As I sat by a cave entrance in the Kimberley, Western Australia, ghost bats zoomed out into the night sky, as they turned once in the open, their taut wing membranes made the sound of a stunt kite on a tight line. A quick chirp from each one and they vanished into the night. One stayed close, hanging from a nearby tree, scanning the ground for prey.
Without doubt one of the coolest bats in Australia, the ghost bat (Macroderma gigas) is the largest of our microbats. Most microbats are content feeding on insects caught in the air or snatched from vegetation. Not this bat. Only the largest insects will do, and often they want more. Frogs, lizards, mice, other bats and even birds as large as doves are commonly grabbed to be devoured. Prey is taken to a special feeding spot to be consumed. Piles of bones, feathers and assorted bits of prey animals are a sure sign of a feeding spot.
It took me hundreds of kilometers, many nights of observing and several trials that failed before I got the results I wanted. A tiny cave in the Northern Territory was the answer I had been searching for. A welcome tip-off from a friend was all I needed. Once I found the damn thing it all fell into place.
I approached the cave and could hear chirping coming from inside. Despite being ruthless predators, the ghost bat is extremely social. Clumping together in large numbers is how they spend most days, chattering to each other like budgerigars. I decided to hang back and not enter the cave itself as the bats would be disturbed. So I set up my home-made infrared trigger vertically, aiming the five flashes at the beam where I imagined the bats would hit it. I had forgotten to bring batteries for the camera trigger! The idea was to have the bats trigger the camera into a 1 second exposure, then fire the flashes as soon as they hit the second beam. So I was stuck with using only the flash trigger with 5 flash units and a shutter release cable. With the camera set to Bulb, I only had to sit and wait. Holding the shutter open manually until the flashes fired, then starting again. It worked very well, but it was a pain being stuck there with the camera.
First came the leaf nosed bats (Hipposideros ater) in three colour forms; orange, pale and grey. These tiny bats appear very delicate, fluttering around like moths. As I was set up for the much larger ghost bats, these little ones did not take up as much of the frame as I wanted. I just had to wait for the ghost bats and ignore all of the wonderful opportunities for leaf noses. The only images I managed had to be severely cropped…
At about 7:30, well after dark, the ghost bats began to stir. I could hear thunderous wing beats inside the cave and more chirping than before.
Whoosh! The first came rocketing out, chirping as soon as it was in the open. Others from another entrance joined it. The flash had gone off, but the bat was slightly clipped on the image edges. Over the next hour, many more came out and most triggered the flashes. It was a real treat to finally have a proper win with ghost bats. I left them to be and headed home, right after trying to get a last minute shot of some leaf noses which had backed off their activity at the cave entrance.