Tadarida australis
If you live in Australia anywhere south of the tropics, you’re more familiar with the White-striped Mastiff Bat than you realise. Chances are you’ve heard its call every summer night when you’ve gone outside or when you’ve opened the windows to let in a cool breeze. And it’s just as likely that you had no idea that you were hearing it at all.
Most likely, you thought the sound you heard was insects clicking. You might also have mistaken it for the sound of electricity tapping in powerlines: more than once I’ve stood late at night at Victoria Park station in Collingwood and heard the whickering of the lines overhead signalling a train approaching from the next station and the sound is not dissimilar, if a little louder than the bat’s call.
It’s a difficult sound to describe, the call of the White-striped Mastiff Bat. It’s a clicking, mostly, a kind of a tapping click – but there’s a little bit of squeak in there as well, just a touch of high-pitched pipping as an undertone. It’s not a “call” as such, at least not as that term would be used to describe the sounds made by birds or by other mammals: it’s not an alarm or an announcement. What it is, of course, is the sound of the bat’s echo-location, and if while listening to a White-striped Mastiff Bat you hear a sudden pattern of clicks in rapid succession that’s the sound of the bat homing in on an insect – and if there’s a big kind of fat click at the end of it all, that means the insect’s been caught.
The White-striped Mastiff Bat’s call is a small noise, though, so maybe it’s not as noticeable as I think it is. Certainly I don’t think I’d ever really paid it much attention until one of my lecturers pointed it out to me on a field trip back when I was in university in the early 2000s. There’s a lot of noise in the world, increasingly so, and I guess the night-time clicking of a small bat doesn’t immediately demand our attention. There’s all the difference in the world between hearing and listening, and to notice the call of the White-striped Mastiff Bat I think you have to actually be interested in paying attention to it; you have to be prepared to listen to the world. I’m not sure that so many people are, these days, and I think that’s a shame.
If there’s one device that’s done more than any other to close our ears to the sounds of the world around us, it’s the iPod. Even at its most popular, the Walkman of my youth never reached anything approaching the near-universal use the iPod enjoys. I do own an iPod so I shouldn’t rail against them too much, but mine almost never leaves my house and in general they’ve always struck me as profoundly antisocial devices.
Perhaps I shouldn’t be so hard on them, though, or on the people who use them. Hearing is unique among our sense in that we can’t turn it off. We can’t close our ears and we can’t choose not to hear. So perhaps that’s why people so love their iPods, or whatever MP3 player they favour: if you can’t turn your ears off you can at least fill them with sounds of your own choosing. Personally, I prefer to listen to the world – but then, maybe that’s not so dissimilar; I suppose by focussing so intently on the external I’m granting myself a few moments of respite from the ceaseless torrent of thought inside my head. Just as surely as we’ve all wanted a little silence every now and then, so we’ve all wanted at one time or another to escape from our own heads; and just like hearing, thought is inescapable and unstoppable. Look at me here, doing far too much of it and writing it all down.
So I guess now more than ever the White-striped Mastiff Bat, never the most conspicuous of animals, is becoming just another of the planet’s unseen creatures. There’s a bird on the east coast of Australia called the Eastern Bristlebird (Dasyornis brachypterus), and it’s regarded as one of Australia’s rarest birds. It’s found in very few places, which is always guaranteed to put any species at risk. Yet, the one time I’ve seen it – again, on a university field trip, to Jervis Bay – it was neither rare nor shy. My classmates, lecturers and I went to the carpark at the edge of the National Park at dawn and the ground was thick with bristlebirds; but because their natural habitat is coastal scrub so extraordinarily dense that nothing much larger than a bristlebird can penetrate it, the only reason we were seeing the birds at all was because in those few brief hours around dawn they were allowing themselves to be seen: scurrying out of the bush to forage on the bare gravel of the carpark and the walking tracks radiating from it, before retreating again as the day got hotter. It was impossible to guess how many or how few of them might have been out in that scrub.
You might catch sight of a White-striped Mastiff Bat at dusk, as it emerges from its roost and flies high around the crowns of trees hunting insects. It’s small, but large by microbat (Microchiroptera) standards, and you can differentiate it from small birds or large moths by the power and speed and yet astonishing agility of its flight. Most likely, though, you won’t see it: it flies high, high enough to forage above other species of microbats and high enough, incidentally, to be out of human sight once night falls. In its own way it’s invisible and you might never know it was there – but for its call. By happy accident it’s one of the few microbats whose call can be heard by human ears, and on a warm night there’s nothing I find quite so strangely comforting as hearing it as it flies unseen above us, and knowing with certainty that there’s a whole other world up there, thriving and indifferent to our curiosity, completely external to us, and just out of sight.
Image sourced from http://www.abc.net.au/
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