Grotte du Puits des Terres Basses

Yesterday we (Madam J, Yann, Marie, Robin and myself) undertook a rather exciting expedition. Our first mission was to find La Grotte du Puits des Terres Basses, the largest known bat cave on the island. I had previously searched for it a bit, but had not found it, but we were determined.

First we drove to the general location in the lowland area of the French side of the island and consulted our map. Using coordinates I obtained from a scientific paper, we plotted the point as best we could. I counted paces between the two nearest landmarks, an intersection and the beginning of the nearest salt pond (750 paces) while the team determined the relative distance between the two. Once we located the best starting point from the road, we headed into the forest in search of the cave.

Yann, Marie and I were exploring the hillside when I heard a cry from Yann a hundred feet away. He had found the cave. Although the opening to the cave was quite large, it was difficult to see for more than a short distance due to the contours of the hill and the dense vegetation. In fact, Yann had actually heard the bats before he saw the cave.

The cave itself was as described in the scientific paper, an opening about seven meters wide at the base of a fifteen meter tall limestone outcrop, with visible evidence of past mining. There were two main chambers, and the air was ringing with squeaking bat noises. The stench was bearable, but unpleasant.

Inside the cave there were hundreds of bats. In the left chamber there were large groups near the tallest point of the ceiling in groups several feet wide of solid bat. In the many circular recesses in the ceiling, presumably from mining activity, there were clusters of dozens of bats. Others clung to the ceiling alone or in small groups and there were quite a few flying about the cave. The entire floor was covered in some sort of seeds. I would guess they were the pits of some type of fruit that the bats ate.

The right chamber had a smaller entrance and a couple large holes at the far end of the ceiling that let in light. Some long vines dropped from the holes to the bottom of the cave, and there was a large bird’s nest in a recess near the ceiling. The ceiling in that chamber was also full of bats. On the floor, there were large patches full of cockroaches, very Indiana Jones-style.

As we explored and took photos we noticed the bats reacting to our camera flash. The high-pitched buzz of the bats would turn into an even higher-pitched squeal just after the flash went off. It was surprising and a bit unnerving to hear hundreds of bats complaining about the flash. We were a bit worried about temporarily blinding them with the light, but then remembered that they use echolocation and weren’t as worried.

The air was thick with mosquitos and some members of the team had seen enough, so after taking some more photos we headed back down towards the car, exhilarated at our success and ready to continue on the next part of the day’s mission, but also already contemplating our next visit to this wondrous cave.

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