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Tennis Balls and Bats

Brad Law

I don’t mind a game of tennis, especially at night when the inky darkness beyond the floodlights hides all sorts of creatures great and small (owls, frogmouths, flying-foxes and possums to name a few). Not long ago, I was closely watching the ball loop back over the net when a small dark bat silently zeroed in. In fact, it was not much bigger than the tennis ball, so it wasn’t intent on a feed, rather I suspect it was just curious about this (relatively) large object moving through its space.

The bat was likely an Eastern Bent-wing Bat, which I have previously found nearby roosting during the day in large storm water drains. The bats are active through the warmer months in Sydney feeding on small flying insects, especially moths. As the climate warms in our cities these bats are becoming more active through winter months, probably in part because of the urban heat island effect.

In New South Wales, two species of bent-wing bats are listed as threatened although you can sometimes be lucky and see them silhouetted at dusk or maybe during a game of night tennis when they hunt insects drawn to the lights.

Bat detectors pick up their ultrasonic echolocation calls (inaudible to humans) and so they offer a great way to study microbats. The attached recording was made from a Gould’s Wattled Bat in flight in Sydney. I like this particular sequence of calls because it contains the standard echolocation calls, but also a social call and a feeding buzz (towards the end).

So much still to learn about our bats!