Phnom Sampeou towers over the flat countryside about 12km southwest of Battambang. The name means ‘Ship Mountain’ because the shape of the hill looks a bit like a ship. Although this mountain has a Buddhist temple built on it, it’s recent history is dark. Thousands of people were executed by the Khmer Rouge here. Many were thrown through the roof of one of the caves, now known as the Killing Cave, and left to die in the cold and dark.
We didn’t have time to see the Killing Cave as we were delayed at the bamboo train (see my last post) and didn’t get to the mountain till dusk. However, we were just in time to see the emergence of countless Asian wrinkle-lipped bats (Chaeraphon plicatus) from a cave high up on the north side of the cliff face. We watched as thousands, maybe even millions, of bats poured out of the mouth of the cave. It was a mesmerising exhibition; you can watch a short video of it here.
The sky around the cave was black as they flew out and took their place in a long column of bats streaming across the countryside. After a while our driver took us back to the main road so we could watch them making formations in the sky, similar to starling murmurations.
Starling murmurations are also aerial displays that can be seen at dusk. Murmurations can be made up of a few hundred to tens of thousands of birds who flock together and seem to move as one. It has recently been discovered that starlings in murmurations co-ordinate their movements with the seven starlings nearest them to create the synchronized movements. When one bird changes speed or direction, all the other birds in the vicinity do the same almost simultaneously. In this way, information spreads across the flock rapidly in an amazing example of collective behavior.
The spectacle at the bat cave lasted over 40 minutes so you can imagine how many bats there were. Our tuk tuk driver told us that they fly to Siem Reap each night eating insects along the way and return to their roost in Phnom Sampeou at dawn. Apparently, you can see the display in reverse at dawn … if you’re up at that hour!