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Blissfully batty over bat calls

Published 17 Apr 2020 by Eliza Herbert

Bats have been getting a bad rap lately, but we think the critters are pretty amazing. The little (mostly) nocturnal mammals play a big role in biodiversity and can help us to understand more about the country.  

With over 1000 species, they are one of the largest groups of mammals in the world and make up nearly a quarter of the world’s mammal species.

Hundreds of plant species rely on bat-pollination for survival, and what’s more, bats disperse the seeds of trees and other plants as they fly through the night sky; digesting fruit and then excreting (yes, excreting) the seeds far and wide in their own ready-made fertiliser (take that deforestation).

They’re even pest controllers, eating lots and lots of insects and preventing their overabundance in what’s called biocontrol for invertebrates. Or, in human terms, keeping all the bugs off you as you sit in your backyard at night (cue our treasured superhero: batman).

So, when opportunity came ‘calling’ at our Boolcoomatta Reserve’s door to better understand arid-zone bats in South Australia, our South East team jumped at the chance.

Off the bat of the Government’s Murray Darling Microbat Project, our Arid Rangeland ecologist Dr Graeme Finlayson was offered the chance to set up a number of Anabat detectors to help us understand more about which species live in the area, their distribution and behaviours.

An Anabat detector is electronic equipment that helps with passive monitoring of bats by detecting and recording their ultrasonic echolocation calls.

Echolocation calls of bats are unique to each species and can be a handy way to identify what bats are in what areas.

Many of their frequencies can’t be detected by the human ear, so to determine which bat-call belongs to what bat species requires comprehensive reference collections.

Here’s where we throw in a few strange facts that differentiate bats:

  • Some bats have really big ears
  • Others are able to temporarily switch their ear muscles on and off so that they are not damaged by the loud pulse of their echolocation calls as they fly (The Tadarida can even switch its ear muscles on and off 50 times a second in perfect synchronicity!)
  • And some little microbats can only be differentiated by the morphology of their penis, how’s that for an identification process?
The good news at Boolcoomatta was that despite the dry conditions and generally low insect numbers, there were over 10,000 bat calls.

While local reference collections pose a challenge to identification, the team identified eleven different bat species. Some like Gould’s Wattled Bat, the White-Striped Free-tailed Bat and the Inland Forest Bat had previously been recorded at Boolcoomatta. But excitingly, hundreds of recordings revealed bat species that had not previously been recorded in the area, like the Yellow-bellied Sheathtail Bat, the Inland Broad-nosed Bat and Little Broad-nosed Bat.

The next step is to set up Harp traps to capture and confirm in the flesh some of the species that they weren’t entirely confident about and to build up a reference collection to assist with future monitoring using bat call detectors.

But for now, it’s safe to say, we’re still blissfully batty about bats here at Bush Heritage.

Lesser Long-eared Bat. Lesser Long-eared Bat.
Gould's Wattled Bat. Photo by Matt Clancy Gould's Wattled Bat. Photo by Matt Clancy
Graeme out collecting the bat recordings. Graeme out collecting the bat recordings.
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