. Somehow that same drunk fool managed to unlock the door and say something to me before running off. After that we couldn’t fall asleep. Luckily, our flight out of San Juan was early and we were planning to be up by 4:45 anyways. All I can say is that you should never stay the Coqui Inn Hotel in San Juan. All in all, it was a great trip!
Beach in Isla Verde, San Juan just after sunset.