As the sun disappeared below the horizon we turned our eyes back to the hills, watching and waiting. And then we started to see the bats of Mulu take flight.
It was quite a surreal experience. The sound we were hearing was a cacophony of insects in the rainforest and jungle that surrounded us. As the skies got darker we could make out these dancing black clouds as the bats of mulu streamed out from the caves, ready to wreak devastation upon those noisy insects. But not so much devastation as to lessen the noise in any way.
Today's photo is a tad grainy. ISO 100 slide film, hand held, aperture was likely f/2.8 or f/3.5, shutter speed too slow for a sharp shot. The white clouds helped the exposure a bit. This view is to the south, that's why the sky gets darker to the left of the image. The hills are perfect black silhouettes.
Rising above the hills are literally millions of the bats of mulu. They seemed to form columns, a though they they left their caves in an orderly fashion, the column width being the width of the mouth of the cave. Sometimes in the UK and US I've seen flocks of birds put on impressive displays of synchronized flying. These bats were equally impressive, only more so.
I recall our guide telling us they would fly as far north as the coast and then return each night – a round trip of over 100 miles!
We stayed until the last vestiges of light had left the sky (which didn't take long since mulu is about 4 degrees north of the equator). As long as there was some light we could still see bats streaming overhead.
I'm left wondering how the bats that roosted in the deepest reaches of the caves, where there was no light even during the day, knew when night had fallen. Was it the movement of bats closer to the cave entrances, was it changes in temperature as the sun wend down, did they just feel hungry? I don't know.
